@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 {48450, title = {Intrinsic charge polarization in Bi19S27Cl3 nanorods promotes selective C-C coupling reaction during photoreduction of CO2 to ethanol}, journal = {Advanced Materials}, volume = {35}, year = {2023}, month = {FEB}, type = {Article}, abstract = {

Obtaining multi-carbon products via CO2 photoreduction is a major catalytic challenge involving multielectron-mediated C-C bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO2 conversion efficiency and product selectivity. Alternatively, robust metal centers having asymmetric charge distribution can effectuate C-C coupling reaction through the stabilization of intermediates, for desired product selectivity. However, generating inherent charge distribution in a single component catalyst is a difficult material design challenge. Here, a novel photocatalyst, Bi19S27Cl3, is presented which selectively converts CO2 to a C-2 product, ethanol, in high yield under visible light irradiation. Structural analysis through transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveals the presence of charge polarized bismuth centers in Bi19S27Cl3. The intrinsic electric field induced by charge polarized bismuth centers renders better separation efficiency of photogenerated electron-hole pair. Furthermore, charge polarized centers yield better adsorption of CO* intermediate and accelerate the rate determining C-C coupling step through the formation of OCCOH intermediate. Formation of these intermediates is experimentally mapped by in situ Fourier-transform infrared spectroscopy and further confirmed by theoretical calculation.

}, keywords = {C-C coupling, charge polarization, CO2 reduction, Ethanol, Photocatalysis}, issn = {0935-9648}, doi = {10.1002/adma.202205994}, author = {Das, Kousik and Das, Risov and Riyaz, Mohd and Parui, Arko and Bagchi, Debabrata and Singh, Ashutosh Kumar and Singh, Abhishek Kumar and Vinod, Chathakudath P. and Peter, Sebastian C.} } @article {48962, title = {Wurtzite CuGaS2 with an in-situ-formed CuO layer photocatalyzes CO2 conversion to ethylene with high selectivity}, journal = {Angewandte chemie-international edition}, volume = {62}, year = {2023}, month = {FEB 20}, type = {Article}, abstract = {

We present surface reconstruction-induced C-C coupling whereby CO2 is converted into ethylene. The wurtzite phase of CuGaS2. undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO2 to ethylene (C2H4). Upon illumination, the catalyst efficiently converts CO2 to C2H4 with 75.1 \% selectivity (92.7 \% selectivity in terms of R-electron) and a 20.6 mu mol g(-1) h(-1) evolution rate. Subsequent spectroscopic and microscopic studies supported by theoretical analysis revealed operando-generated Cu2+, with the assistance of existing Cu+, functioning as an anchor for the generated *CO and thereby facilitating C-C coupling. This study demonstrates strain-induced in situ surface reconstruction leading to heterojunction formation, which finetunes the oxidation state of Cu and modulates the CO2 reduction reaction pathway to selective formation of ethylene.

}, keywords = {C-C coupling, charge polarization, CO2 reduction, Photocatalysis}, issn = {1433-7851}, doi = {10.1002/anie.202216613}, author = {Chakraborty, Subhajit and Das, Risov and Riyaz, Mohd and Das, Kousik and Singh, Ashutosh Kumar and Bagchi, Debabrata and Vinod, Chathakudath P. and Peter, Sebastian C.} } @article {49219, title = {Photocatalytic regeneration of reactive cofactors with inP quantum dots for the continuous chemical synthesis}, journal = {ACS Catalysis}, volume = {14}, year = {2024}, month = {APR}, pages = {6740-6748}, type = {Article}, abstract = {

The shuttling of redox-active nicotinamide cofactors between the light and dark cycles is the key to the continuous production of biomass in photosynthesis. The replication of such processes in artificial photosynthetic systems demands fast photoregeneration as well as simultaneous integration of these nicotinamide cofactors into the dark cycle. Here, we report the design of an artificial photosynthetic system for the continuous production of butanol via the constant photoregeneration and consumption of nicotinamide cofactors, powered by an indium phosphide quantum dot (InP QD) photocatalyst and alcohol dehydrogenase (ADH) enzyme, respectively. A strong electrostatic attraction between the oppositely charged InP QDs and electron mediators significantly enhanced the charge extraction and utilization processes, enabling a fast (similar to 30 min, with a turn over frequency of similar to 1333 h(-1)), quantitative (\>99\%), and selective photoregeneration of enzymatically active nicotinamide cofactors in the light cycle. These photoregenerated nicotinamide cofactors were further coupled in the dark cycle to trigger the ADH oxidoreductase enzyme for the production of butanol, via sequential as well as simultaneous light-dark cycles. The amount of butanol produced under simultaneous light-dark cycles was higher than the stoichiometric limit, proving the constant regeneration and consumption of nicotinamide cofactors in light and dark cycles, respectively. Thus, a proper design and integration of the InP QD-based photocatalytic cycle with the enzymatic cycle led to the effective electron shuttling between light and dark cycles, as seen in photosynthesis.

}, keywords = {artificial photosynthesis, biologicalcofactors, charge transfer, indiumphosphide, Photocatalysis, quantum dots}, issn = {2155-5435}, doi = {10.1021/acscatal.4c00817}, author = {Chakraborty, Indra Narayan and Jain, Vanshika and Roy, Pradyut and Kumar, Pawan and Vinod, Chathakudath P. and Pillai, Pramod P.} } @article {49695, title = {Dopant and exfoliation induced simultaneous modification of charge density and C--C coupling sites for efficient CO2 photoreduction to ethylene}, journal = {Angewandte Chemie-International Edition}, volume = {64}, year = {2025}, month = {JUL}, pages = {e202423471}, type = {Article}, abstract = {

The photochemical conversion of CO2 into C2+ products has emerged as an attractive method for synthesizing valuable chemicals and fuels using abundant solar energy. However, the challenge lies in enhancing the efficiency and selectivity of C2+ product formation. In this study, we employed a heteroatom doping strategy to optimize the photocatalytic parameters and achieve excellent efficiency and selectivity in the photocatalytic CO2 reduction to C2+ product formation. Our experimental analysis revealed that the local electronic structure of the catalyst, modified by In-doping, enables enhanced efficiency. Additionally, the incorporation of Cu facilitates the coupling of C1 intermediates, resulting in excellent selectivity towards C2+ products. The CO2 reduction performance is further enhanced through exfoliation, which increases the exposure of active sites and extends the charge carrier lifetime by reducing the charge diffusion length. We report that the rate of formation of C2H4 reached 54.3 mu molh(-1)g(-1) with an outstanding selectivity of 91\% over the exfoliated CuIn-doped AgBiP2S6 catalyst. By elucidating the role of heteroatom doping and exfoliation in enhancing both the efficiency and selectivity of C2+ product formation, our study contributes to advancing the development of sustainable and efficient photocatalytic CO2 conversion technologies.

}, keywords = {C \& horbar, C coupling, CO2 reduction, Doping, Exfoliation, Photocatalysis}, doi = {10.1002/anie.202423471}, author = {Das, Kousik and Chakraborty, Subhajit and Kediya, Siddhi and Singh, Ashutosh Kumar and Das, Risov and Mondal, Soumi and Riyaz, Mohd and Goud, Devender and Dutta, Nilutpal and Vinod, Chathakudath P. and Peter, Sebastian C.} }