@article {47600, title = {Aqueous methanol to formaldehyde and hydrogen on Pd/TiO2 by photocatalysis in direct sunlight: structure dependent activity of nano-Pd and atomic Pt-coated counterparts}, journal = {ACS Applied Energy Materials}, volume = {4}, year = {2021}, month = {NOV }, pages = {13347-13360}, type = {Article}, abstract = {In the present investigation, facet-controlled Pd nanoparticles with nanocube (Pd-NC) and truncated octahedron (Pd-TO) morphologies, and their counterparts with half-a-monolayer of atomic Pt coated (0.5 theta(Pt)-Pd-NC and 0.5 theta(Pt)-Pd-TO) surfaces were prepared. All of them were characterized and evaluated as cocatalyst after supporting them on commercial titania (P25) (Pd-NC/P25, Pd-TO/P25, 0.5 theta(Pt)-Pd-NC/P25, and 0.5 theta(Pt)-Pd-TO/P25) under direct sunlight and/or one sun conditions for the oxidation of methanol to formaldehyde along with solar hydrogen production. Pd-NC/P25 shows higher activity for hydrogen generation compared to Pd-TO/P25; however, activity reversal occurs with the above cocatalysts, but, after Pt-coating with further enhanced activity. The highest conversion of methanol (0.2 mu mol/h.mg) to 100\% selective formaldehyde was observed with 0.5 theta(Pt)-Pd-TO/P25, while other catalysts show significantly lower methanol conversion in the following order: 0.5 theta(Pt)-Pd-TO/P25 > 0.5 theta(Pt)-Pd-NC/P25 > Pd-NC/P25 > Pd-TO/P25. Pt-coated on (111) facets of Pd-TO simulates the activity associated as that of Pt(111) facets and demonstrating the highest and facet dependent activity. The present study is truly in resonance with exploiting the surface properties for heterogeneous catalysis, and highlights that less than a monolayer of Pt is sufficient to simulate the activity as that of bulk Pt. It is worth exploring this concept to other metals and substrates too.}, keywords = {heterogeneous catalysis, Nanomaterials, Oxidation, Photocatalysis, surface modification}, issn = {2574-0962}, doi = {10.1021/acsaem.1c03080}, author = {Nalajala, Naresh and Salgaonkar, Kranti N. and Chauhan, Inderjeet and Mekala, Siva Prasad and Gopinath, Chinnakonda S.} } @article {48704, title = {Baby step in assembling and integrating the components of an artificial photosynthesis device with forced heterojunctions towards improved efficiency}, journal = {Journal of Materials Chemistry A}, volume = {11}, year = {2023}, month = {JUL }, pages = {15168-15182}, type = {Article}, abstract = {

How to achieve unassisted, economical, scalable, and sustainable artificial photosynthesis for liquid fuels/products with improved solar-to-fuel efficiency (STFE) to address a carbon-neutral economy remains a big question. To a large degree, the extent of charge separation at heterojunction interfaces and charge utilization determine the STFE. Towards this, BiVO3 is assembled from ionic-precursors into TiO2 pores, and integrated structurally and electronically with TiO2 on calcination as BiVO4 quantum dots (BVQDs). BVQDs in TiO2 (BVT) pores lead to an all-inorganic system with a sub-quadrillion number of heterojunctions in a 1 cm(2) device (contains similar to 25 mu g of BiVO4 (similar to 2.5 wt\%) in the nanopores of similar to 975 mu g of TiO2 (similar to 97.5 wt\%)) and facilitate artificial photosynthesis. We demonstrate 31-38\% STFE with a photon to chemical conversion turn over frequency (ToF(P2C)) of 2.73 s(-1) with a 1 cm(2) wireless BiVO4-TiO2 artificial leaf (BVT-AL) device for HCHO and CH3OH. The sequential nature of CO2 reduction to HCHO and then to CH3OH is evident from the reaction results. (CO2)-C-13 isotopic labeling experiments confirm that the input CO2 is the source for product formation. A large increase in the photocurrent density and incident photon-to-current efficiency (IPCE) of BVT, over 100\% for the BiVO4 photoanode in visible light, demonstrates and supports efficient visible light absorption, charge separation and migration to the redox sites. A device has been demonstrated to show sustainable activity in direct sunlight, and addresses scalability from 1 to 9 cm(2). Assuming no change (50\% decrease) in the STFE, a 6.74 m(2) device is expected to convert 1 (0.5) kg h(-1) CO2 into C1-oxygenates in sunlight. DFT calculations carried out with anatase TiO2 (101) and BiVO4 (121) interfaces support many of the experimental findings, including electron flow from the latter to the former, and interaction of the oxygen of TiO2 with BiVO4 and vice versa at the interface towards forced heterojunctions.

}, issn = {2050-7488}, doi = {10.1039/d3ta01850d}, author = {Salgaonkar, Kranti N. and Bajpai, Himanshu and Mhamane, Nitin B. and Nalajala, Naresh and Chauhan, Inderjeet and Thakkar, Kavita and Joshi, Kavita and Gopinath, Chinnakonda S.} } @article {48272, title = {Nanostructured Co-doped BiVO4 for efficient and sustainable photoelectrochemical chlorine evolution from simulated sea-water}, journal = {Dalton Transactions}, volume = {52}, year = {2023}, month = {FEB}, pages = {2051-2061}, type = {Article}, abstract = {

The co-production of hydrogen and chlorine from sea-water splitting could be a potential, sustainable and attractive route by any method. However, challenges to overcome are many, and critically, the sustainability and operating potential of the electrocatalyst are important. In this work, we report on Co-doping in the BiVO4 (Co-BV) crystal lattice and employed the same as the photoanode; Co-BV exhibits a photocurrent of 190 mu A cm(-2) at 1.1 V vs. RHE (the reversible hydrogen electrode) in the acidic sodium chloride solution (pH 2.3) under one sun illumination. The best-performing photoanode, with 0.05 mol\% of Co doping (0.05 Co-BV), selectively produced active chlorine with 92\% faradaic efficiency at 1.1 V vs. RHE by successfully suppressing the kinetically sluggish oxygen evolution reaction (OER) and the stability of the catalyst was demonstrated for up to 20 h. This is the lowest operating potential reported for the chlorine evolution reaction (CER), thus far. The overpotential required for CER with 0.05 Co-BV is lower than that of OER, which leads to selective CER at 1.1 V (vs. RHE). Co-doping into the BiVO4 lattice decreases the charge transfer resistance and enhances the CER kinetics due to its structural and electronic integration with the BV lattice. We demonstrate that Co-doping also improves the lifetime of the charge carrier and enhances the current density of CER and sustainability of the catalyst.

}, issn = {1477-9226}, doi = {10.1039/d2dt03369k}, author = {Chauhan, Inderjeet and Patra, Kshirodra Kumar and Bajpai, Himanshu and Mhamane, Nitin B. and Salgaonkar, Kranti N. and Gopinath, Chinnakonda S.} } @article {48273, title = {Selective and generic photocatalytic oxidation of alcohol with Pd-TiO2 thin films: butanols to butanal/butanone with different morphologies of Pd and 0.5 theta(Pt)-Pd counterparts}, journal = {Chemistry-An Asian Journal}, volume = {18}, year = {2023}, month = {MAR}, type = {Article}, abstract = {

The present study reports on the photocatalytic oxidation of butanols to butanal/butanone using thin film form of facet-dependent nano-Pd supported on commercial TiO2 under one-sun condition and demonstrates the generic nature. Pd-nanocube (Pd-NC(100)), Pd-truncated octahedron (Pd-TO (100) and (111)), polycrystalline (Pd-PC), and their counterparts with half-a-monolayer Pt-coated on Pd (0.5 theta(Pt)-Pd)) have been used as co-catalyst. A potentially scalable thin film form of Pd/TiO2 photocatalyst, prepared by drop-casting method, has been employed to study oxidation of n-butanol, 2-butanol, and iso-butanol to corresponding aldehyde/ketone. 100\% selectivity is demonstrated to respective aldehyde/ketone with any catalyst used in the present study with varying degree of butanols conversion by NMR. 0.5 theta(Pt)-Pd-TO/TiO2 shows the highest conversion of 2-butanol to butanone (13.6\% in 4 h). Continuous 10 h of reaction with the most active 0.5 theta(Pt)-Pd-TO/P25 catalyst demonstrates 31\% conversion of 2-butanol to butanone, and catalyst recyclability has been demonstrated. The present protocol can be scalable to large scales to maximize the conversion in direct sunlight. Due to its generic nature, the current method can also be applied to many other alcohols and substrate molecules.

}, keywords = {energy conversion, Nanomaterials, Oxidation, Photocatalysis, Sustainability}, issn = {1861-4728}, doi = {10.1002/asia.202201239}, author = {Salgaonkar, Kranti N. and Kale, Sandip R. and Nalajala, Naresh and Mansuri, Sayana and Gopinath, Chinnakonda S.} } @article {49463, title = {Lead-free Cs2AgBiCl6 double perovskite: experimental and theoretical insights into the self-trapping for optoelectronic applications}, journal = {ACS Physical Chemistry Au}, volume = {4}, year = {2024}, month = {JUL}, pages = {476{\textendash}489}, type = {Article}, abstract = {

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs2AgBiCl6\ DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental{\textendash}computational approach is employed to investigate the optoelectronic properties of pure and doped Cs2AgBiCl6\ (Fe{\textendash}Cs2AgBiCl6) perovskites. Successful incorporation of Fe3+\ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe{\textendash}Cs2AgBiCl6\ DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton{\textendash}phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis.

}, doi = {https://doi.org/10.1021/acsphyschemau.4c00008}, author = {Rahane, Swati N. and Rahane, Ganesh K. and Mandal, Animesh and Jadhav, Yogesh and Godha, Akshat and Rokade, Avinash and Shah, Shruti and Hase, Yogesh and Waghmare, Ashish and Saykar, Nilesh G. and Roy, Anurag and Salgaonkar, Kranti N. and Dubal, Deepak and Makineni, Surendra K. and Dzade, Nelson Y. and Jadkar, Sandesh R. and Rondiya, Sachin R.} } @article {49600, title = {Enhanced mid-visible light absorption and long-lived charge carriers in an electronically and structurally integrated BiVO4-TiO2 photoanode for efficient artificial photosynthesis applications}, journal = {Nanoscale}, volume = {17}, year = {2025}, month = {MAY}, pages = {12738-12750}, type = {Article}, abstract = {

The ever-increasing demand for sustainable solutions for eliminating environmental pollutants, solar energy harvesting, water splitting, etc. have led to the design and development of novel materials to achieve the desired result. In this regard, structurally and electronically integrated (SEI) BiVO4-TiO2 (SEI-BVT) with abundant heterojunctions has emerged as a promising entity for efficient charge separation, which in turn enhances artificial photosynthesis (APS) activity. The present work adopted a unique synthetic strategy using SILAR to fabricate SEI-BVT from ionic precursors (Bi3+ and VO43-) into the pores of TiO2, exhibiting benchmark APS efficiency compared to the individual components. This preparation results in approximately 180 trillion uniformly distributed heterojunctions in 1 mg cm-2 of the SEI-BVT photoanode material. Charge carriers in SEI-BVT and BiVO4 are similar; however, the recombination is highly hindered when SEI-BVT heterojunctions are formed in the former. Our earlier work demonstrated 31-38\% solar-to-fuel efficiency (STFE) with BiVO4-TiO2 for APS in the presence of the Pd-nanocube co-catalyst. The emphasis of the current work is to explore the dynamics of the light-induced processes in these heterojunctions to understand the interfacial charge transfer process. Femtosecond transient absorption (TA) spectroscopy has been employed to monitor the excited state dynamics. Our results show that new trap states have evolved under light illumination, which are significantly long-lived and hinder charge recombination, and consequently enhance STFE. A significantly large number of charge carriers exhibit a lifetime of \>\> 6 ns with visible light photons, at least up to 720 nm, which is higher than the band-gap absorption onset at 490 nm for SEI-BVT compared to bulk BiVO4. The rate of formation of charge carriers is significantly affected in the heterojunctions.

}, issn = {2040-3364}, doi = {10.1039/d5nr00723b}, author = {Jha, Vikas Kumar and Salgaonkar, Kranti N. and Saha, Avishek and Gopinath, Chinnakonda S. and Iyer, E. Siva Subramaniam} } @article {49773, title = {Synthesis of Pd-integrated carbon Dot@TiO2 thin film for photocatalytic glycerol reforming reaction for producing hydrogen}, journal = {Chemistry-an Asian Journal}, volume = {20}, year = {2025}, month = {NOV}, type = {Article}, abstract = {

A series of thin-film photocatalysts comprising TiO2 modified with carbon dots (CDs) dispersed either with palladium (Pd-CD/TiO2) or nickel (Ni-CD/TiO2) were synthesized via solid-state and wet-impregnation methods. Morphological characterization (HR-TEM, SEM-EDS) confirmed the anatase phase of TiO2 and the atomic dispersion of metal-integrated CDs on its surface. UV-vis DRS and XPS analyses revealed a marginal red shift in band-gap and the presence of sp2-hybridized graphitic carbon, and metal-carbon interactions, indicating enhanced light absorption and charge separation through Schottky junctions. Under direct sunlight illumination, Pd-CD/TiO2 thin film exhibited superior hydrogen yield (1167 mu mol g-1 h-1) and maintained stability over 25 h, outperforming Ni-CD/TiO2 (494 mu mol g-1 h-1) and bare TiO2 (166 mu mol g-1 h-1) photocatalyst thin films. Concurrent glycerol oxidation at neutral pH (pH similar to 7) yields glycolaldehyde (41\% selectivity), formic acid, and dihydroxyacetone as value-added products. Enhanced photocurrent density and lower impedance of Pd-CD/TiO2 corroborate improved charge carrier separation and dynamics. The results demonstrate that Pd-CD synergistically improves the photocatalytic performance of the Pd-CD/TiO2 for sustainable hydrogen generation and selective biomass valorization.

}, keywords = {Glycerol oxidation, Graphitic carbon dots, hydrogen production, Photocatalysis, titania}, issn = {1861-4728}, doi = {10.1002/asia.202500757}, author = {Abraham, Athira and Salgaonkar, Kranti N. and Nivedhitha, Thazhath R. and Ekal, Vishal Ashok and Kondhekar, Deepali and Chakraborty, Shubhankar and Gopinath, Chinnakonda S. and Saha, Avishek} } @article {49844, title = {Utilizing nature{\textquoteright}s endowment: artificial leaf concept for methane activation to C-C coupled ethanol or ethylene}, journal = {Sustainable Energy \& Fuels}, volume = {9}, year = {2025}, month = {DEC}, pages = {6798-6810}, type = {Article}, abstract = {

Methane activation (MA) to platform chemicals under ambient conditions still remains an open challenge to be fully realised. The present work shows the fabrication of CeVO4 quantum dots (CV-QDs) by a bottom-up approach; they are assembled from Ce3+ and metavanadate ions, and structurally and electronically integrated into the micro-/meso-pores of TiO2 (CV-QD-TiO2 (CVT)), demonstrating the conversion of MA to ethanol/ethylene by visible light-driven photocatalysis. CV-QDs in confined pores modify the quantum confinement effects and are characterized by physicochemical methods. The current synthetic strategy is potentially scalable and results in sub-quadrillion heterojunctions in a 1 mg CVT photoanode spread over 1 cm2. MA with CVT under one-sun conditions demonstrates similar to 100\% selectivity to ethanol, yielding 4.36 mu mol h-1 cm-2, with a solar-to-fuel efficiency (STFE) of 0.56. Further, by employing a co-catalyst, significant STFE (5.08) and yield (39.5 mu mol h-1 cm-2) are achieved selectively towards ethylene. A deliberate addition of methanol increases the rate of ethanol production by 17.2 times, indicating that the methyl-methoxy interaction is the origin of C-C coupling. Weight is normalized to a gram of CV-QDs in a large area CVT photoanode to yield 109 mmol h-1 gCV-QD-1 of ethanol and 988 mmol h-1 gCV-QD-1 of ethylene. Enhanced activity and selectivity towards the C2-product is attributed to band-edge modulation and trillions of heterojunctions, which in turn facilitate charge separation and charge transfer for effective charge utilisation at redox sites.

}, issn = {2398-4902}, doi = {10.1039/d5se01178g}, author = {Kanungo, Subhashree S. and Mishra, Abhaya Kumar and Avani, Mangaladasan J. and Bajpai, Himanshu and Salgaonkar, Kranti N. and Javaregowda, Bharathkumar H. and Gopinath, Chinnakonda S.} } @article {49792, title = {Visible-light-driven photocatalytic glycerol oxidation to value-added and highly selective glyceric/lactic acid}, journal = {ChemiCatChem}, volume = {17}, year = {2025}, month = {SEP}, type = {Article}, abstract = {

Achieving economical and sustainable artificial photosynthesis (APS) in direct sunlight for liquid fuel production with high efficiency remains an important challenge. A major obstacle in the photoelectrochemical (PEC) oxidation of organic compounds is attaining high selectivity with the desired product(s). This study introduces a novel strategy by integrating BiVO4 quantum dots (BVQDs), structurally and electronically, into the nanopores of commercial TiO2 (BVT for BVQDs integrated in pores of TiO2) to improve solar-driven photocatalysis. The band gap of the BVT photoanode decreases to 2.53 eV as compared to pure TiO2 (3.2 eV), which enhances visible light absorption and charge separation. BVT with Pt as a co-catalyst acts as an APS system, which selectively oxidizes glycerol into lactic acid (100\% selectivity at 1 mM glycerol) and glyceric acid (98\% selectivity at 100 mM), while simultaneously generating green hydrogen. Selectivity of the product can be further controlled by anaerobic or aerobic conditions as well as the length of the reaction time. Direct integration of BVQDs into TiO2 mesopores significantly enhances charge separation as well as utilization at redox sites. Current work provides key insights into optimizing photocatalytic conditions for highly selective value-added chemical production, which highlights the sustainability and efficacy of TiO2-based semiconductors with quantum dot integration.

}, keywords = {energy conversion, Energy storage, Photocatalysis, Quantum material, solar energy}, issn = {1867-3880}, doi = {10.1002/cctc.202500641}, author = {Kulkarni-Sambhare, Mukta and Salgaonkar, Kranti N. and Saha, Avishek and Gopinath, Chinnakonda S.} }