@article { ISI:000311350000013, title = {Simple one pot synthesis of nano gold-mesoporous silica and its oxidation catalysis}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {92-97}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple one pot synthesis strategy using a non ionic triblock copolymer P123 as reducing as well as templating agent has been employed to prepare nano gold particles incorporated in the pores of mesoporous silica catalyst. The catalyst is characterized by XRD, nitrogen adsorption desorption isotherms at 77 K and TEM. The presence of small gold nanopartilces (similar to 2-4 nm) clearly demonstrated that this strategy can be effective in incorporating Au inside mesochannels. The catalyst reduced at 300 degrees C in H-2 was found to be active for oxidation reactions, such as CO oxidation, and benzyl alcohol. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {Alcohol oxidation, CO oxidation, Gold catalysis, Mesoporous silica}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.05.053}, author = {Sekhar, A. C. Sunil and Sivaranjani, Kumarsrinivasan and Gopinath, Chinnakonda S. and Vinod, C. P.} } @article { ISI:000315707600041, title = {Design and performance aspects of a custom-built ambient pressure photoelectron spectrometer toward bridging the pressure gap: oxidation of Cu, Ag, and Au surfaces at 1 mbar O-2 pressure}, journal = {Journal of Physical Chemistry C}, volume = {117}, number = {9}, year = {2013}, month = {MAR}, pages = {4717-4726}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The critical features of a custom-built laboratory version ambient pressure photoelectron spectrometer (Lab-APPES) are presented. A double front cone differential pumping arrangement and an aperture free design employed in the electrostatic lens regime improve the data collection and data quality. In contrast to the conventional X-ray photoelectron spectrometers (XPS) operating at ultrahigh vacuum (UHV), it is possible to explore the electronic structure of solid surfaces under working conditions or closer to working conditions with Lab-APPES. Especially surface-dependent phenomena can be explored up to 1 mbar pressure and up to 873 K by conventional heating methods and at least up to 1273 K by a laser heating method. Simultaneous XPS and reaction kinetic measurements on solid surfaces make the Lab-APPES an important tool to measure the dynamic electronic structure changes on material surfaces under reaction conditions. The interaction of O-2 with polycrystalline foils of Cu, Ag, and Au from UHV to 1 mbar and up to 773 K has been studied.

}, issn = {1932-7447}, doi = {10.1021/jp312706s}, author = {Roy, Kanak and Vinod, C. P. and Gopinath, Chinnakonda S.} } @article { ISI:000317596800004, title = {Synthesis and catalytic activity of monodisperse gold-mesoporous silica core-shell nanocatalysts}, journal = {Catalysis Science \& Technology}, volume = {3}, number = {5}, year = {2013}, month = {FEB}, pages = {1190-1193}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Core-shell nanostructures, where gold nanoparticles of sub 10 nm size are successfully encapsulated inside porous silica spheres, have been prepared. The detailed characterization of the catalyst shows a high surface area and good mesoporosity. The sinter resistance of the catalyst under repeated cycles of the CO oxidation reaction is observed.

}, issn = {2044-4753}, doi = {10.1039/c3cy20772b}, author = {Sekhar, A. C. Sunil and Meera, C. J. and Kottavarithottil Ziyad and Gopinath, Chinnakonda S. and Vinod, C. P.} } @article { ISI:000337786700050, title = {Structure sensitive chemical reactivity by palladium concave nanocubes and nanoflowers synthesised by a seed mediated procedure in aqueous medium}, journal = {Nanoscale}, volume = {6}, number = {13}, year = {2014}, month = {JUN}, pages = {7496-7502}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Palladium nanocubes and their transformation to concave nanocubes and nanoflowers are realised by a seed mediated procedure in aqueous medium and at room temperature using cationic surfactants. The concave nanocubes and nanoflowers were found to be enclosed by high index facets. The under coordinated atoms present on the high index facets make these nanostructures chemically more active towards Suzuki coupling and Heck coupling reactions compared to the conventional nanocubes and spherical nanoparticles of similar size.

}, issn = {2040-3364}, doi = {10.1039/c4nr01283f}, author = {Sreedhal, S. and Sudheeshkumar, V. and Vinod, C. P.} } @article { ISI:000353249500020, title = {Demonstration of synergistic catalysis in Au@Ni bimetallic core-shell nanostructures}, journal = {Journal of Physical Chemistry C}, volume = {119}, number = {15}, year = {2015}, month = {APR}, pages = {8138-8146}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Coreshell bimetallic nanoparticles comprised of gold core and varying nickel shell have been synthesized, and their synergistic effect in catalysis is explored through catalytic hydrogenation of p-nitrophenol and p-nitrothiophenol. A clear evidence for synergism in Au@Ni core-shell nanoparticles having an ultrathin Ni shell (1-2 nm) around a Au core (6-10 nm) resulting in enhanced catalytic activity is observed. The rates observed from a thin nickel shell are higher than monometallic Au or Ni nanoparticles of similar size or with a thicker Ni shell of 6-8 nm.

}, issn = {1932-7447}, doi = {10.1021/jp5128089}, author = {Vysakh, A. B. and Babu, Chinchu Lizen and Vinod, C. P.} } @article { ISI:000349088000020, title = {Oxidation catalysis by large trisoctahedral gold nanoparticles: Mind the step!}, journal = {Catalysis Today}, volume = {244}, year = {2015}, month = {APR}, pages = {177-183}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

To understand the origin of catalysis by gold and to probe the role of defects and interfaces, benchmark reactions namely CO oxidation and benzyl alcohol oxidation were carried out on supported trisoctahedral gold nanoparticles and on the inverse catalyst system. The sizes of these particles which are between 45 nm and 110 nm, are well beyond the quantum size regime and well above the optimum size range where gold is considered to be catalytically active. The periodic steps sites in contact with oxide support interface were able to promote the reaction. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {CO oxidation, Defects, Gold catalysis, Inverse catalysta, Steps and kinks}, issn = {0920-5861}, doi = {10.1016/j.cattod.2014.02.049}, author = {Sreedhala, S. and Sudheeshkumar, V. and Vinod, C. P.} } @article { ISI:000364032500052, title = {Preparation of mesoporous titanosilicate with isolated Ti active centers for cyclohexene oxidation}, journal = {RSC Advances}, volume = {5}, number = {112}, year = {2015}, month = {OCT}, pages = {92371-92377}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We report the preparation of mesoporous titanosilicate with active Ti centres using CTAB as the structure directing agent and ethylenediamine as the complexing agent (TSC-ED). The finalmaterial contained isolated Ti4+ centres substituting Si4+ in the mesoporous silica framework. The crucial role played by ethylenediamine in complexing with Ti4+ during the sol-gel process and preventing the phase segregation of TiO2 was studied systematically. The textural parameters, structural order, morphology, nature and co-ordination of Ti species were analyzed using various techniques such as X-ray diffraction (XRD), UV-vis diffused reflectance spectroscopy (UV-vis DRS), UV resonance Raman spectroscopy, Fourier transformed Infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transition electron microscopy (TEM), and X-ray photoelectron spectroscopy. Finally, the catalysts were tested for catalytic activity in the oxidation of cyclohexene using various oxidants.

}, issn = {2046-2069}, doi = {10.1039/c5ra18044a}, author = {Gupta, S. and Vinod, C. P. and Jagadeesan, Dinesh} } @article { ISI:000356021300023, title = {Surfactant assisted formation of ruthenium nanochains under mild conditions and their catalytic CO oxidation activity}, journal = {Chemical Communications}, volume = {51}, number = {50}, year = {2015}, month = {MAY}, pages = {10178-10181}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Spontaneous formation of ruthenium nanochains is accomplished in aqueous medium under mild conditions using a seed mediated protocol with cetyl trimethylammonium bromide (CTAB) as the capping agent. They are formed due to the random self-assembly of Ru seeds of similar to 3.5 nm size. These 1D nanostructures exhibit better catalytic activity towards the oxidation of CO relative to the similar to 3.5 nmseeds and 6 nm Ru nanospheres. The synthesis strategy adopted here is found to be simple, facile and environmentally friendly.

}, issn = {1359-7345}, doi = {10.1039/c4cc09430a}, author = {Sreedhala, S. and Vinod, C. P.} } @article { ISI:000374920400016, title = {CO oxidation on large high-index faceted Pd nanostructures}, journal = {Journal of Catalysis}, volume = {337}, year = {2016}, month = {MAY}, pages = {138-144}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

The structure sensitivity of CO oxidation has been investigated on oxide-supported palladium nanoparticles of different morphologies. The reactivity of concave nanocubes and nanoflowers that expose {3 1 0} and {3 1 1} high-index facets showed a lower onset temperature for CO oxidation than Pd nanospheres of size around 6 nm. These concave nanocubes and nanoflowers were also found to catalyze the CO oxidation reaction more efficiently than simple cubes and spheres of similar size that exposed low-index facets. The enhanced activity of these nanoparticles compared with other morphologies are attributed to the presence of sites of under-coordination on the exposed high-index facets. The larger nanoparticles were also found to be more stable in the reaction environment. (C) 2016 Elsevier Inc. All rights reserved.

}, keywords = {CO oxidation, High-index facets, Pd nanoparticles, structure sensitivity}, issn = {0021-9517}, doi = {10.1016/j.jcat.2016.01.017}, author = {Sreedhala, S. and Sudheeshkumar, V. and Vinod, C. P.} } @article { ISI:000373408600014, title = {Correlating the role of hydrophilic/hydrophobic nature of Rh(I) and Ru(II) supported organosilica/silica catalysts in organotransformation reactions}, journal = {Applied Catalysis A-General}, volume = {513}, year = {2016}, month = {MAR}, pages = {138-146}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Highly reactive and hydrophobic triphenyl phosphine based rhodium(I) and ruthenium(II) organometallic complexes over benzene containing periodic mesoporous organosilica (PMOB) have been synthesized. This has been achieved by the immobilization of neat metal complexes like RhCl(PPh3)(3) [Wilkinson catalyst], RuHCl(CO)(PPh3)(3) and RuCl2(PPh3)(3) over aminofunctionalized PMOB to get RhCl(PPh3)(2)-PrNH2PMOB, RuHCl(CO)(PPh3)(2)-PrNH2PMOB and RuCl2(PPh3)(3)-PrNH2PMOB, respectively. The physico-chemical properties of the functionalized catalysts were analyzed by elemental analysis, ICP-OES, XRD, N-2 sorption analyses, FT-IR, solid state C-13 and Si-29 NMR spectra, XPS, SEM, TEM and contact angle measurements. The XRD and N-2 sorption analyses showed excellent textural properties with ordered mesoporous channel structure of all synthesized catalysts. The organic moieties anchored in PMOB were confirmed by C-13 CPMAS NMR and Fr-IR spectroscopy with Si-29 CPMAS NMR spectroscopy providing the information about the degree of functionalization of surface silanol groups with organic moiety. The Rh(I) and Ru(II) complexes supported on MCM-41/SBA-15/PMOE (ethane-PMO) were synthesized, and their catalytic activities in hydrogenation and sulfoxidation reactions were compared with Rh(I) and Ru(II) complexes supported on PMOB. The results show that PMOB based catalysts exhibit higher activities and selectivities than MCM-41/SBA-15/PMOB supported catalysts, neat homogeneous complexes and without catalyst. The better catalytic performance of PMOB based catalyst is attributed to the hydrophobic nature and high surface area of the PMOB support. The recycling studies of anchored catalysts show no major deactivation of the catalyst. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Heterogeneous catalysts, Hydrogenation and sulfoxidation, Hydrophobic, Periodic mesoporous organosilica}, issn = {0926-860X}, doi = {10.1016/j.apcata.2015.12.026}, author = {Lazar, Anish and George, Shoy C. and Jithesh, P. R. and Vinod, C. P. and Singh, A. P.} } @article { ISI:000382349600001, title = {Large trisoctahedral Au nanoparticles encapsulated inside porous silica catalyses CO oxidation at room temperature: probing the effect of encapsulation and the role of step atoms and interfaces}, journal = {Applied Catalysis A-General}, volume = {524}, year = {2016}, month = {AUG}, pages = {1-7}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

As envisaged, a synthesis strategy is reported for encapsulating high index faceted trisoctahedral Au nanoparticles inside porous silica to preserve nanoparticle size by preventing sintering. Further, to probe the role of interfaces an active metal oxide junction was created by decorating trisoctahedral (TOH) Au nanoparticle with nano oxides before silica encapsulation. The activity of these catalysts was tested for CO oxidation reaction. The reaction was found to be facile on these encapsulated large structured Au nanoparticles showing appreciable activity at room temperature compared to non encapsulated counterparts. Apart from preventing sintering, the improved activity is demonstrated due to the retention of morphology and thereby the active centres due to encapsulation. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {Defect sites, Encapsulation, High index facets, Metal-oxide active perimeter, Trisoctahedral Au nanoparticles}, issn = {0926-860X}, doi = {10.1016/j.apcata.2016.05.023}, author = {Sreedhala, S. and Maheshwari, Shruti and Betsy, K. J. and Vinod, C. P.} } @article { ISI:000369533400015, title = {Phenylacetylene hydrogenation on Au@Ni bimetallic core-shell nanoparticles synthesized under mild conditions}, journal = {Catalysis Science \& Technology}, volume = {6}, number = {3}, year = {2016}, month = {JAN}, pages = {708-712}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The synthesis of Au@Ni bimetallic core-shell nanoparticles through an energy efficient (lower temperature) route in oleylamine following a sequential reduction strategy is reported. The method is found to be useful for the synthesis of a very thin nickel shell (2 nm) over a gold core (15 nm). Synergistic effects are observed in catalyzing phenylacetylene hydrogenation under different solvent conditions.

}, issn = {2044-4753}, doi = {10.1039/c5cy02005k}, author = {Vysakh, A. B. and Lazar, Anish and Yadukiran, V. and Singh, A. P. and Vinod, C. P.} } @article {42861, title = {Porous thin films towards bridging the material gap in heterogeneous catalysis}, journal = {Catalysis, Structure \& Reactivity}, volume = {2}, year = {2016}, month = {MAR}, pages = {1-12}, type = {Article}, abstract = {

An attempt has been made to bridge the material gap, existing between ideal single crystals and real-world powder nanocatalyst employed in surface science and heterogeneous catalysis, respectively. Simple wet chemical method (sol{\textendash}gel and spin-coating deposition) has been applied to make continuous Ce1 - xZrxO2 (x = 0{\textendash}1) (CZ) thin films with uniform thickness (~40 nm) and smooth surface characteristics. Uniform thickness and surface smoothness of the films over a large area was supported by a variety of measurements. Molecular beam (MB) studies of O2 adsorption on CZ surfaces reveals the oxygen storage capacity (OSC), and sticking coefficient increases from 400 to 800 K. Porous nature of Ce-rich CZ compositions enhances O2 adsorption and OSC, predominantly due to O-diffusion and redox nature, even at 400 K. A good correlation exists between MB measurements made on CZ films for oxygen adsorption, and OSC, and ambient pressure CO oxidation on powder form of CZ; this demonstrates the large potential to bridge the material gap. CZ was particularly chosen as a model system for the present studies, since it has been well-studied and a correlation between surface science properties made on thin films and catalysis on powder CZ materials could be a litmus test. Ambient catalysis on ceria-zirconia nanocatalyst correlates well with surface properties measured through molecular beam on thinfilm and close the material gap.

}, doi = {10.1080/2055074X.2015.1133269}, author = {Dubey, Anjani and Kolekar, Sadhu K. and Gnanakumar, Edwin S. and Roy, Kanak and Vinod, C. P. and Gopinath, Chinnakonda S.} } @article {45738, title = {Convenient route for Au@Ti-SiO2 nanocatalyst synthesis and its application for room temperature CO oxidation}, journal = {Journal of Physical Chemistry C}, volume = {121}, year = {2017}, month = {MAR }, pages = {4946-4957}, type = {Article}, abstract = {

Small gold nanoparticles.of size less than 5 nm encapsulated inside titanium modified silica shell have been reported. Here, a modified sol-gel method, which is a one-step process, produces Au@Ti-SiO2 nanocatalyst with a good control of titanium loading. With a titanium loading of 0.9 and 2.2 wt \% in silica, unprecedented low temperature activity (full conversion) is observed for this catalyst for CO oxidation reaction compared to Au@SiO2 catalyst. A combination of optimum sized gold nanoparticles with a large amount of oxygen vacancies created due to Ti incorporation in silica matrix is considered to be the reason for this enhanced catalytic activity. The size of.gold nanoparticles is maintained even after high temperature pretreatments, which show the benefit of encapsulation. The effect of the various pretreatments on the catalytic activity has also been reported.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.6b10202}, author = {Soni, Yogita and Kumar, Anumol Erumpukuthical Ashok and Nayak, Chandrani and Deepak, Francis Leonard and Vinod, C. P.} } @article {44167, title = {Diverse reactivity trends of Ni surfaces in Au@Ni core-shell nanoparticles probed by near ambient pressure (NAP) XPS}, journal = {Catalysis Science \& Technology}, volume = {7}, year = {2017}, month = {OCT }, pages = {4489-4498}, type = {Article}, abstract = {A mild temperature sequential reduction method in aqueous medium is reported for the synthesis of Au@Ni nanoparticles with a core-shell morphology. The nickel shell thickness with a gold core in the nanostructure can be tuned from 2 nm up to about 10 nm. Near ambient pressure XPS (NAPXPS) studies under oxygen atmosphere show that Au-80@Ni-20 with an extremely thin nickel shell (similar to 2 nm) follows a distinctly different decomposition pathway of metastable Ni(OOH) species compared to those with larger shell thickness which behave more like individual nickel surfaces. Thus, Ni(OOH) on Au-80@Ni-20 decomposes to metallic Ni at 100 degrees C and is found to resist oxidation at 0.1 mbar oxygen at this temperature. Those with a larger nickel shell thickness behave more like monometallic Ni in terms of their decomposition and oxidation properties. The Au@Ni system with an ultra thin metallic nickel overlayer (2 nm) shows high catalytic activity and selectivity for phenylacetylene hydrogenation under mild conditions which outweighs their monometallic counterparts and those with higher nickel shell thickness.}, issn = {2044-4753}, doi = {10.1039/c7cy01070b}, author = {Bharathan, Vysakh A. and Jain, Ruchi and Gopinath, Chinnakonda S. and Vinod, C. P.} } @article {45731, title = {Exploration of amination reactions on highly extendable active sites of Pd(II)-3-allylsalicylaldiminophenol (ASIP) complex over thiofunctionalized SBA-15}, journal = {Microporous and Mesoporous Materials}, volume = {242}, year = {2017}, month = {APR}, pages = {173-181}, type = {Article}, abstract = {

An effective and impressive heterogeneous catalyst, Pd(II)-3-allylsalicylaldiminophenol-SBA-15, dubbed as Pd(II)ASIP@SBA-15, for amination reactions of aryl halides to synthesize secondary amines (2), has been synthesized and characterized. Pd(II)ASIP@SBA-15 has been synthesized by the covalent anchoring of 3-allylsalicylaldehyde over thiofunctionalized SBA-15, then further reaction with 2-aminophenol, followed by metallation process by using Pd(11)(OAc)(2). A specifically designed cheap and easily available organic ligand, 3-allylsalicylaldiminophenol (ASIP), was synthesized from 3-allylsalicylaldehyde and 2-aminophenol. Using this, the synthesis of Pd(II)ASIP@SBA-15 was carried out whereby the ligand providing an active co-ordination or chelating sites for palladium metal. This strategy helped in exposing the Pd(11)ASIP active sites from surface to channels of SBA-15 support during the reactions. The synthesized catalyst were characterized by CHN analysis, PXRD, Nitrogen sorption analyses, TG \& DTA, FTIR, C-13 and Si-29 CPMASS NMR spectra, XPS, UV-Visible, SEM, EDAX and TEM. Pd(II)ASIP@SBA-15 catalyst was screened in heterogeneous amination reactions of aryl halides to produce N-aryl derivatives or secondary amines with high catalytic activity as revealed by turn over frequency (TOF) calculations. To explore the heterogeneous nature of catalysts, amination reactions were carried with neat Pd(II)ASIP complex and Pd(11)(OAc)(2) catalysts. The catalyst was recycled several times without much loss of activity and Sheldon hot filtration test has been performed. (C) 2017 Elsevier Inc. All rights reserved.

}, keywords = {Amination Reactions, heterogeneous catalysis, Reusable, Supported catalysis}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2017.01.026}, author = {Lazar, Anish and Vinod, C. P. and Singh, A. P.} } @inbook {45781, title = {Model nanoparticles in catalysis}, booktitle = {Metal nanoparticles and clusters: advances in synthesis, properties and applications}, year = {2017}, pages = {165-199}, publisher = { Springer}, organization = { Springer}, edition = {1}, chapter = {Model nanoparticles in catalysis}, abstract = {

The importance of surface structure in catalysis is well documented by a large volume of surface science studies carried out on single crystal surfaces. Recent years has seen rapid strides in the synthesis of structured nanomaterials with varying morphologies and architecture. There is a growing interest in utilizing model nanoparticles like morphology-controlled nanostructures and core{\textendash}shell-like bimetallic nanoparticles in catalysis. Apart from showing unprecedented reactivity, they serve as a model surfaces to answer many fundamental question in catalysis and also to arrive at structure vs activity correlations in heterogeneous catalysis. This chapter gives an introduction to such nanomaterials and recent advances in utilizing these materials for catalytic applications.

}, issn = {978-3-319-68052-1}, doi = {10.1007/978-3-319-68053-8}, author = {Vinod, C. P. and Vysakh, A. B. and Sreedhala, S.} } @article {45419, title = { Enhanced selectivity of 3-D ordered macroporous Pt/Al2O3 catalysts in nitrites removal from water}, journal = {Applied Catalysis A-General}, volume = {564}, year = {2018}, month = {AUG}, pages = {26-32}, type = {Article}, abstract = {Tailored macroporous mesoporous alumina supports have been successfully prepared using a single hard templating approach. Pt nanoparticles, showing similar physico-chemical properties, were homogeneously dispersed throughout the different alumina frameworks as catalytic active phase for drinking water treatment. We demonstrated that careful modification of pore properties of the catalyst (size and connectivity) by pseudomorphic transformation can strongly modulate the reaction rate and selectivity through the limited access to Pt active sites within the alumina porous particles. Specifically, 3-D Ordered Macroporous Pt-Al2O3 catalysts with a high degree of interconnectivity yield to superior catalytic properties (enhanced activity and selectivity) over pure mesoporous counterparts in the hydrogenation of nitrites in water. We found that large pores (240 nm) interconnected with windows (110 nm) alleviate mass transfer limitations and clearly improve NZ selectivity. The findings of this study further suggest the possibility of engineering the pore architecture of the support to fine tune the selectivity for a particular reaction rather than investigating more on tuning the properties of the costly active metallic phase.}, doi = {10.1016/j.apcata.2018.07.014}, author = {Sekhar, A. C. Sunil and Zaki, A. and Troncea, S. and Casale, S. and Vinod, C. P. and Dacquin, J. P. and Granger, P.} } @article {44496, title = {Highly selective aqueous phase hydrogenation of phenols over nanostructured RuO2 on MCM-41 catalysts}, journal = {Nano-Structures \& Nano-Objects }, volume = {13}, year = {2018}, month = {FEB}, pages = {36-43}, abstract = {Selective aqueous phase hydrogenation of phenol as well as its derivatives is important for the synthesis of chemical intermediates which are crucial for the manufacture of high-tonnage commodities and a multitude of value added platform chemicals. Herein, we report a facile catalyst made of highly dispersed small RuO2 nanoparticles supported on mesoporous MCM-41 using one-pot approach. The optimal 5RuO2-MCM-41 catalyst with particle size 6-8 nm showed excellent activity and selectivity in aqueous phase hydrogenation of phenol and other functionalized substrates, which are building blocks of lignin, to corresponding cyclohexanol products without any additives. These catalysts showed better stability and can be reused several times without any significant drop in activity which proves the heterogeneity of the immobilized oxide catalyst.}, doi = {10.1016/j.nanoso.2017.11.004}, author = {Betsy, K. J. and Lazar, Anish and Vinod, C. P.} } @article {44511, title = {Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process}, journal = {Journal of the American Chemical Society}, volume = {140}, year = {2018}, month = {MAR }, pages = {4430-4439}, abstract = {

Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 degrees C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)(4)](-)[Ph3PNPPh3](+) (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol \% acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)(2)(PPh3)(2)] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.

}, issn = {0002-7863}, doi = {10.1021/jacs.8b01286}, author = {Pandey, Swechchha and Raj, K. Vipin and Shinde, Dinesh R. and Vanka, Kumar and Kashyap, Varchaswal and Kurungot, Sreekumar and Vinod, C. P. and Chikkali, Samir H.} } @article {44589, title = {Judicious reduction of supported Ti catalyst enables access to disentangled ultrahigh molecular weight polyethylene}, journal = {Macromolecules}, volume = {51}, year = {2018}, month = {JUN }, pages = {4541-4552}, abstract = {

Heterogeneous Ziegler-Natta and homogeneous metallocene catalysts are known to produce ultrahigh molecular weight polyethylene (UHMWPE) in the entangled state. On the other hand, only (two) homogeneous single-site catalysts are reported to yield disentangled UHMWPE (dis-UHMWPE). This disparity between the two types of catalysts and the two states of polyethylene can be bridged if a heterogeneous single-site catalyst that can yield dis-UHMWPE is made accessible. Here, one-pot two-step synthesis of a MgCl2 supported [Ti(OEt)(4)] derived catalyst 1 with a two-stage activation strategy is reported to produce dis-UHMWPE. Second activation of catalyst 1 was performed by adding excess modified methylaluminoxane (MMAO12), and XPS analysis indicated that the catalyst existed in only Ti(III) state at [A1]/[Ti] ratio of 600. Catalyst 1 after second activation with MMAO12 was found to be highly active in ethylene polymerization and produced dis-UHMWPE. Polymerization conditions were tailored to obtain molecular weight (M-w) as high as 13 million g/mol PE. To the best of our knowledge, this is the first time a heterogeneous catalyst (catalyst 1) that displays pseudosingle site nature is able to produce dis-UHMWPE. The thus-prepared nascent polyethylene revealed a melting temperature of 141-144 degrees C, which is a characteristic melting transition for a dis-UHMVVPE. The disentangled state of the nascent PE and its M-w and MVVD were further authenticated by rheological investigations. Isothermal time, sweep oscillatory experiments in linear viscoelastic limit revealed a rapid rise in elastic modulus followed by equilibration to plateau modulus, which are characteristic features of the disentangled state. Thus, a pseudo-singlesite heterogeneous catalyst has been accessed, which upon second activation with excess MMAO12 led to the production of dis-UHMWPE.

}, issn = {0024-9297}, doi = {10.1021/acs.macromol.8b00590}, author = {Gote, Ravindra P. and Mandal, Dipa and Patel, Ketan and Chaudhuri, Krishnaroop and Vinod, C. P. and Lele, Ashish K. and Chikkali, Samir H.} } @article {45361, title = { One pot ligand exchange method for a highly stable Au-SBA-15 catalyst and its room temperature CO oxidation}, journal = {Chemical Communications}, volume = {54}, year = {2018}, month = {NOV}, pages = {12412-12415}, type = {Article}, abstract = {A modified deposition precipitation (DP) method has been developed to address a fundamental issue of supporting well dispersed Au nanoparticles on silica. Ammonium chloride (NH4Cl) plays an important role in in situ modifying the gold precursor (HAuCl(4)3H(2)O) solution allowing facile deposition of gold NPs in the channels of SBA-15. The Au-SBA-15 catalyst (2.8 wt\%) synthesized by this procedure showed 100\% conversion for CO oxidation at room temperature with excellent stability at room temperature and high temperature.}, issn = {1359-7345}, doi = {10.1039/c8cc06887a}, author = {Soni, Yogita and Kavya, I. and Ajithkumar, T. G. and Vinod, C. P.} } @article {44588, title = {Role of oxygen vacancies and interstitials on structural phase transition, grain growth, and optical properties of Ga doped TiO2}, journal = {Journal of Applied Physics}, volume = {123}, year = {2018}, month = {JUN}, pages = {Article Number: 245702}, abstract = {A systematic study on the effect of gallium (Ga) doping (0 <= x <= 0.10) on the structural phase transition and grain growth of TiO2 is reported here. X-ray diffraction spectroscopy and Raman spectroscopy confirm that Ga doping inhibits the phase transition. Activation energy increases from 125 kJ/mol (x = 0.00) to 300 kJ/mol (x = 0.10) upon Ga incorporation. X-ray photoelectron spectroscopy shows the presence of Ti3+/Ga3+ interstitials, substitution (Ti4+ by Ga3+), and oxygen vacancies in the samples. At lower doping (x <= 0.05), interstitials play a more significant role over substitution and oxygen vacancies, thereby resulting in a considerable lattice expansion. At higher doping (x >= 0.05), the effect of interstitials is compensated by both the effect of substitution and oxygen vacancies, thereby resulting in relatively lesser lattice expansion. Inhibition of the phase transition is the result of this lattice expansion. The crystallite size (anatase) and particle size (rutile) both are reduced due to Ga incorporation. It also modifies optical properties of pure TiO2 by increasing the bandgap (from 3.06 to 3.09 eV) and decreasing the Urbach energy (from 58.59 to 47.25 meV). This happens due to regularization of the lattice by the combined effect of substitution/ interstitials and oxygen vacancies. Published by AIP Publishing.}, doi = {10.1063/1.5027672}, author = {Khatun, Nasima and Tiwari, Saurabh and Vinod, C. P. and Tseng, Chuan-Ming and Liu, Shun Wei and Biring, Sajal and Sen, Somaditya} } @article {44217, title = {Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones}, journal = {Catalysis Communications}, volume = {104}, year = {2018}, month = {JAN}, pages = {62-66}, type = {Article}, abstract = {

Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(Il)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(Il)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L) RuaD@SBA-15 performs high catalytic activity as well as selectivity within 20 min with high TOF. The catalyst can be recycled and reaction parameters are optimized.

}, keywords = {Acetalization reactions, Acid free, chemo-selective, heterogeneous catalyst, Reusable, Ru(II) immobilized SBA-15}, issn = {1566-7367}, doi = {10.1016/j.catcom.2017.10.016}, author = {Lazar, Anish and Betsy, K. J. and Vinod, C. P. and Singh, A. P.} } @article {46326, title = {Ag nanoparticles supported on a resorcinol-phenylenediamine-based covalent organic framework for chemical fixation of CO2}, journal = {Chemistry-An Asian Journal }, year = {2019}, month = {OCT}, type = {Article; Early Access}, abstract = {

Covalent organic frameworks are a new class of crystalline organic polymers possessing a high surface area and ordered pores. Judicious selection of building blocks leads to strategic heteroatom inclusion into the COF structure. Owing to their high surface area, exceptional stability and molecular tunability, COFs are adopted for various potential applications. The heteroatoms lining in the pores of COF favor synergistic host-guest interaction to enhance a targeted property. In this report, we have synthesized a resorcinol-phenylenediamine-based COF which selectively adsorbs CO2 into its micropores (12 angstrom). The heat of adsorption value (32 kJ mol(-1)) obtained from the virial model at zero-loading of CO2 indicates its favorable interaction with the framework. Furthermore, we have anchored small-sized Ag nanoparticles (approximate to 4-5 nm) on the COF and used the composite for chemical fixation of CO2 to alkylidene cyclic carbonates by reacting with propargyl alcohols under ambient conditions. Ag@COF catalyzes the reaction selectively with an excellent yield of 90 \%. Recyclability of the catalyst has been demonstrated up to five consecutive cycles. The post-catalysis characterizations reveal the integrity of the catalyst even after five reaction cycles. This study emphasizes the ability of COF for simultaneous adsorption and chemical fixation of CO2 into corresponding cyclic carbonates.

}, keywords = {CO2 capture, covalent organic frameworks, cyclic carbonates, Propargyl alcohols, silver nanoparticles}, issn = {1861-4728}, doi = {10.1002/asia.201901157}, author = {Chakraborty, Debanjan and Shekhar, Pragalbh and Singh, Himan Dev and Kushwaha, Rinku and Vinod, C. P. and Vaidhyanathan, Ramanathan} } @article {47176, title = {Aqueous-phase differentiation and speciation of Fe3+ and Fe2+ using water-stable photoluminescent lanthanide-based metal-organic framework}, journal = {ACS Applied Nano Materials}, volume = {2}, year = {2019}, month = {AUG}, pages = {5169-5178}, type = {Article}, abstract = {

Fe2+ is vital to O-2 transportation and photosynthesis regulated by oxidases and reductases. On the other hand, Fe3+ is detrimental due to its irreversible binding to O-2. Hence there is a need for selective identification of Fe3+ from aqueous systems in the presence of Fe2+. However, given their close chemical nature, it is not straightforward to differentiate them. Fe2+ and Fe3+ are typically sensed and differentiated using magnetic measurements, Mossbauer, X-ray absorption spectroscopy, or EXAFS, which are complex and equipment intensive techniques. In comparison, the fluorescence technique is advantageous in terms of time and accessibility. Although readily available lanthanide salts exhibit fluorescence, they are weak, and to serve as an optical probe, their luminescence has to be enhanced via ligand design. Hence we have designed a chromophoric ligand that can covalently bind to lanthanides and enhance its fluorescence intensity, and it binds selectively to Fe3+ through its nitrogen centers. It detects Fe3+ from low concentration (similar to 100 mu M) aqueous solutions, with fast response time (\<1 min) and with a detection limit of 3.6 ppm. Importantly, the Fe3+ adsorbed MOF can be readily reactivated for the next cycle by merely washing with an aqueous ascorbic acid solution and can be used for multiple cycles without any appreciable loss in activity. This makes the Ln-MOF an environmentally benign, cost-effective, scalable, and recyclable probe.

}, keywords = {Fe3+ differentiation and speciation, flexible ligand, fluorescent MOF, iron speciation, Metal-organic framework, water sorption}, issn = {2574-0970}, doi = {10.1021/acsanm.9b01047}, author = {Maity, Rahul and Chakraborty, Debanjan and Nandi, Shyamapada and Yadav, Ankit Kumar and Mullangi, Dinesh and Vinod, C. P. and Vaidhyanathan, Ramanathan} } @article {46167, title = {Au based Ni and Co bimetallic core shell nanocatalysts for room temperature selective decomposition of hydrous hydrazine to hydrogen}, journal = {ChemistrySelect}, volume = {4}, year = {2019}, month = {MAR }, pages = {2734-2740}, type = {Article}, abstract = {

Nickel and Cobalt bimetallic catalysts with Au as core metal has been synthesized and demonstrated for hydrazine decomposition reaction for producing hydrogen. Gold-cobalt and gold nickel bimetallic system belonging to the class of strained structures with high lattice mismatch of approximately 14\% are demonstrated for synergistic effects atypical of monometallic counterparts for the selective decomposition of hydrous hydrazine to H-2 with N-2 as the other product at room temperature.

}, keywords = {(HDR), Au@Co., Au@Ni., Bimetallic, catalyst., core, decomposition, Hydrazine, nanoparticles., reaction, shell}, issn = {2365-6549}, doi = {10.1002/slct.201900483}, author = {Jain, P. and Anila, K. A. and Vinod, C. P.} } @article {46320, title = {Mechanistic insights into the pathways of phenol hydrogenation on Pd nanostructures}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {7}, year = {2019}, month = {OCT}, pages = {17126-17136}, type = {Article}, abstract = {

Product selectivity in aqueous phase phenol hydrogenation on well-defined supported Pd nanostructures (spheres, cubes, and octahedra) was studied using defined experiments and density functional theory (DFT) simulations. On Pd spheres and octahedra, the reaction initially showed high selectivity (in the first 3 h, at 363 K and 5 bar H-2 pressure) toward the partially hydrogenated product cyclohexanone. On prolonged operation (\>20 h of reaction time), a shift in the product selectivity (up to 100\%) toward the completely hydrogenated product cyclohexanol was observed on Pd spheres and octahedra. In contrast, the reaction on Pd cubes, which only had {100} facets, showed a high selectivity (similar to 90\%) toward the product cyclohexanone even after 40 h, at the same reaction conditions. Since the {111} facets are expected to be the majority sites on a spherical particle, we attribute the selectivity trend observed on spherical Pd particles to be primarily controlled by the selectivity trend on the Pd{111} facets. This observation was further confirmed on performing the hydrogenation reaction on a mixture of Pd cube and Pd octahedron particles in a ratio of 25:75 (representing the site ratio of a spherical particle). DFT simulations provided a mechanistic insight into the reactivity of the two different facets ({100} and {111}) toward phenol hydrogenation. The calculations revealed that the selectivity significantly depended on the activation barriers involved in cyclohexanone hydrogenation on the Pd{111} facets (77 and 57 kJ/mol) as compared to those on the Pd{100} facets (97 and 101 kJ/mol).

}, keywords = {Cyclohexanol, cyclohexanone, facet-dependent reactivity, phenol hydrogenation}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.9b03392}, author = {Porwa, Govind and Gupta, Shelaka and Sreedhala, S. and Elizabeth, Joes and Ithan, Tuhin Suvra and Haider, M. Ali and Vinod, C. P.} } @article {46311, title = {Nickel-catalyzed C-H alkylation of indoles with unactivated alkyl chlorides: evidence of a Ni(i)/Ni(iii) pathway}, journal = {Chemical Science}, volume = {10}, year = {2019}, month = {NOV}, pages = {9493-9500}, type = {Article}, abstract = {

A mild and efficient nickel-catalyzed method for the coupling of unactivated primary and secondary alkyl chlorides with the C-H bond of indoles and pyrroles is described which demonstrates a high level of chemo and regioselectivity. The reaction tolerates numerous functionalities, such as halide, alkenyl, alkynyl, ether, thioether, furanyl, pyrrolyl, indolyl and carbazolyl groups including acyclic and cyclic alkyls under the reaction conditions. Mechanistic investigation highlights that the alkylation proceeds through a single-electron transfer (SET) process with Ni(i)-species being the active catalyst. Overall, the alkylation follows a Ni(i)/Ni(iii) pathway involving the rate-influencing two-step single-electron oxidative addition of alkyl chlorides.

}, issn = {2041-6520}, doi = {10.1039/c9sc01446b}, author = {Pandey, Dilip K. and Ankade, Shidheshwar B. and Ali, Abad and Vinod, C. P. and Punji, Benudhar} } @article {45528, title = {Nickel-catalyzed straightforward and regioselective C-H alkenylation of indoles with alkenyl bromides: scope and mechanistic aspect}, journal = {ACS Catalysis}, volume = {9}, year = {2019}, month = {JAN}, pages = {431-441}, type = {Article}, abstract = {

Nickel-catalyzed regioselective C-H bond alkenylation of indoles and related heteroarenes with alkenyl bromides is accomplished under relatively mild conditions. This method allows the straightforward synthesis of C-2 alkenylated indoles employing an air-stable and well-defined nickel catalyst, (bpy)NiBr2, providing a solution to the limitations associated with hydroindolation and oxidative alkenylation. The reaction conceded the coupling of indole derivatives with various alkenyl bromides, such as aromatic and heteroaromatics, alpha- and beta-substituted as well as exo- and endo-cyclic alkenyl compounds. An extensive mechanistic investigation, including controlled study, reactivity experiments, kinetics and labeling studies, and EPR and XPS analyses, highlights that the alkenylation proceeds through a single-electron transfer process comprising an odd-electron oxidative addition of alkenyl bromide. Furthermore, the alkenylation operates via a probable Ni(I)/Ni(III) pathway involving the rate-limiting C-H nickelation of indole.

}, keywords = {alkenylation, C-H activation, indoles, Mechanism, Nickel, single-electron transfer}, issn = {2155-5435}, doi = {10.1021/acscatal.8b04267}, author = {Jagtap, Rahul A. and Vinod, C. P. and Punji, Benudhar} } @article {45527, title = {Operando X-ray absorption spectroscopy study of the Fischer-Tropsch reaction with a Co catalyst}, journal = {Journal of Synchrotron Radiation}, volume = {26}, year = {2019}, month = {JAN}, pages = {137-144}, type = {Article}, abstract = {

This article describes the setting up of a facility on the energy-scanning EXAFS beamline (BL-09) at RRCAT, Indore, India, for operando studies of structure-activity correlation during a catalytic reaction. The setup was tested by operando X-ray absorption spectroscopy (XAS) studies performed on a Co-based catalyst during the Fischer-Tropsch reaction to obtain information regarding structural changes in the catalyst during the reaction. Simultaneous gas chromatography (GC) measurements during the reaction facilitate monitoring of the product gases, which in turn gives information regarding the activity of the catalyst. The combination of XAS and GC techniques was used to correlate the structural changes with the activity of the catalyst at different reaction temperatures. The oxide catalyst was reduced to the metallic phase by heating at 400 degrees C for 5h under H-2 at ambient pressure and subsequently the catalytic reaction was studied at four different temperatures of 240, 260, 280 and 320 degrees C. The catalyst was studied for 10h at 320 degrees C and an attempt has been made to understand the process of its deactivation from the XANES and EXAFS results.

}, keywords = {catalysis, EXAFS, Fischer-Tropsch reaction, in situ studies, structure-activity correlation, XANES}, issn = {1600-5775}, doi = {10.1107/S1600577518015588}, author = {Nayak, Chandrani and Jain, Preeti and Vinod, C. P. and Jha, S. N. and Bhattacharyya, D.} } @article {45628, title = {Role of Li+ and Fe3+ in modified ZnO: Structural, vibrational, opto-electronic, mechanical and magnetic properties}, journal = {Ceramics International}, volume = {45}, year = {2019}, month = {JAN}, pages = {7232-7243}, type = {Article}, abstract = {When Fe is doped in ZnO, a situation of charge imbalance is created due to the higher charge of Fe3+. A charge balance may be obtained by co-doping Li+0.5Fe3+0.5 combinations. A solid solution of Zn1-x(Fe0.5Li0.5)xO (0 <= x <= 0.03125) is synthesized with this viewpoint. The crystallites belong to a wurtzite P63mc space group, with lattice parameters a, b and c increasing nominally for x = 0.0156 and thereafter remaining invariant. The size varies in the range ~ 60{\textendash}142 nm. Interstitials of Li and Zn ions are formed. Along with Fe3+ substitution these defects are reasons for O interstitials. These oxygen interstitials increase the red emission while reduction of oxygen vacancies reduces the green emission. These point defects create structural distortion and strain which can generate Zn vacancies. Bandgap reduces due to shallow defects. Mid-bandgap states due to oxygen interstitials and Fe 3d-O 2p hybridization result in NIR emission. On the other hand the crystal surface deforms due to Li addition which hardens the materials. A weak ferromagnetism appears at very low temperature which is enhanced by Li+ addition. Long range exchange mechanism between Fe3+ ions appears in the samples, mediated by magnetic polarons due to point defects.}, keywords = {hardness, NIR emission, Shallow and deep level defects, Weak ferromagnetism, ZnO}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2019.01.004}, author = {Bajpai, G. and Moirangthem, I. and Sarkar, S. and Barman, S. R. and Vinod, C. P. and Bajpai, S. and Riyajuddin, S. and Ghosh, K. and Basaula, D. R. and Khan, M. and Liu, S. -W. and Biring, S. and Sen, S.} } @article {46143, title = {Surfactant free synthesis of Au@Ni core-shell nanochains in aqueous medium as efficient transfer hydrogenation catalyst}, journal = {Applied Catalysis A-General}, volume = {575}, year = {2019}, month = {APR }, pages = {93-100}, type = {Article}, abstract = {

A surfactant free aqueous phase synthesis method is reported for the generation of highly lattice mismatched Au@Ni core-shell nanochains without using any expensive and hazardous organic ligands. As synthesised Au@Ni nanochain structures showed high thermal stability and bulk oxidation resistance up to 300 degrees C. In situ near ambient pressure XPS (NAPXPS) analysis has been done for the bare Au@Ni nanochain surfaces under oxygen atmosphere and at different temperatures which showed evidence for the surface oxidation resistance of naked Au@Ni nanochains up to 200 degrees C. Ligand or capping agent free Au@Ni nanochain surfaces are found to be highly active for transfer hydrogenation of acetophenone to 1-phenyl ethanol an important commodity in perfumery industry.

}, keywords = {Au@Ni nanochains, core-shell, NAPXPS, Surfactant free, synergistic effects, transfer hydrogenation}, issn = {0926-860X}, doi = {10.1016/j.apcata.2019.01.017}, author = {Vysakh, A. B. and Shebin, K. J. and Jain, Ruchi and Sumanta, P. and Gopinath, Chinnakonda S. and Vinod, C. P.} } @article {46688, title = {CO2 hydrogenation to formate by palladium nanoparticles supported on N-incorporated periodic mesoporous organosilica}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {8}, year = {2020}, month = {OCT }, pages = {14765-14774}, type = {Article}, abstract = {

Development of a heterogeneous catalyst capable of selective transformation of CO2 to valuable products still remains a challenge. In this article, we account for the surfactant-directed synthesis of a new framework-incorporated nitrogen-containing periodic mesoporous organosilica nanosphere (NPMO). A thoroughly characterized N-incorporated hybrid PMO was utilized as a platform for stabilizing well-dispersed and easily accessible Pd nanoparticles (Pd-NPMO) without using any stabilizing agents or expensive dendrimers. Further, this bifunctional hybrid catalyst has been demonstrated to heterogeneously catalyze aqueous phase CO2 hydrogenation (CO2/H-2 ratio 1:3) for the direct synthesis of formate under 4 MPa pressure and at 100 degrees C. To validate the superior performance of the Pd-NPMO catalyst, we compared the activity with Pd-SBA-15 catalysts, and the results showed a 10-fold increase in turnover frequency of 108 h(-1) using Pd on NPMO which envisaged the crucial role of nitrogen sites in this catalyst to boost the CO2 valorization to formate.

}, keywords = {CO2 hydrogenation, Formic acid synthesis, Hybrid silica, Pd nanoparticles, PMO}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.0c03860}, author = {Betsy, K. J. and Lazar, Anish and Pavithran, Anjuna and Vinod, C. P.} } @article {46923, title = {Dynamics in amine-functionalized mesoporous hybrid materials probed through deuterium magic angle spinning NMR and molecular dynamic simulations}, journal = {Journal of Physical Chemistry C}, volume = {124}, year = {2020}, month = {MAR}, pages = {6154-6170}, type = {Article}, abstract = {

We present a deuterium magic angle spinning (MAS) NMR study on two widely used hybrid materials (3-glycidyloxy propyl)trimethoxysilane (3-GPTMS) and 3-(trimethoxysilyl)propyl methacrylate (3-MATMS) grafted on SBA-15. Methylene-deuterated diamine as a pendent group is anchored to GPTMS (O3Si-CH2-CH2-CH2-O-CH2-CH(OH)- CH2-NH-CD2-CD2-NH2) and MATMS (O3Si-CH2-CH2-CH2-O-C(N-CD2-CD2-NH2)-C(CH3)=-CH2) postgrafting. Proton and deuterium solid state NMR experiments under MAS were performed at two hydration levels and temperatures ranging from 253 to 315 K. Deuterium spectra were deconvoluted into three A Dr, components with different average quadrupolar parameters: a relatively rigid component arising from local or librational motion of C-H-2(2) corresponding to {\textquoteleft}{\textquoteleft}small angle{\textquoteright}{\textquoteright} jumps, an intermediate dynamic component, and a large amplitude dynamic component. Population ratios of rigid versus dynamic components show that diamine-MATMS is more rigid when compared with diamine-GPTMS at high hydration. The role of the length of the linkers, steric hindrance, grafting concentration, etc. in defining mobility is investigated. Finally, by correlating proton and deuterium MAS NMR spectral analysis, the role of a few water molecules in inducing dynamics of the linkers was investigated. Molecular dynamic (MD) simulations support the experimental analysis. MD simulations indicate different types of mobility arising from the same molecular binding configuration of diamine-MATMS. Dynamics induced by a few hydroxyls on the pore surface accessible to the linker, various molecular conformations, and stabilization of the linker through hydrogen bonding with the surface, derived from MD simulations, are discussed.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.9b11948}, author = {Veena, V. S. and Kavya, I and Lazar, A. and Vinod, C. P. and Ajithkumar, T. G. and Jayanthi, S.} } @article {46837, title = {Engineering pore morphology using silica template route over mesoporous cobalt oxide and its implications in atmospheric pressure carbon dioxide hydrogenation to olefins}, volume = {19}, year = {2020}, month = {JUN}, pages = {100586}, type = {Article}, abstract = {

Highly ordered mesoporous cobalt oxides (denoted as m-Co-KIT-6 and m-Co-SBA-15) with three dimensional and two dimensional pore morphology respectively have been synthesized using 3D KIT-6, and 2D SBA-15 as silica template via nanocasting route. CO2 hydrogenation activity was evaluated for these mesoporous materials under atmospheric pressure conditions. In comparison to nanoparticles of cobalt oxide (Co3O4-nano), mesoporous catalysts showed excellent activity for CO2 hydrogenation due to their higher number of exposed active sites and lower mass diffusion limitations. The ordered mesoporous structure of Co3O4 catalysts favored the chain growth of carbon atoms for the production of C2+ hydrocarbons while Co3O4 nanoparticles showed strong selectivity toward CH4. High selectivity for C2+ (similar to 25\%) was obtained for both m-Co-KIT-6 and m-Co-SBA-15 catalysts at 320 degrees C. In addition, the 3D pore structure of m-Co-KIT-6 catalyst exclusively formed more olefins (54.9\%) fraction. (C) 2020 Published by Elsevier Ltd.

}, keywords = {CO2 hydrogenation, Mesoporous CO3O4, Olefin fraction, Pore morphology, Silica hard template}, issn = {2352-9407}, doi = {10.1016/j.apmt.2020.100586}, author = {Gupta, Sharad and Ciotonea, Carmen and Royer, Sebastien and Dacquin, Jean-Philippe and Vinod, C. P.} } @article {46798, title = {Iron-catalyzed C(sp(2))-H alkylation of indolines and benzo[h]quinoline with unactivated alkyl chlorides through chelation assistance}, journal = {ACS Catalysis}, volume = {10}, year = {2020}, month = {JUL }, pages = {7312-7321}, type = {Article}, abstract = {

Regioselective C-H bond alkylation of indolines and benzo[h]quinoline with a wide range of unactivated and highly demanded primary and secondary alkyl chlorides is accomplished using a low-cost iron catalyst. This reaction tolerates diverse functionalities, such as C(sp(2))-Cl, fluoro, alkenyl, silyl, ether, thioether, pyrrolyl, and carbazolyl groups including cyclic and acyclic alkyls as well as alkyl-bearing fatty-alcohol and polycyclic-steroid moieties. The demonstrated iron-catalyzed protocol proceeded via either a five-membered or a six-membered metallacycle. Intriguingly, the C-7-alkylated indolines can be readily functionalized into free-NH indolines/indoles and tryptamine derivatives. A detailed mechanistic investigation highlights the participation of an active Fe(I) catalyst and the involvement of a halogen-atom transfer process via a single-electron-based mechanism. Deuterium labeling and kinetics analysis indicate that the C-H metalation of indoline is the probable turnover-limiting step. Overall, the experimental and theoretical studies supported an Fe(I)/Fe(III) pathway for the alkylation reaction comprising the two-step, one-electron oxidative addition of alkyl chloride.

}, keywords = {alkyl chlorides, Alkylation, C-H activation, chelation assistance, indolines, iron}, issn = {2155-5435}, doi = {10.1021/acscatal.0c02030}, author = {Jagtap, Rahul A. and Samal, Pragnya Paramita and Vinod, C. P. and Krishnamurty, Sailaja and Punji, Benudhar} } @article {46802, title = {Nanocrystalline Ag3PO4 for sunlight- and ambient air-driven oxidation of amines: high photocatalytic efficiency and a facile catalyst regeneration strategy}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {JUL}, pages = {29324-29334}, type = {Article}, abstract = {

Selective oxidation of amines to imines using sunlight as clean and renewable energy source is an important but challenging chemical transformation because of high reactivity of the generated imines and lack of visible light-responsive materials with high conversion rates. In addition, oxygen gas has to be purged in the reaction mixture in order to increase the reaction efficiency which, in itself, is an energy-consuming process. Herein, we report, for the first time, the use of Ag3PO4 as an excellent photocatalyst for the oxidative coupling of benzyl amines induced by ambient air in the absence of any external source of molecular oxygen at room temperature. The conversion efficiency for the selective oxidation of benzyl amine was found to be greater than 95\% with a selectivity of \>99\% after 40 min of light irradiation indicating an exceptionally high conversion efficiency with a rate constant of 0.002 min(-1), a turnover frequency of 57 h(-1), and a quantum yield of 19\%, considering all of the absorbed photons. Ag3PO4, however, is known for its poor photostability owing to a positive conduction band position and a favorable reduction potential to metallic silver. Therefore, we further employed a simple catalyst regeneration strategy and showed that the catalyst can be recycled with negligible loss of activity and selectivity.

}, keywords = {amine oxidation, energy harvesting, nanocrystalline Ag3PO4, Photocatalysis, regeneration strategy}, issn = {1944-8244}, doi = {10.1021/acsami.0c05961}, author = {Garg, Reeya and Mondal, Sanjit and Sahoo, Lipipuspa and Vinod, C. P. and Gautam, Ujjal K.} } @article {46777, title = {Role of B site ions in bifunctional oxygen electrocatalysis: a structure-property correlation study on doped Ca(2)Fe(2)O(5)brownmillerites}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, year = {2020}, month = {JUL }, pages = {15520-15527}, type = {Article}, abstract = {

The role of B site doping with transition metals in brownmillerites, a perovskite related family of compounds, in bifunctional oxygen electrocatalysis,viz., simultaneous reduction and evolution reactions, is analysed. Ca2Fe1.9M0.1O5(M = Mn, Co, Ni, and Cu) is synthesised and structurally characterised by powder XRD and Rietveld refinement. Valence states of the surface B site ions are identified by X-ray photoelectron spectroscopy. Bifunctional oxygen electrochemistry is studied with the RDE and RRDE techniques and correlated with the structural and electronic parameters like oxygen non-stoichiometry and B site catalytic activity. Since the widely accepted electronic descriptors like e(g)filling may not be sufficient for explaining the bifunctional activity, B site electron donating capability as well as the extent of oxygen vacancies enhancing O(2)adsorption is also considered. Such structural parameters are also found to influence both the ORR and OER and based on this, Ni doping is proposed as advantageous for the bifunctional activity.

}, issn = {1463-9076}, doi = {10.1039/d0cp02391d}, author = {Thundiyil, Shibin and Vinod, C. P. and Kurungot, Sreekumar and Devi, R. Nandini} } @article {47317, title = {Role of exposed crystal facets in the atmospheric pressure CO hydrogenation on Co3O4}, journal = {Nano-Structures \& Nano-Objects}, volume = {23}, year = {2020}, month = {JUL}, type = {Article}, abstract = {

Co3O4 nanostructures with different exposed planes are studied for atmospheric pressure CO hydrogenation. Existence of different facets is characterized by HR-TEM and found Co3O4 - NSP (nanospheres) expose (112) facet, NB (nanobelts) exhibit (110) plane and (100) is the dominant surface facet in NC (nanocubes). Different catalytic activity is demonstrated by the specific facet of Co3O4 catalysts. CO hydrogenation is facet dependent and the catalytic activity follows the order of Co3O4-NB \> Co3O4-NC \> Co3O4-NSP.

}, doi = {10.1016/j.nanoso.2020.100504}, author = {Jain, Preeti and Gupta, Sharad and Vinod, C. P.} } @article {46715, title = {Spectroscopic evidences for the size dependent generation of pd species responsible for the low temperature CO oxidation activity on Pd-SBA-15 nanocatalyst}, journal = {Applied Catalysis B-Environmental}, volume = {272}, year = {2020}, month = {SEP }, pages = {118934}, type = {Article}, abstract = {

A comprehensive size dependent CO oxidation activity has been demonstrated for Pd-SBA-15 catalysts with Pd NPs of varying sizes such as 1-2, 4-6 and 7-10 nm. Pd-SBA-15 catalyst with smallest sized NPs (Pd-S-N) has been synthesized by modified deposition precipitation method recently developed in our lab. Pd-S-N catalyst (reduced at 400 degrees C) demonstrated CO oxidation activity with lower light off temperature (50 degrees C), clearly one of the best reported for a Pd-silica system. A detailed XPS and in-situ DRIFTS analyses further supported by XAS and DFT calculations reveal the presence of easily decomposable highvalent Pd-oxide on co-ordinatively unsaturated Pd sites (Pdcus). Weak binding of CO on Pdcus sites in small Pd NPs leaving sites for oxygen activation is attributed to the low temperature activity of Pd-S-N for CO oxidation.

}, keywords = {CO oxidation, high-valent Pd species, Pd nanoparticles, SBA-15, under coordinated Pd atoms}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2020.118934}, author = {Soni, Yogita and Pradhan, Sumanta and Bamnia, Mahesh K. and Yadav, A. K. and Jha, S. N. and Bhattacharyya, D. and Khan, Tuhin Suvra and Haider, M. A. and Vinod, C. P.} } @article {46969, title = {Stress-induced electronic structure modulation of manganese-incorporated Ni2P leading to enhanced activity for water splitting}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {FEB}, pages = {1271-1278}, type = {Article}, abstract = {

The cornerstone of the emerging hydrogen economy is hydrogen production by water electrolysis with concomitant oxygen generation. Incorporating a third element in metal phosphides can tune the crystalline and electronic structure, hence improving the electrocatalytic properties. In this work, Mn-doped Ni2P with varying ratios of Mn and Ni has been explored as excellent catalysts for water splitting. A complete cell made of the best catalyst Ni1.5Mn0.5P electrodes showed low voltage of 1.75 V at a current density of 10 mA cm(-2) due to enhanced electrical conductivity, induction of tensile stress, enhanced electrochemical surface area, and increased electric dipole upon Mn incorporation.

}, keywords = {Electronic Structure, hydrogen evolution reaction, Oxygen Evolution Reaction, phosphides, water splitting}, issn = {2574-0962}, doi = {10.1021/acsaem.9b02097}, author = {Sarkar, Shreya and Dheer, Lakshay and Vinod, C. P. and Thapa, Ranjit and Waghmare, V. Umesh and Peter, Sebastian C.} } @article {46670, title = {Wavelength dependent luminescence decay kinetics in {\textquoteleft}quantum-confined{\textquoteright} g-C(3)N(4)nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling}, journal = {Journal of Materials Chemistry A}, volume = {8}, year = {2020}, month = {OCT }, pages = {20581-20592}, type = {Article}, abstract = {

Serendipitous observations offer newer insights into materials properties. Here we describe g-C(3)N(4)nanosheets exhibiting remarkably blue-shifted photoluminescence within the 390-580 nm range centred at 425 nm which matches more closely with its {\textquoteleft}quantum-dots{\textquoteright}, and yet is excitation-wavelength independent. Moreover, surprisingly, the luminescence decay becomes increasingly slow at higher emission wavelengths, by up to 10 times. The nanosheets absorb only a fraction of visible-light. To improve this, when we designed a nanocomposite of g-C(3)N(4)and Au nanoparticles (NPs), it retained the PL characteristics and also exhibited excellent light-harvesting and photocatalytic efficiency for benzylamine (BA) oxidation. The surface plasmon resonance of the Au NPs is responsible for the high visible-light response and assisting the reaction by the {\textquoteleft}hot-electron{\textquoteright} injection mechanism, while an uncharacteristic, pronounced co-catalytic effect by them further improves the efficiency. The conversion is 98\% with \>99\% selectivity over 1.5 h of natural sunlight and open-air, probably the highest efficiency for BA photo-oxidation reactions. Even though such a dual role by plasmonic NPs has remained unscrutinized, we argue that the charge-transfer processes for the {\textquoteleft}hot-carrier{\textquoteright} injection and co-catalytic events are well-separated in time due to a much slower photon incident frequency on a catalyst particle, enabling both to occur simultaneously in the same particle.

}, issn = {2050-7488}, doi = {10.1039/d0ta08001b}, author = {Mondal, Sanjit and Sahoo, Lipipuspa and Vaishnav, Yuvraj and Mishra, Samita and Roy, Raj Sekhar and Vinod, C. P. and De, Arijit K. and Gautam, Ujjal K.} } @article {47438, title = {Autophagy and unique aerial oxygen harvesting properties exhibited by highly photocatalytic carbon quantum dots}, journal = {Carbon}, volume = {181}, year = {2021}, month = {AUG}, pages = {16-27}, type = {Article}, abstract = {

Plastic pollution is a serious threat to the environment as they are not bio-degradable. Herein using waste-polyethylene, we report two inter-related important findings. First that they can be converted economically and completely into highly photocatalytic carbon quantum-dots (CQDs) using H2O2\ as a residue-free oxidant in an acid medium, and they have the ability to enrich a reaction medium with an extraordinary amount of molecular oxygen harvested from the air so that no separate oxygen source is needed while carrying out facile photocatalytic\ oxidation reactions. Second, when they are not performing any photocatalytic reaction, they exhibit self-sensitized photo-oxidation to convert themselves completely to CO2\ in the presence of sunlight, a phenomenon that we term as {\textquoteleft}CQD-autophagy{\textquoteright} by drawing parallels to the death of useless-cells in the body. Such extinction from the reaction media is unique as no other material is known to do so and advantageous because the removal of carbon-dots from a solution is rather inefficient from an industry-viewpoint due to their high solubility. Instead, the inexpensive CQDs can be discarded casually with the notion that they will gradually get eliminated from the environment.

}, keywords = {Carbon dots, Oxygen-enrichment, Photocatalytic oxidation, Self-sensitized photo-oxidation}, issn = {0008-6223}, doi = {10.1016/j.carbon.2021.04.054}, author = {Mondal, Sanjit and Vinod, C. P. and Gautam, Ujjal K.} } @article {47037, title = {Conductive interface promoted bifunctional oxygen reduction/evolution activity in an ultra-low precious metal based hybrid catalyst (vol 57, pg 1951, 2021)}, journal = {Chemical Communications}, volume = {57}, year = {2021}, month = {MAR }, pages = {2824}, type = {Correction}, issn = {1359-7345}, doi = {10.1039/d1cc90088a}, author = {Sarkar, Shreya and Varghese, Merin and Vinod, C. P. and Peter, Sebastian C.} } @article {47060, title = {Conductive interface promoted bifunctional oxygen reduction/evolution activity in an ultra-low precious metal based hybrid catalyst}, journal = {Chemical Communications}, volume = {57}, year = {2021}, month = {FEB}, pages = {1951-1954}, type = {Article}, abstract = {

Ultra low PtPd alloy deposited on Ni12P5 nanostructures (PtPd/Ni12P5) exhibited enhanced ORR activity (onset: 1.003 V and E-1/2:0.95 V) on par with commercial Pt/C and superior OER activity with 81\% reduction of the precious metal compared to the commercial catalyst.

}, issn = {1359-7345}, doi = {10.1039/d0cc08225b}, author = {Sarkar, Shreya and Varghese, Merin and Vinod, C. P. and Peter, Sebastian C.} } @article {47746, title = {CuO as a reactive and reusable reagent for the hydrogenation of nitroarenes}, journal = {Applied Catalysis B-Environmental}, volume = {297}, year = {2021}, month = {NOV}, pages = {120417}, type = {Article}, abstract = {{Copper oxide (CuO) is used as a reusable solid reagent for hydrogenation of nitroarenes to aminoarenes. The use of CuO resulted in 100 \% conversion of 2.9 mmol of nitrobenzene to aniline in 45 s at room temperature using hydrazine hydrate as the reducing agent. During the reaction, CuO is converted to inactive metallic Cu which can be regenerated to active CuO by thermal oxidation. DFT simulations indicated facile formation of oxygen vacancies (EO}, keywords = {Copper vacancy, CuO, Hydrogenation, Nitroarene reduction, Oxygen defects, Reactive solids}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2021.120417}, author = {Rajendran, K. and Pandurangan, N. and Vinod, C. P. and Khan, Tuhin S. and Gupta, Shelaka and Haider, M. Ali and Jagadeesan, D.} } @article {47028, title = {Facile transfer of excited electrons in Au/SnS2 nanosheets for efficient solar-driven selective organic transformations}, journal = {Applied Catalysis B-Environmental}, volume = {286}, year = {2021}, month = {JUN }, pages = {119927}, type = {Article}, abstract = {

Solar driven aerial oxidation processes have gained importance in organic transformations leading to the development of many nanocrystalline photocatalysts. Although such nanomaterials have many potential advantages, they often underperform due to poor visible light absorption and rapid recombination of excitons. Incorporation of plasmonic nanoparticles (NPs) on the catalyst surfaces can extend their response to visible light and improve photocatalytic efficiency by the {\textquoteleft}hot-electron{\textquoteright} injection mechanism. Nanostructures of SnS2 too absorb a part of the visible light to induce many photocatalytic reactions, though their ability to perform the selective and controlled organic transformations has not yet been observed. Herein, we demonstrate the first example of such transformation with the oxidative coupling of various benzylamine (BA) derivatives to imines under ambient conditions using SnS2 nanosheets (NSs). The reaction rate improves manifold and shows similar to 98 \% conversion (\>99 \% selectivity) in 2 h under direct sunlight and open-air when the NSs were decorated with 1.5 wt\% Au NPs on (Au/SnS2), making it one of the best catalysts for this reaction. We found that the large enhancement in activity upon Au loading is accompanied by a noticeable change in photo-induced charge accumulation behaviour in Au/SnS2 from the usual {\textquoteleft}{\textquoteleft}spike and overshoot{\textquoteright}{\textquoteright} one and contributed by facile transfer of excited electrons across the Au-SnS2 heterojunction in which Au NPs act as both sources and sinks for the photo-excited electrons. Finally, a detailed mechanism of the oxidation reaction has been proposed.

}, keywords = {Benzylamine oxidation, Hot-electron injection, Plasmonic nanoparticle, SnS2 nanosheet, Solar energy harvesting}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2021.119927}, author = {Mondal, Sanjit and Sahoo, Lipipuspa and Vinod, C. P. and Gautam, Ujjal K.} } @article {47634, title = {Role of metal-support interaction for atmospheric pressure CO2 hydrogenation over Pd/(Ti)-SBA-15 catalyst: effect of titanium composition on products selectivity}, journal = {Molecular Catalysis}, volume = {511}, year = {2021}, month = {JUL}, pages = {111732}, type = {Article}, abstract = {The potential role of metal-support interaction for tuning the product selectivity during atmospheric pressure CO2 hydrogenation has been demonstrated on Pd/(Ti)-SBA-15 catalyst. Highly dispersed Pd NPs on SBA-15 (Pd/ SBA-15) was synthesized and further modified with titanium of varying composition. Comparison of catalytic activity of Pd/Ti-SBA-15 with its counterparts (Pd/SBA-15 and Pd/TiO2) illustrated the significance of strong PdTi interface in this catalyst and its role in tuning the product selectivity of CO2 hydrogenation. The generation of an ample amount of oxygen vacancies in the Pd/Ti-SBA-15 catalyst with maximum metallic Pd sites in close vicinity of Ti is proposed to boost the CO2 hydrogenation activity.}, keywords = {CO2 hydrogenation, Metal-support interaction, Modified deposition precipitation, oxygen vacancies, Titanosilicates}, issn = {2468-8231}, doi = {10.1016/j.mcat.2021.111732}, author = {Soni, Yogita and Gupta, Sharad and Vinod, C. P.} } @article {47729, title = {Structure-tailored non-noble metal-based ternary chalcogenide nanocrystals for pt-like electrocatalytic hydrogen production}, journal = {ChemSusChem}, volume = {14}, year = {2021}, month = {AUG }, pages = {3074-3083}, type = {Article}, abstract = {A facile microwave-assisted strategy was employed to synthesize Ni3Bi2S2 nanocrystals. Variation in the synthesis conditions tuned the composition of monoclinic and orthorhombic phases of Ni3Bi2S2. The electrochemical hydrogen evolution activity of the catalyst with highest percentage of monoclinic phase demonstrated a negligible onset potential of only 24 mV close to that of state-of-the-art Pt/C with an overpotential as low as 88 mV. Density functional theory calculations predicted the monoclinic phase exhibit the lowest adsorption free energy corresponding to hydrogen adsorption (Delta GadsH*) and, therefore, the highest hydrogen evolution activity amongst the considered phases. The quasi-2D structure of monoclinic phase facilitated an increased charge-transfer between Ni and Bi, favoring the downward shift of the d-band center to enhance the catalytic activity.}, keywords = {charge transfer, electrocatalysis, hydrogen evolution reaction, Nanomaterials, ternary chalcogenides}, issn = {1864-5631}, doi = {10.1002/cssc.202100967}, author = {Sarkar, Shreya and Rawat, Abhishek and Das, Tisita and Gaboardi, Mattia and Chakraborty, Sudip and Vinod, C. P. and Peter, Sebastian C.} } @article {47450, title = {Unprecedented stability in Au@Co core-shell bimetallic catalyst supported on SBA-15 (Au@Co/SBA-15) for atmospheric pressure CO hydrogenation}, journal = {Materials Today Sustainability }, volume = {13}, year = {2021}, month = {SEP}, pages = {100068}, type = {Article}, abstract = {

Bimetallic nanoparticles demonstrating\ synergistic effect\ (electronic or geometric modification) often show distinct chemical and physical properties compared with the parent metals. In catalysis, this provides opportunities to engineer solid materials with appreciable activity, selectivity, and stability. In the present study, we have synthesized Au@Co core{\textendash}shell bimetallic nanoparticles by colloidal synthesis approach with a focus to study and explore the synergistic effect between Au and Co in Au@Co\ bimetallic catalyst\ supported on SBA-15 on\ Fischer Tropsch\ (FT) reaction. The deactivation of catalyst is a significant drawback in CO hydrogenation (syngas conversion/FT synthesis), and the present study provides the design of a new material, which resists the surface cobalt oxide formation\ and inactive coke formation and gives efficient CO conversion with high stability.

}, doi = {10.1016/j.mtsust.2021.100068}, author = {Jain, P. and Chimote, M. and Vinod, C. P.} } @article {47105, title = {Unveiling the roles of lattice strain and descriptor species on pt-like oxygen reduction activity in Pd-Bi catalysts}, journal = {ACS Catalysis}, volume = {11}, year = {2021}, month = {JAN}, pages = {800-808}, type = {Article}, abstract = {

A facile non-template-assisted mechanical ball milling technique was employed to generate a PdBi alloy catalyst. The induced lattice strain upon the milling time caused a shift of the d-band center, thereby enhancing the oxygen reduction reaction (ORR) catalytic activity. Additionally, the Pd-O reduction potential and adsorbed OH coverage used as descriptors stipulated the cause of the enhanced ORR activity upon the increased milling interval. Redox properties of surface Pd are directly correlated with a positive shift in the Pd-O reduction potential and OH surface coverage. Hence, by deconvoluting the lattice strain and the role of the descriptor species we achieved a catalyst system with a specific activity 5.4X higher than that of commercial Pt/C, as well as an improved durability. The experimental observation is well-corroborated by a theoretical simulation done by inducing strain to the system externally.

}, keywords = {charge-transfer, electrocatalysis, fuel cell, Lattice strain, oxygen reduction, Pt-like activity}, issn = {2155-5435}, doi = {10.1021/acscatal.0c03415}, author = {Sarkar, Shreya and Ramarao, S. D. and Das, Tisita and Das, Risov and Vinod, C. P. and Chakraborty, Sudip and Peter, Sebastian C.} } @article {48157, title = {Morphology-tuned Pt3Ge accelerates water dissociation to industrial-standard hydrogen production over a wide pH range}, journal = {Advanced Materials}, volume = {34}, year = {2022}, month = {JUL}, pages = {2202294}, type = {Article}, abstract = {

The discovery of novel materials for industrial-standard hydrogen production is the present need considering the global energy infrastructure. A novel electrocatalyst, Pt3Ge, which is engineered with a desired crystallographic facet (202), accelerates hydrogen production by water electrolysis, and records industrially desired operational stability compared to the commercial catalyst platinum is introduced. Pt3Ge-(202) exhibits low overpotential of 21.7 mV (24.6 mV for Pt/C) and 92 mV for 10 and 200 mA cm(-2) current density, respectively in 0.5 m H2SO4. It also exhibits remarkable stability of 15 000 accelerated degradation tests cycles (5000 for Pt/C) and exceptional durability of 500 h (@10 mA cm(-2)) in acidic media. Pt3Ge-(202) also displays low overpotential of 96 mV for 10 mA cm(-2) current density in the alkaline medium, rationalizing its hydrogen production ability over a wide pH range required commercial operations. Long-term durability (\>75 h in alkaline media) with the industrial level current density (\>500 mA cm(-2)) has been demonstrated by utilizing the electrochemical flow reactor. The driving force behind this stupendous performance of Pt3Ge-(202) has been envisaged by mapping the reaction mechanism, active sites, and charge-transfer kinetics via controlled electrochemical experiments, ex situ X-ray photoelectron spectroscopy, in situ infrared spectroscopy, and in situ X-ray absorption spectroscopy further corroborated by first principles calculations.

}, keywords = {Electrochemistry, hydrogen production, intermetallics, water electrolysis}, issn = {0935-9648}, doi = {10.1002/adma.202202294}, author = {Mondal, Soumi and Sarkar, Shreya and Bagchi, Debabrata and Das, Tisita and Das, Risov and Singh, Ashutosh Kumar and Prasanna, Ponnappa Kechanda and Vinod, C. P. and Chakraborty, Sudip and Peter, Sebastian C.} } @article {48178, title = {{\textquoteleft}Self-activating{\textquoteright} Bi3TaO7-Bi4TaO8Br photocatalyst and its use in the sustainable production of pro-fluorophoric rhodamine-110}, journal = {Green Chemistry}, volume = {24}, year = {2022}, month = {JUL}, pages = {5514-5523}, type = {Article}, abstract = {

We counter two common notions that (i) photocatalysts are likely to degrade during use with barely any strategy to counter it and (ii) rhodamine-B (RhB) photo-degradation lacks any useful or commercial prospects even after 53 years of its discovery by developing a photocatalyst that continues to improve its activity for similar to 300 h due to a leaching induced {\textquoteleft}self-activation{\textquoteright} process. Rhodamine-110 (Rh110) is a widely used pro-fluorophore in biological studies. However, its commercial production is highly challenging due to the formation of various side-products originating from the presence of the two labile amino side-groups that induce the pro-fluorophore activity, leading to purification difficulties, low yield, and unusually high costs. Herein, we demonstrate a facile strategy to produce pure Rh110 using extremely inexpensive RhB and Bi3TaO7-Bi4TaO8Br heterostructures as a catalyst in sunlight. The catalyst is not just stable over 30 catalytic cycles but also gets activated continuously in successive cycles to produce a reaction yield as high as 88\%. The role of the heterostructure, the origin of surface activation, and the RhB -\> Rh110 transformation mechanism have been established. Based on 150 days of sunlight experiments, large-scale production prospects (similar to 4000 times scale-up) and isolation of Rh110 have also been realized, paving a novel way for its production by anyone, inexpensive biological essaying, and device fabrication. Continuously improving catalysts are unknown and compensatory leaching of metal atoms from the catalyst surface may pave the way to realize them.

}, issn = {1463-9262}, doi = {10.1039/d2gc01574a}, author = {Banoo, Maqsuma and Chatterjee, Kaustav and Mondal, Sanjit and Vinod, C. P. and Gautam, Ujjal K.} } @article {47998, title = {Single-step insertion of M-Nx moieties in commercial carbon for sustainable bifunctional electrocatalysis: mapping insertion capacity, mass loss, and carbon reconstruction}, journal = {Carbon}, volume = {196}, year = {2022}, month = {AUG}, pages = {1001-1011}, type = {Article}, abstract = {

Atomically dispersed earth-abundant metals in N-doped carbon (M-N-Cs) have emerged as a new class of electroactive materials that can match not only the performance of the precious metals but can catalyze both the cathodic and the anodic reactions due to their bifunctional behaviour. This inspires the development of simpler strategies for scale-up production since the existing ones rely on precursors whose commercial viability is not yet ascertained. Herein, we demonstrate the insertion prospects of M-Nx (M = Fe, Co, Ni) moieties, the electrocatalytic centers in the M-N-Cs, into commercial carbon to establish that a single-step heating of the inexpensive precursors is sufficient to generate bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with efficiencies that bypass the majority of the known catalysts. Further importantly, we quantify both the ORR and OER trends and the metal insertion limits for each metal while maintaining an atomic dispersion, without the formation of surface migration-induced clustering, because such clustering is inevitable in the existing processes to necessitate an extra acid-leaching step to remove them. We further quantify and explain for each metal a negative mass balance originating from anomalous mass loss of both metal and carbon content, and a massive reconstruction of the carbon backbone catalyzed by the very metal, an event documented for the first time though it ought to be associated with other M-N-C syntheses too. The study establishes an incredibly simple and inexpensive strategy for the realization of M-N-Cs and outlines the parameters to be considered during mass-production.

}, keywords = {Bifunctional catalysis, Carbon reconstruction, Commercial carbon, Metal insertion, Oxygen electrocatalysis}, issn = {0008-6223}, doi = {10.1016/j.carbon.2022.06.008}, author = {Garg, Reeya and Sahoo, Lipipuspa and Kaur, Komalpreet and Vinod, C. P. and Gautam, Ujjal K.} } @article {48098, title = {Strain-enhanced phase transformation of iron oxide for higher alcohol production from CO2}, journal = {ACS Catalysis}, volume = {12}, year = {2022}, month = {SEP}, pages = {11118-11128}, type = {Article}, abstract = {

Conversion of CO2 to higher alcohols (HAs) and higher hydrocarbons (HCs) has a greater advantage compared to C1 products because of their high energy density and wide range of applications in daily life. Despite the immense potential of these chemicals, not much of scientific research has been focused on the conversion of CO2 to HAs. In the present work, we have introduced the concept of strain in designing the material to enhance the CO(2 )to HA performance. We introduced strain in a traditional iron-based catalyst, Fe2O3, by the introduction of indium (In), which facilitates the selective conversion of CO2 to HA. An optimum strain favored a 36.7\% CO2 conversion with a 42\% HA selectivity, and a record yield of 15.42\%. The strain has been tuned further with the introduction of K as a promoter. The introduced strain upon In substitution and K promotion favored the conversion of CO2, which is mapped by powder X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Further, the change in the mechanism upon In incorporation and K promotion has been probed by in situ diffuse reflectance infrared fourier transform spectroscopy, and it is found that the OCHx intermediate, which produces HAs, is more prominent upon In substitution, which favored the enhancement of HA production compared to that of pristine Fe2O3.

}, keywords = {CO2 to HA, Fischer-Tropsch synthesis (FTS), Phase transformation, reverse water gas shift (RWGS) reaction, strain}, issn = {2155-5435}, doi = {10.1021/acscatal.2c0318311118}, author = {Goud, Devender and Churipard, Sathyapal R. and Bagchi, Debabrata and Singh, Ashutosh Kumar and Riyaz, Mohd and Vinod, C. P. and Peter, Sebastian C.} } @article {48088, title = {Structure-tailored surface oxide on Cu-Ga intermetallics enhances CO2 reduction selectivity to methanol at ultralow potential}, journal = {Advanced Materials}, volume = {34}, year = {2022}, month = {MAY}, pages = {2109426}, type = {Article}, abstract = {

Electrochemical CO2 reduction reaction (eCO(2)RR) is performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9Ga4). Among them, CuGa2 selectively converts CO2 to methanol with remarkable Faradaic efficiency of 77.26\% at an extremely low potential of -0.3 V vs RHE. The high performance of CuGa2 compared to Cu9Ga4 is driven by its unique 2D structure, which retains surface and subsurface oxide species (Ga2O3) even in the reduction atmosphere. The Ga2O3 species is mapped by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) techniques and electrochemical measurements. The eCO(2)RR selectivity to methanol are decreased at higher potential due to the lattice expansion caused by the reduction of the Ga2O3, which is probed by in situ XAFS, quasi in situ powder X-ray diffraction, and ex situ XPS measurements. The mechanism of the formation of methanol is visualized by in situ infrared (IR) spectroscopy and the source of the carbon of methanol at the molecular level is confirmed from the isotope-labeling experiments in presence of (CO2)-C-13. Finally, to minimize the mass transport limitations and improve the overall eCO(2)RR performance, a poly(tetrafluoroethylene)-based gas diffusion electrode is used in the flow cell configuration.

}, keywords = {(2) reduction, CO, Electrochemistry, Methanol}, issn = {0935-9648}, doi = {10.1002/adma.202109426}, author = {Bagchi, Debabrata and Raj, Jithu and Singh, Ashutosh Kumar and Cherevotan, Arjun and Roy, Soumyabrata and Manoj, Kaja Sai and Vinod, C. P. and Peter, Sebastian C.} } @article {48047, title = {Tuning of work function of ZnO by doping and co-doping: an investigation using X-ray photoelectron spectroscopy}, journal = {Thin Solid Films}, volume = {761}, year = {2022}, month = {NOV}, pages = {139538}, type = {Article}, abstract = {

The shift in the work function of the ZnO thin film upon varying codoping ratio has been investigated by X-ray photoelectron spectroscopy. A notable shift of 0.2 eV in the work function was achieved in the films when the Al: In doping ratio was changed from 0:10 to 10:0. The elemental composition of the dopants obtained from XPS analysis showed the presence of more amount of In dopant than Al in codoped ZnO films. In this way a clear understanding of the variation in electrical properties on dopant ratio is obtained. A decrease in work function was also observed with the increase in free carrier concentration when the codopant ratio is changed. The effects of Burstein moss, band narrowing, and band renormalization observed in the bandgap were explained by an upward and downward shift of valence band maxima of the corresponding thin films. The controllable work function of the codoped ZnO films by varying the doping ratio offers excellent potential advantages in optoelectronic devices.

}, keywords = {Indium -Aluminum co -doping, Spray coating, thin film, Work function, X-ray photoelectron spectroscopy, Zinc oxide}, issn = {0040-6090}, doi = {10.1016/j.tsf.2022.139538}, author = {Soumya, K. and Selvam, I. Packia and Vinod, C. P. and Potty, S. N.} } @article {47829, title = {Ultrathin twisty PdNi alloy nanowires as highly active ORR electrocatalysts exhibiting morphology-induced durability over 200 K cycles}, journal = {Nano Letters}, volume = {22}, year = {2022}, month = {JAN}, pages = {246-254}, type = {Article}, abstract = {Even though the anion exchange membrane fuel cells have many advantages, the stability of their electrocatalysts for oxygen reduction reaction (ORR) has remained remarkably poor. We report here on the ultrathin twisty PdNi-alloy nanowires (NWs) exhibiting a very low reaction overpotential with an E1/2 \~{} 0.95 V versus RHE in alkaline media maintained over 200 K cycles, the highest ever recorded for an electrocatalyst. The mass activity of the used NWs is >10 times higher than fresh commercial Pt/C. Therein, Ni improves the Pd d-band center for a more efficient ORR, and its leaching continuously regenerates the surface active sites. The twisty nanowire morphology imparts multiple anchor points on the electrode surface to arrest their detachment or coalescence and extra stability from self-entanglement. The significance of the NW morphology was further confirmed from the high-temperature durability studies. The study demonstrates that tailoring the number of contact points to the electrode-surface may help realize commercial-grade stability in the highly active electrocatalysts.}, doi = {10.1021/acs.nanolett.1c03704}, author = {Sahoo, Lipipuspa and Garg, Reeya and Kaur, Komalpreet and Vinod, C. P. and Gautam, Ujjal K.} } @article {48200, title = {Unravelling faradaic electrochemical efficiencies over Fe/Co spinel metal oxides using surface spectroscopy and microscopy techniques}, journal = {Nanoscale}, volume = {14}, year = {2022}, month = {NOV }, pages = {15928-15941}, type = {Article}, abstract = {

Cobalt and iron metal-based oxide catalysts play a significant role in energy devices. To unravel some interesting parameters, we have synthesized metal oxides of cobalt and iron (i.e. Fe2O3, Co3O4, Co2FeO4 and CoFe2O4), and measured the effect of the valence band structure, morphology, size and defects in the nanoparticles towards the electrocatalytic hydrogen evolution reaction (HER), the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). The compositional variations in the cobalt and iron precursors significantly alter the particle size from 60 to \<10 nm and simultaneously the shape of the particles (cubic and spherical). The Tauc plot obtained from the solution phase ultraviolet (UV) spectra of the nanoparticles showed band gaps of 2.2, 2.3, 2.5 and 2.8 eV for Fe2O3, Co3O4, Co2FeO4 and CoFe2O4, respectively. Further, the valence band structure and work function analysis using ultraviolet photoelectron spectroscopy (UPS) and core level X-ray photoelectron spectroscopy (XPS) analyses provided better structural insight into metal oxide catalysts. In the Co3O4 system, the valence band structure favors the HER and Fe2O3 favors the OER. The composites Co2FeO4 and CoFe2O4 show a significant change in their core level (O 1s, Co 2p and Fe 2p spectra) and valence band structure. Co3O4 shows an overpotential of 370 mV against 416 mV for Fe2O3 at a current density of 2 mA cm(-2) for the HER. Similarly, Fe2O3 shows an overpotential of 410 mV against the 435 mV for Co3O4 at a current density of 10 mA cm(-2) for the OER. However, for the ORR, Co3O4 shows 70 mV improvement in the half-wave potential against Fe2O3. The composites (Co2FeO4 and CoFe2O4) display better performance compared to their respective parent oxide systems (i.e., Co3O4 and Fe2O3, respectively) in terms of the ORR half-wave potential, which can be attributed to the presence of the oxygen vacancies over the surface in these systems. This was further corroborated in density functional theory (DFT) simulations, wherein the oxygen vacancy formation on the surface of CoFe2O4(001) was calculated to be significantly lower (similar to 50 kJ mol(-1)) compared to Co3O4 (001). The band diagram of the nanoparticles constructed from the various spectroscopic measurements with work function and band gap provides in-depth understanding of the electrocatalytic process.

}, issn = {2040-3364}, doi = {10.1039/d2nr04170g}, author = {Kashyap, Varchaswal and Pandikassala, Ajmal and Singla, Gourav and Khan, Tuhin Suvra and Haider, M. Ali and Vinod, C. P. and Kurungot, Sreekumar} } @article {48935, title = {Active site engineering and theoretical aspects of {\textquoteleft}{\textquoteleft}Superhydrophilic{\textquoteright}{\textquoteright} nanostructure array enabling efficient overall water electrolysis}, journal = {Small}, volume = {19}, year = {2023}, month = {DEC}, type = {Article}, abstract = {

The rational design of noble metal-free electrocatalysts holds great promise for cost-effective green hydrogen generation through water electrolysis. In this context, here, the development of a superhydrophilic bifunctional electrocatalyst that facilitates both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline conditions is demonstrated. This is achieved through the in situ growth of hierarchical NiMoO4@CoMoO4 center dot xH(2)O nanostructure on nickel foam (NF) via a two-step hydrothermal synthesis method. NiMoO4@CoMoO4 center dot xH(2)O/NF facilitates OER and HER at the overpotentials of 180 and 220 mV, respectively, at the current density of 10 mA cm(-2). The NiMoO4@CoMoO4 center dot xH(2)O/NF parallel to NiMoO4@CoMoO4 center dot xH(2)O/NF cell can be operated at a potential of 1.60 V compared to 1.63 V displayed by the system based on the Pt/C@NF parallel to RuO2@NF standard electrode pair configuration at 10 mA cm(-2) for overall water splitting. The density functional theory calculations for the OER process elucidate that the lowest Delta G of NiMoO4@CoMoO4 compared to both Ni and NiMoO4 is due to the presence of Co in the OER catalytic site and its synergistic interaction with NiMoO4. The preparative strategy and mechanistic understanding make the windows open for the large-scale production of the robust and less expensive electrode material for the overall water electrolysis.

}, keywords = {density functional theory (DFT) study, hydrogen evolution reaction (HER), Hydrothermal synthesis, oxygen evolution reaction (OER), superhydrophilic nanostructures, synergistic interaction, water electrolysis}, issn = {1613-6810}, doi = {10.1002/smll.202304143}, author = {Barik, Sidharth and Kharabe, Geeta Pandurang and Illathvalappil, Rajith and Singh, Chandrodai Pratap and Kanheerampockil, Fayis and Walko, Priyanka S. and Bhat, Suresh K. and Devi, R. Nandini and Vinod, C. P. and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {48261, title = {Covalently interconnected layers in g-C3N4: toward high mechanical stability, catalytic efficiency and sustainability}, journal = {Applied Catalysis B: Environmental}, volume = {322}, year = {2023}, month = {MAR}, pages = {122069}, type = {Article}, abstract = {

The grim prospects for the industrial utilization of g-C3N4 nanosheets arise from multi-step processing resulting in low material yields and poor visible light response due to quantum confinement. Herein, we introduce a strategy for linking the adjacent layers of g-C3N4 covalently to realize a high surface area without excess mass loss in a one-step process by introducing diethylene glycol as a precursor that produces-(CH2)2-O-(CH2)2-linkers in-situ. Their presence increases interlayer spacing and introduces surface curvatures, discouraging the stacking of a larger number of layers to produce nanosheets with-3 times higher surface area. Interestingly, unlike other layered materials, the linkers also provide extraordinary mechanical stability against exfoliating forces. In addition, the process instills sub-bandgap states and a considerable visible light response at 500 nm to slow down the picosecond exciton recombination dynamics, resulting in-5 times enhancement in H2 generation efficiency from photocatalytic water-splitting over the bulk sample.

}, keywords = {Layer-linkers, Sustainable synthesis, Transient absorption spectroscopy, water-splitting}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2022.122069}, author = {Roy, Raj Sekhar and Mondal, Sanjit and Mishra, Samita and Banoo, Maqsuma and Sahoo, Lipipuspa and Kumar, Amit and Vinod, C. P. and De, Arijit K. and Gautam, Ujjal K.} } @article {48271, title = {Hydrogenation of levulinic acid to gamma-valerolactone over nickel supported organoclay catalyst}, journal = {Catalysis Today}, volume = {408}, year = {2023}, month = {JAN }, pages = {36-49}, type = {Article}, abstract = {

In this work, a series of Ni/Organoclay catalysts with different Nickel loadings were prepared by the wetimpregnation method for the catalytic hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL). Reaction parameters such as reaction temperature, pressure, solvent effect, and wt\% of catalyst were optimized to get excellent conversion of levulinic acid selectively to gamma-valerolactone. Ni/Organoclay with 30\% Nickel loading exhibited 100\% conversion of LA with 100\% selectivity towards GVL at 140 degrees C and 3.0 MPa H2 pressure using 1,4-dioxane as a solvent in 5 h. Different bulk and surface characterization techniques such as XRD, BET, FE-SEM, HR-TEM, XPS, XRF, NH3-TPD, and H2-Chemisorption were used to characterize the Ni/Organoclay catalyst. BET and NH3-TPD analysis showed that the pre-treatment of bentonite with surfactant (CTAB) improved the pore volume, surface area, and acidity of Organoclay which assisted in improving the conversion and selectivity of LA and GVL respectively.

}, keywords = {?-Valerolactone (GVL), Bentonite, Hydrogenation, Levulinic acid (LA), Nickel, organoclay}, issn = {0920-5861}, doi = {10.1016/j.cattod.2022.10.004}, author = {Kamble, Paresh A. and Vinod, C. P. and Rathod, Virendra K. and Kantam, Mannepalli Lakshmi} } @article {48458, title = {Imine oxidation catalyzed by zinc hydroxyapatite: kinetic studies}, journal = {ChemistrySelect}, volume = {8}, year = {2023}, month = {MAY}, pages = {e202203503}, type = {Article}, abstract = {

The synthesis of N,N-diphenylformamide from N-benzylideneaniline and urea hydrogen peroxide is investigated using a zinc hydroxyapatite (ZnHAP) catalyst. It was found that the catalyst resulted in the highest activity of 91 \% conversion and 40 \% selectivity at 130 degrees C in 2 h. A kinetic model was validated by Langmuir-Hinshelwood-Hougen-Watson (LHHW) at different temperatures and the absence of mass transfer resistance was proved by the Weisz Prater criterion. Effect of different catalysts, catalyst loading, temperature, mole-ratio, and speed of stirring was studied. The as-synthesized catalyst is characterized by FTIR, BET nitrogen adsorption-desorption, TEM, EDX, TPD-NH3, XPS, ICP-MS and XRD. ZnHAP catalyst was found to be stable up to three recycles with no loss in activity.

}, keywords = {heterogeneous catalysis, hydroxyapatite, imines, Oxidation, Reaction kinetics}, issn = {2365-6549}, doi = {10.1002/slct.202203503}, author = {Vishwakarma, Rakhi and Vinod, C. P. and Rathod, Virendra K. and Kantam, Mannepalli Lakshmi} } @article {48820, title = {Metal deficiency tailored by the 18-electron rule stabilizes metal-based inorganic compounds}, journal = {Chemistry of Materials}, volume = {35}, year = {2023}, month = {JUL}, pages = {6050-6058}, type = {Article}, abstract = {

The 18-electron (18-e(-)) rule is typicallyrestrictedto predicting the stability of transition-metal-based complexes. Herein,we report the use of the 18-e(-) to predict the stabilityin a family of intermetallics MNiSn (M = V, Cr, Fe, and Co) crystallizingin the Co1.75Ge structure type. Site deficiencies at theM site obtained from single-crystal X-ray diffraction are understoodas attaining a stable noble gas electronic configuration. The densityfunctional theory -based structure calculation confirms that the deficientstructure is more stable than the ideal occupation available at thecrystal lattice. MnNiSn, which crystallizes in the half-Heusler crystalstructure, depicts the role of covalent radii of the constituent elementsin determining the crystal structure. Using X-ray absorption spectroscopyand X-ray photoelectron spectroscopy, the local structure of the above-mentionedcompounds was also elucidated, supporting the role of deficiency tunedvalence fluctuation to attain a 18-e(-) configurationthat eventually leads to the formation of stable compounds.

}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.3c01142}, author = {Singh, Ashutosh Kumar and Mumbaraddi, Dundappa and Mishra, Vidyanshu and Roy, Soumyabrata and Vinod, C. P. and Peter, Sebastian C.} } @article {48778, title = {Morphology-dependent catalysis by Co3O4 nanostructures in atmospheric pressure carbon dioxide hydrogenation}, journal = {Journal of Physical Chemistry C}, volume = {127}, year = {2023}, month = {JUL}, pages = {13055-13064}, type = {Article}, abstract = {

In this work, three Co3O4 nanostructureswith different morphologies (cubes, rods, and sheets) were synthesizedusing a hydrothermal method and tested for the CO2 hydrogenationreaction. The physicochemical properties of the structured Co3O4 were well characterized by X-ray diffraction(XRD), Raman spectroscopy, field-emission scanning electron microscopy(FESEM), transmission electron microscopy (TEM), high-resolution transmissionelectron microscopy (HRTEM), hydrogen temperature-programmed reduction(H-2-TPR), and X-ray photoelectron spectroscopy (XPS) techniques.Based on the characterization, cube, rod, and sheet Co3O4 nanostructures were found to expose the (100), (110),and (112) planes, respectively. The effect of cobalt oxide morphologieswith different exposed surfaces on the activity and selectivity towardCO(2) hydrogenation reaction in a plug-flow reactor operatedbetween 200 and 400 \& DEG;C under atmospheric pressure conditionswas explored. The results establish a correlation of the catalyticactivity with morphological structures in the order rods \> sheets\> cubes. H-2-TPR and XPS studies demonstrated that thehighreducibility of Co3O4 rod makes it an excellentcatalyst for CO2 hydrogenation.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.3c02857}, author = {Gupta, Sharad and Jain, Preeti and Jagadeesan, Dinesh and Vinod, C. P.} } @article {48292, title = {Oxidation of ethylene by Cu/TiO2: reducibility of Cu2+ in TiO2 as a possible descriptor of catalytic efficiency}, journal = {Catalysis Science \& Technology}, volume = {13}, year = {2023}, month = {APR}, pages = {2330-2339}, type = {Article}, abstract = {

Catalytic oxidation using non-noble metal-based catalysts is a promising approach to mitigate pollution due to VOCs in the air. In this work, mesoporous Cu/TiO2 catalysts containing different concentrations of Cu2+ (0.2, 1, 3, and 4 wt\% Cu w.r.t. Ti) were synthesized using the sol-gel technique. The catalysts were characterized using inductively coupled plasma-optical emission spectrometry, XRD, Raman spectroscopy, N-2 physisorption, cyclic voltammetry, H-2-TPR and electron microscopy to understand the structure and composition. The thermal catalytic gas phase oxidation of ethylene was studied by heating a mixture of ethylene (1.5 vol\%) and air (5.9 vol\%) in the presence of the Cu/TiO2 samples in the temperature range of 298 to 773 K. Cu/TiO2 showed a higher catalytic activity compared to TiO2 for the thermal oxidation of ethylene, indicating a strong promotion by doped copper ions. A volcanic behaviour in the catalytic activity was observed with different concentrations of Cu doping, with 1\% Cu/TiO2 showing a 99.5\% ethylene conversion at 673 K and 100\% selectivity to CO2. The activity of 1\% Cu/TiO2 remained consistent without deactivation for 24 h. At low dopant concentrations of Cu (0.2 and 1\% Cu/TiO2), the reduction of Cu2+ to Cu+ was observed. An interplay of oxygen vacancies (O-V), Cu+, Cu2+ and Ti4+ may be involved in controlling the activity. DRIFT studies indicated the formation of surface bidendate carbonate as a possible intermediate.

}, issn = {2044-4753}, doi = {10.1039/d2cy02170f}, author = {Rajendran, K. and Sharma, Mandeep and Jaison, Augustine and Ankitha, Menon and Tiwari, Ankit D. and Vinod, C. P. and Jagadeesan, Dinesh} } @article {48723, title = {Pd nanoparticles supported on N-incorporated hybrid organosilica as an active and selective low-temperature phenol hydrogenation catalyst}, journal = {ACS Applied Nano Materials}, volume = {6}, year = {2023}, month = {JUN}, pages = {11500-11512}, type = {Article}, abstract = {

A heterogeneous Pd-NPMO hybrid-silicacatalyst is synthesized andits application for aqueous phase selective hydrogenation of phenolto cyclohexanone at near ambient temperature (40 degrees C) and underatmospheric hydrogen pressure is demonstrated. The homogeneously distributedPd nanoparticles on N-bridged hybrid mesoporous organosilica showedremarkable activity and selectivity for cyclohexanone compared tothe unmodified Pd-SBA-15 catalyst. Control experiments strongly claimthe role of nitrogen domains in the organic framework of hybrid silicasupport in stabilizing small Pd nanoparticles and possibly modifyingthe Pd sites responsible for catalysis to activate the substrate moleculesin water. The hybrid silica catalyst was stable and reused severaltimes without any significant drop-in activity, proving the heterogeneityof the bifunctional Pd catalyst. Based on the density functional theorystudy and experimental interventions, a possible reaction mechanismfor the low-temperature phenol hydrogenation explaining the role oforganic domains in the hybrid-silica framework is proposed.

}, keywords = {cyclohexanone, Hybrid silica, palladium nanoparticles, Periodic mesoporous organosilica, phenol hydrogenation}, doi = {10.1021/acsanm.3c01540}, author = {Betsy, K. J. and Bajpai, Priyam and Lazar, Anish and Vanka, Kumar and Vinod, C. P.} } @article {49391, title = {Atmospheric-pressure continuous-flow methane oxidation to methanol and acetic acid using H2O2 over the Au-Fe catalyst}, journal = {ACS SUSTAINABLE CHEMISTRY \& ENGINEERING}, volume = {12}, year = {2024}, month = {MAY }, pages = {8958-8967}, type = {Journal Article}, keywords = {CO oxidation, HIGHLY SELECTIVE OXIDATION, metal-organic frameworks}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.4c02993}, author = {Jagtap, Anuradha V. and Kumar, Pawan and Gupta, Sharad and Nagendra, Abharana and Jha, Shambhu Nath and Bhattacharyya, D. and Ajithkumar, Thalasseril G. and Vinod, C. P.} } @article {49360, title = {Breaking the Pt electron symmetry and OH spillover towards ptir active center for performance modulation in direct ammonia fuel cell}, journal = {Small}, volume = {20}, year = {2024}, month = {DEC}, type = {Article}, abstract = {

The growing interest in low-temperature direct ammonia fuel cells (DAFCs) arises from the utilization of a carbon-neutral ammonia source; however, DAFCs encounter significant electrode overpotentials due to the substantial energy barrier of the *NH2 to *NH dehydrogenation, compounded by the facile deactivation by *N on the Pt surface. In this work, a unique catalyst, Pt4Ir@AlOOH/NGr i.e., Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles controllably decorated on the pseudo-boehmite phase of AlOOH-supported nitrogen-doped reduced graphene (AlOOH/NGr) composite, synthesized via the polyol reduction method. The detailed studies on the structural and electronic properties of the catalyst by XAS and VB-XPS reveal the possible electronic modulations. The optimized Pt4Ir/ANGr composition exhibits a significantly improved onset potential and mass activity for AOR. The DFT study confirms the OHad species spillover by AlOOH and Pt4Ir (100) facilitates the conversion of the *NH2 to *NH with minimal energy barriers. Finally, testing of DAFC at the system level using a membrane electrode assembly (MEA) with Pt4Ir/ANGr as the anode catalyst, demonstrating the suitability of the catalyst for its practical applications. This study thus uncovers the potential of the Pt4Ir catalyst in synergy with ANGr, largely addressing the challenges in hydrogen transportation, storage, and safety within DAFCs. In this article, a versatile catalyst, Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles decorated on AlOOH/NGr composite. The AlOOH provides an -OH-rich surface conducive to the facile adsorption and decoration of the PtIr alloy nanoparticles and OHad species spillover from AlOOH to the Pt4Ir active center during AOR, further validating the higher experimental activity obtained in Pt4Ir/ANGr. image

}, keywords = {ammonia oxidation reaction (AOR), d-band center, density functional theory (DFT) study, direct ammonia fuel cells, hydroxyl spillover effect, XAS analysis}, issn = {1613-6810}, doi = {10.1002/smll.202406589}, author = {Barik, Sidharth and Kharabe, Geeta Pandurang and Samal, Pragnya Paramita and Urkude, Rajashri R. and Kumar, Sachin and Yoyakki, Athira and Vinod, C. P. and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {49282, title = {Exploring the CeO2 support morphology for the carbon dioxide hydrogenation reaction using nickel catalysts}, journal = {Journal of Physical Chemistry C}, volume = {128}, year = {2024}, month = {OCT}, pages = {18782-18792}, type = {Article}, abstract = {

The catalytic activity and stability are examined for the hydrogenation of carbon dioxide under atmospheric pressure over 2 wt \% Ni/CeO2 nanorods (2Ni-CeNRs), nanocubes (2Ni-CeNCs), and nanopolyhedra (2Ni-CeNPs). The 2Ni-CeNR catalysts display excellent catalytic activity and higher stability compared with 2Ni-CeNC and 2Ni-CeNP catalysts. A comprehensive understanding of the surface atomic and electronic structure versus activity has been derived using high-resolution electron microscopy and spectroscopy techniques. High metal dispersion, strong metal-support interaction (SMSI) effect and abundant oxygen vacancies are deduced to play a crucial role in determining the catalytic activity and selectivity of the CO2 hydrogenation reaction.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.4c05258}, author = {Gupta, Sharad and Jagtap, Anuradha and Vinod, C. P.} } @article {49113, title = {Facile synthesis of nanostructured Ni/NiO/N-doped graphene electrocatalysts for enhanced oxygen evolution reaction}, journal = {Nanoscale Advances}, volume = {6}, year = {2024}, month = {MAY}, pages = {2813-2822}, type = {Article}, abstract = {

Electrocatalysts containing a Ni/NiO/N-doped graphene interface have been synthesised using the ligand-assisted chemical vapor deposition technique. NiO nanoparticles were used as the substrate to grow N-doped graphene by decomposing vapours of benzene and N-containing ligands. The method was demonstrated with two nitrogen-containing ligands, namely dipyrazino[2,3-f:2 {\textquoteleft},3 {\textquoteleft}-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (L) and melamine (M). The structure and composition of the as-synthesized composites were characterized by XRD, Raman spectroscopy, SEM, TEM and XPS. The composite prepared using the ligand L had NiO sandwiched between Ni and N-doped graphene and showed an overpotential of 292 mV at 10 mA cm-2 and a Tafel slope of 45.41 mV dec-1 for the OER, which is comparable to the existing noble metal catalysts. The composite prepared using the ligand M had Ni encapsulated by N-doped graphene without NiO. It showed an overpotential of 390 mV at 10 mA cm-2 and a Tafel slope of 78.9 mV dec-1. The ligand-assisted CVD route demonstrates a facile route to control the microstructure of the electrocatalysts. Electrocatalysts containing a Ni/NiO/N-doped graphene interface have been synthesised using the ligand-assisted chemical vapor deposition technique.

}, issn = {2516-0230}, doi = {10.1039/d4na00141a}, author = {Madampadi, Roshni and Patel, Avit Bhogilal and Vinod, C. P. and Gupta, Ritu and Jagadeesan, Dinesh} } @article {49084, title = {Hydrogenation of furfural to tetrahydrofurfuryl alcohol over nickel-supported on organoclay catalyst}, journal = {Applied Catalysis A-General}, volume = {674}, year = {2024}, month = {MAR }, pages = {119621}, type = {Article}, abstract = {

Nickel supported on organoclay prepared by the impregnation method provides excellent catalytic activity for the hydrogenation of furfural to tetrahydrofurfuryl alcohol. The relative amount of metal and acidic sites influences the hydrogenation reaction. Additionally, by varying the temperature and the H-2 pressure, we can regulate the interaction of furfural with the active sites. And this may decide the fate of the reaction whether it will undergo a two-step hydrogenation to form tetrahydrofurfuryl alcohol or a rearrangement reaction to form cyclopentanone/cyclopentanol. Water was found to be the best solvent for the selective formation of tetrahydrofurfuryl alcohol. Even though alcohols inhibited rearrangement reaction, the hydrogenation of furfural was more selective towards furfuryl alcohol. Ni/O-clay30A under the optimum conditions of 120 degrees C, 4.0 MPa, and in 1 h offered complete conversion of furfural to tetrahydrofurfuryl alcohol.

}, keywords = {furfural, Hydrogenation, Nickel, organoclay, Tetrahydrofurfuryl alcohol}, issn = {0926-860X}, doi = {10.1016/j.apcata.2024.119621}, author = {Kamble, Paresh A. and Vinod, C. P. and Rathod, Virendra K. and Kantam, Mannepalli Lakshmi} } @article {49017, title = {Iron-catalyzed (E)-selective hydrosilylation of alkynes: scope and mechanistic insights}, journal = {Catalysis Science and Technology}, volume = {14}, year = {2024}, month = {MAY}, type = {Article}, abstract = {

Iron-catalyzed hydrosilylation of internal alkynes has been rarely reported. Even in these rare cases, additives have been used for the success of the reaction, which often creates a problem for the functional group tolerance of the reaction. Herein, we report an additive-free iron-catalyzed (E)-selective hydrosilylation of internal alkynes in the presence of a phosphine ligand. A low-valent Fe(0) complex [Fe(CO)(3)(BDA)] {[Fe-1]} catalyzed the hydrosilylation of alkynes at 60 to 120 degrees C, exhibited a broad substrate (24 substrates) scope and tolerated different functional groups. The synthetic utility of the reaction was demonstrated by a gram scale experiment, preparing alkenes, and by chemo-selective hydrosilylation. The modus operandi of the reaction has been investigated by i) homogeneity test, ii) radical trapping experiments, iii) X-ray photoelectron spectroscopy, and iv) by preparing a Fe(II) complex as catalyst control. These mechanistic investigations revealed a two-electron pathway for the hydrosilylation of alkynes. In addition, kinetic investigations were undertaken to shed light on the rates of the reaction. Kinetic studies suggest the absence of an induction period, and the reaction is first order with respect to the concentration of iron catalyst [Fe-1] and zeroth order with respect to the substrate (alkyne). The Hammett plot suggests that strongly electron-withdrawing groups on the alkyne favour the hydrosilylation reaction. Meanwhile Eyring analysis suggests that the rate-determining step likely involves an associative pathway. Based on the findings of the mechanistic and kinetic investigation, a plausible Chalk-Harrod-type mechanism is likely to be operative. The proposed mechanism is substantiated by computational investigations, which suggested that the Chalk-Harrod mechanism is kinetically more favored by 15.8 kcal mol(-1) over the modified Chalk-Harrod mechanism.

}, issn = {2044-4753}, doi = {10.1039/d3cy01775c}, author = {Sen, Anirban and Tewari, Tanuja and Kumar, Rohit and Vinod, C. P. and Sharma, Himanshu and Vanka, Kumar and Chikkali, Samir H.} } @article {49420, title = {Enhanced light-matter interaction in gas nitridation-derived TiNx thin films for potential plasmonic applications}, journal = {Journal of Materials Science}, volume = {60}, year = {2025}, month = {JAN}, pages = {178-194}, type = {Article}, abstract = {

Titanium nitride is a substitute material exhibiting improved opto-electrical characteristics suitable for plasmonic purposes with adjustable attributes. In this study, we have embraced an innovative methodology for the fabrication of titanium nitride thin coatings via the nitridation of RF magnetron-sputtered titanium metallic films for surface plasmon resonance utilisation. The augmented electrical and optical features of TiN thin coatings prepared through the nitridation procedure are reported for the first time. The metallic coatings underwent gas nitridation at diverse temperatures within the range of 450-600 degrees C. The titanium nitride phase evolution in the coatings was corroborated by x-ray diffraction and x-ray photoelectron spectroscopy examinations. The dielectric function is deduced from reflection spectra through Drude-Lorentz model fitting, and the manifestation of surface plasmon excitation in the visible region was confirmed by correlating with carrier concentration assessments and by ensuring the required negative permittivity in the region. The red shift of screened plasma wavelength was observed with the nitridation temperature, and the same is varied in the wavelength range 400-700 nm. Ultimately, surface plasmons were excited in coatings with optimised thickness using Kretschmann configuration in wavelength interrogation mode.

}, issn = {0022-2461}, doi = {10.1007/s10853-024-10520-y}, author = {Tony, Liya and Selvam, I. Packia and Vinod, C. P. and Potty, S. N.} } @article {49729, title = {Facet dependence for solvent-modulated proton-coupled electron transfer in furfural acetalization on Pd nanostructures}, journal = {Chemical Engineering Journal}, volume = {514}, year = {2025}, month = {JUN}, pages = {163159}, type = {Article}, abstract = {

Furfural dialkyl acetals prepared via acetalization reaction of furfural and alcohols are promising biofuels. Using defined experiments and density functional theory (DFT) simulations, the structure-dependent activity and selectivity for furfural acetalization reaction in the presence of alcohols (methanol, ethanol, propanol and butanol) as solvents was studied over well-defined supported Pd nanostructures (octahedra (111), cubes (100) and spheres (both (111) and (100)). Pd cubes supported over TiO2 in the presence of ethanol as a solvent (at 303 K and balloon pressure H-2) exhibited 78 \% conversion and 100 \% selectivity for furfural diethyl acetal product in a short time (similar to 180 min). In contrast, Pd octahedra (111) and Pd spheres showed low conversions (18 \% and 6 \%) at the same reaction conditions. Interestingly, when used as a solvent, methanol showed the highest conversion (90 \%) and selectivity (100 \%) for furfural acetalization over Pd cubes. DFT simulations provided mechanistic insight into the reactivity of the two different Pd facets (111) and (100) in the presence of alcohol molecules towards furfural acetalization reaction. A three-step reaction mechanism was proposed for furfural acetalization with alcohols: (i) alcohol hydroxyl-dehydrogenation (ii) hydrogenation of furfural carbonyl oxygen, and (iii) formation of hemiacetal product. For all three steps, Pd (100) exhibited low activation barriers (51.6, 26.7 and 76.2 kJ/mol) compared to Pd (111) surface (78.6, 35.8 and 92.2 kJ/mol) in the presence of ethanol. The activation barriers for the above steps were further reduced to 47.8, 23.9 and 64.6 kJ/mol on Pd (100) in the presence of methanol, explaining the experimental high reactivity aided by methanol. DFT calculations elucidated the role of the hydrogen bonding network between the solvent molecules and adsorbate, enabling proton-coupled electron transfer for accelerated reactions.

}, keywords = {Acetalization, DFT, facet-dependent reactivity, furfural, Furfural dialkyl acetals, solvent effect}, issn = {1385-8947}, doi = {10.1016/j.cej.2025.163159}, author = {Porwal, Govind and Dandekar, Pallavi and Gorai, Twinkle and Khan, Tuhin Suvra and Haider, M. Ali and Gupta, Shelaka and Vinod, C. P.} } @article {49596, title = {Hot injection assisted electronically modulated twin and grain boundary rich sub-2 nm pt3co alloy resistant to phosphate ion for PEMFCs}, journal = {Small}, volume = {21}, year = {2025}, month = {MAY}, type = {Article}, abstract = {

Modulation of the electronic d-band center, structural defects (line defects), and particle size of Pt3Co alloy electrocatalyst have huge significance in elevating its electrochemical oxygen reduction reaction activity. Deviating from traditional high-temperature strategies, the current work focuses on ripening these benefits by implying a simple economically viable hot-injection-assisted modified polyol process. A conclusive control over decrementing particle size starting from 2.7 to 1.3 nm, an increasing degree of strain (twin boundary), and shifting of the d-band center away from the Fermi level are obtained via varying the temperature to which the solution is injected. The catalyst prepared via the injection at 200 degrees C (Pt3Co(1.3 t,g-b)/fVC-200) has delivered an electrochemical surface area of 84 m(2) g(Pt)(-1) with the onset and half-wave potentials of 0.980 and 0.858 V, respectively, versus RHE and a limiting current of -6.0 mA cm(-2) with stability till 20k cycles. In the high-temperature proton exchange membrane fuel cell Pt3Co(1.3 t,g-b)/fVC-200-based cell has outperformed Pt/C rendering 600 mWcm(-2) under H-2-Air compared to 529 mWcm(-2) of Pt/C with 20\% lower Pt loading and double the stability due to enhanced resistance toward phosphoric acid for accelerated voltage cycling. A similar enhancement is seen while employing the catalyst for low-temperature fuel cells.

}, keywords = {electrocatalyst, grain boundary, hot injection synthesis, modified polyol process, oxygen reduction reaction, proton exchange membrane fuel cell, Pt3Co alloy, twin boundary, valance band X-ray photoelectron spectroscopy}, issn = {1613-6810}, doi = {10.1002/smll.202500954}, author = {Singh, Mayank U. and Jadhav, Swapnil D. and Shivankar, Bhavana R. and Pandikassala, Ajmal and Kumar, Yogesh and Krishnamurty, Sailaja and Vinod, C. P. and Kurungot, Sreekumar} } @article {49721, title = {Hydrogenation of CO2 catalyzed by thermally decomposed cobalt-containing alkaline earth metal carbonates}, journal = {Energy \& Fuels}, volume = {39}, year = {2025}, month = {JUN}, pages = {12982-12991}, type = {Article}, abstract = {

CO2 hydrogenation over Co catalysts supported on alkaline earth metal oxides was investigated. The catalysts were prepared by thermally decomposing alkaline metal carbonates CoMCO3, where M = Mg, Ca, Sr, and Ba, in H2. During the thermal activation, contingent upon the thermal stability of the precursor, it transformed into a composite of metal oxides, metals, and undecomposed metal carbonates. The thermal activation temperature, the ratio of CO2 to H2, the composition, and the basicity of the catalyst all played a significant role in influencing the conversion of CO2 and the selectivity to CH4. Among the various Co-containing alkaline earth metal carbonate precursors, CoCaCO3 activated at 400 degrees C yielded the highest steady-state CO2 conversion of 54\% with a CH4 selectivity of 89.8\% throughout 28 h in the reaction stream containing a 1:4 ratio of CO2 and H2. Detailed characterization showed that the CaCo-400 catalyst contained metallic Co, CaO, and undecomposed CaCO3 phases. The study assumes significance in understanding the role of the composition of catalysts in the formation of CO2 hydrogenation.

}, issn = {0887-0624}, doi = {10.1021/acs.energyfuels.5c01793}, author = {Gupta, Sharad and Vinod, C. P. and Poupin, Christophe and Jagadeesan, Dinesh} } @article {49565, title = {Unravelling the Cu-Co nanoparticle synergy over Ceria-Zirconia support toward efficient reverse water gas shift (RWGS) conversion under H2 lean conditions}, journal = {Chemical Engineering Journal}, volume = {508}, year = {2025}, month = {MAR}, pages = {160705}, type = {Article}, abstract = {

CO2 emissions leading to global warming and environmental and socio-economic issues have propelled the research community to develop technologies capable of capturing and converting CO2 into valuable products. Controlling the selectivity toward platform molecules like CO, methanol, or methane is a fundamental challenge in CO2 hydrogenation. Supported cobalt nanoparticles are known for hydrocarbon production through FischerTropsch (FT) reaction, and Cu-based catalysts are known for reverse water gas shift (RWGS) reaction. Here, we show that d-band centre can be carefully modulated by making bimetallic combinations of Cu and Co for a highly active RWGS catalyst. An oxygen vacancy-rich nanostructured ceria-zirconia (CZ) support with Cu nanoparticles (2 wt\%) modified with as low as 0.05 wt\% Co shows excellent conversion for CO2 hydrogenation and selectivity for CO below 500 degrees C. The optimized catalyst shows CO2 conversion even under hydrogen lean conditions (H2/ CO2 ratio 0.5:1), with a breakthrough rate of 206023 mmol/gmetal/h for CO at 600 degrees C, having H2 utilization of 80\% for the RWGS process.

}, keywords = {Bimetallic catalyst, Ceria-zirconia, CO 2 hydrogenation, Cobalt catalyst, Copper catalyst, Reverse water gas shift (RWGS), synergistic effect}, issn = {1385-8947}, doi = {10.1016/j.cej.2025.160705}, author = {Jagtap, Anuradha Vijay and Bamnia, Mahesh Kumar and Maibam, Ashakiran and Bajpai, Jyotsna Paliwal and Gupta, Sharad and Thomas, Sharon K. and Dabke, Niteen B. and Vinod, C. P.} }