@article {47068, title = {Operando generated ordered heterogeneous catalyst for the selective conversion of CO2 to methanol}, journal = {ACS Energy Letters}, volume = {6}, year = {2021}, month = {FEB }, pages = {509-516}, type = {Article}, abstract = {

The discovery of new materials for efficient transformation of carbon dioxide (CO2) into desired fuel can revolutionize large-scale renewable energy storage and mitigate environmental damage due to carbon emissions. In this work, we discovered an operando generated stable Ni-In kinetic phase that selectively converts CO2 to methanol (CTM) at low pressure compared to the state-of-the-art materials. The catalytic nature of a well-known methanation catalyst, nickel, has been tuned with the introduction of inactive indium, which enhances the CTM process. The remarkable change in the mechanistic pathways toward methanol production has been mapped by operando diffuse reflectance infrared Fourier transform spectroscopy analysis, corroborated by first-principles calculations. The ordered arrangement and pronounced electronegativity difference between metals are attributed to the complete shift in mechanism. The approach and findings of this work provide a unique advance toward the next-generation catalyst discovery for going beyond the state-of-the-art in CO2 reduction technologies.

}, issn = {2380-8195}, doi = {10.1021/acsenergylett.0c02614}, author = {Cherevotan, Arjun and Raj, Jithu and Dheer, Lakshay and Roy, Soumyabrata and Sarkar, Shreya and Das, Risov and Vinod, Chathakudath P. and Xu, Shaojun and Wells, Peter and Waghmare, V, Umesh and Peter, Sebastian C.} } @article {48188, title = {Influence of support textural property on CO2 to methane activity of Ni/ SiO2 catalysts}, journal = {Applied Catalysis B-Environmental}, volume = {317}, year = {2022}, month = {NOV}, pages = {121692}, type = {Article}, abstract = {

In this work, we elucidated the role of physicochemical textural properties of inert support on the catalyst ac-tivity by impregnating Ni on ordered mesoporous silica (SBA-15 and MCM-41) and non-mesoporous silica (nMPS). The catalyst Ni/SBA-15 exhibited the best CO2 conversion (83\%) and product selectivity (99.9 \%) followed by Ni/MCM-41 and the least by Ni/nMPS. The difference in the nature of the catalyst, degree of nanoparticle distribution and nanoparticle encapsulation by different silica support were studied by N2 adsorption-desorption and X-ray photoelectron spectroscopy (XPS) experiments. The Operando Diffused Reflec-tance Infrared Fourier Transform Spectroscopy were used to understand the variance in reaction pathway which is accredited to the textural properties of the support. The SBA-15 supported Ni catalyst followed dissociative CO pathway while MCM-41 and nMPS reacted through associative formate mechanism as major pathway. These findings provide a novel perspective on CO2 hydrogenation over Ni-silica, allowing us to tune both activity and selectivity.

}, keywords = {CO2 methanation, DRIFTS, Mesoporous silica support, Textural properties}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2022.121692}, author = {Cherevotan, Arjun and Ray, Bitan and Churipard, Sathyapal R. and Kaur, Komalpreet and Gautam, Ujjal K. and Vinod, Chathakudath P. and Peter, Sebastian C.} } @article {48415, title = {Noble-metal-free heterojunction photocatalyst for selective CO2 reduction to methane upon induced strain relaxation}, journal = {ACS Catalysis}, volume = {12}, year = {2022}, month = {JAN }, pages = {687-697}, type = {Article}, abstract = {

Sunlight-driven CO2 hydrogenation has drawn tremendous attention. However, selective CH4 formation via CO2 photoreduction is very challenging. Herein, we report a metal oxide semiconductor heterojunction consisting of BiVO4 and WO3 as a photocatalyst for the efficient conversion of carbon dioxide (CO2) selectively to methane (105 mu mol g(-1) h(-1)) under visible light in the absence of a sacrificial agent. Wise selection of the reaction medium and the strategically tuned heterojunction upon strain relaxation suppresses the competitive hydrogen generation reaction. The detailed photophysical, photoelectrochemical, and X-ray absorption spectroscopy studies pointed to the Z-scheme mechanism of electron transfer, which favors superior electron and hole separation compared to the individual components of the composite catalyst and other well-known photocatalysts reported for CO2 reduction. The observations are further corroborated by experimental diffuse reflectance infrared Fourier transform spectroscopy and theoretical density-functional theory calculations, which reveal that the heterojunction has a lower free-energy barrier for CO2 conversion to CH4 due to the larger stabilization of the *CH2O intermediate on the strain-relaxed heterojunction surface, in comparison to the pristine BiVO4 surface. The present work provides fundamental insights for constructing high-performance heterojunction photocatalysts for the selective conversion of CO2 to desired chemicals and fuels.

}, keywords = {CO2 reduction, heterostructure, methane, Photocatalysis, Z-scheme}, issn = {2155-5435}, doi = {10.1021/acscatal.1c04587}, author = {Das, Risov and Sarkar, Shreya and Kumar, Ritesh and Ramarao, Seethiraju D. and Cherevotan, Arjun and Jasil, Mohammed and Vinod, Chathakudath P. and Singh, Abhishek Kumar 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 {48181, title = {Tuning the hybridization and charge polarization in metal nanoparticles dispersed over Schiff base functionalized SBA-15 enhances CO2 capture and conversion to formic acid}, journal = {Journal of Materials Chemistry A}, volume = {10}, year = {2022}, month = {SEP}, pages = {18354-18362}, type = {Article}, abstract = {

Different Schiff base functionalized SBA-15 materials were synthesized through condensation reactions between 3-aminopropyltriethoxysilane (APTES) and different aldehydes (glutaraldehyde and butyraldehyde) over a mesoporous silica, SBA-15 (APTES-GLU/SBA-15 and APTES-BUT/SBA-15). Both static and dynamic experiments have been used for testing the CO2 capture efficiency of these materials. The hybridization of the N atom in APTES has been tuned from sp(3) to sp(2) upon condensation facilitating optimum CO2 capture in the direct synthesis of APTES-GLU/SBA-15. The undesirable oxides of nitrogen have been removed during the synthesis process to improve the CO2 capture efficiency. These materials were employed as supports for Pd-Ag and Pd-Ni bimetallic systems for the selective conversion of the captured CO2 to formic acid (FA) in 0.5 M KHCO3 solution. The Pd-Ni catalyst system exhibited enhanced CO2 to FA conversion activity compared to other heterogeneous systems, which is similar to 4 times better than that of the Pd-Ag system in this study. The X-ray absorption studies over the catalyst material confirmed that the relatively electron-deficient Ni in Pd-Ni compared to Ag in Pd-Ag favoured higher charge polarization between the metals in the Pd-Ni system enhancing the CO2 to FA conversion. The experimental observations are well supported by the DFT calculations.

}, issn = {2050-7488}, doi = {10.1039/d2ta03690h}, author = {Cherevotan, Arjun and Ray, Bitan and Yadav, Anish and Bagchi, Debabrata and Singh, Ashutosh Kumar and Riyaz, Mohd and Churipard, Sathyapal R. and Naral, Vinay and Kaur, Komalpreet and Gautam, Ujjal K. and Vinod, Chathakudath P. and Peter, Sebastian C.} }