@article {48490, title = {Can Li atoms anchored on boron- and nitrogen-doped graphene catalyze dinitrogen molecules to ammonia? a DFT study}, journal = {ChemPhysChem}, volume = {24}, year = {2023}, month = {JUN}, type = {Article}, abstract = {

The most successful electrochemical conversion of ammonia from dinitrogen molecule reported to date is through a Li mediated mechanism. In the framework of the above fact and that Li anchored graphene is an experimentally feasible system, the present work is a computational experiment to identify the potential of Li anchored graphene as a catalyst for N-2 to NH3 conversion as a function of (a) minimum number of Li atoms needed for anchoring on graphene sheets and (b) the role of chemical modification of graphene surfaces. The studies bring forth an understanding that Li anchored graphene sheets are potential catalysts for ammonia conversion with preferential adsorption of N-2 through end-on configuration on Li atoms anchored on doped and pristine graphene surfaces. This mode of adsorption being characteristic of Nitrogen Reduction Reaction (NRR) through enzymatic pathway, examination of the same followed by analysis of electronic properties demonstrates that tri-Li atoms (Tri Atom Catalysts, TACs) are more efficient as catalysts for NRR as compared to two Li atoms (Di Atom Catalysts, DACs). Either way, the rate determining step was found to be *NH2 -\>*NH3 step (mixed pathway) with Delta G(max)=1.02 eV and *NH2-*NH3 -\>*NH2 step (enzymatic pathway) with Delta G(max)=1.11 eV for 1B doped TAC and DAC on graphene sheet, respectively. Consequently, this work identifies the viability of Li anchored graphene based 2-D sheets as hetero-atom catalyst for NRR.

}, keywords = {computational chemistry, Graphene Sheet, heterogeneous catalysis, Li Nanoparticles, Nitrogen Reduction Reaction}, issn = {1439-4235}, doi = {10.1002/cphc.202200750}, author = {Verma, Tushar Singh and Samal, Pragnya Paramita and Selvaraj, Kaliaperumal and Krishnamurty, Sailaja} } @article {49055, title = {Computational identification of most potent atom pair catalysts for electrocatalytic nitrogen reduction reaction over hydrogen evolution reaction}, journal = {Inter.}, volume = {58}, year = {2024}, month = {MAR }, pages = {1345-1358}, type = {Article}, abstract = {

Robust electrocatalytic atom pair compositions (APCs) where Nitrogen Reduction Reaction (NRR) is more enhanced over competing Hydrogen Evolution Reaction (HER) is searched for using computational studies based on Density Functional Theory based methods. Atomic pairs are anchored on mechanically and thermally stable graphene surfaces. A wide range of transition metal based atom pair compositions from 3d, 4d, and 5d groups are systematically investigated for reduction of dinitrogen molecule with lower reduction barrier as compared to HER. APR compositions of Ni-Rh with an overall limiting potential of -0.22 V, Fe-W with an overall limiting potential of -0.26 V and Co-Pt with an overall limiting potential of -0.28 V are identified as the most potent atomic pairs for enhanced nitrogen reduction reaction over the HER. Finally, the performance of most potent composition, viz., Ni-Rh is validated to be consistent with respect to their thermodynamic stability and performance within the solvent effects.

}, keywords = {Atom pair catalysts, Density Functional Theory (DFT), Electrochemical nitrogen reduction reaction (eNRR), hydrogen evolution reaction (HER), IR stretching frequencies, N-N bond length}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.01.203}, author = {Verma, Tushar Singh and Dar, Afshana Hassan and Dar, Manzoor Ahmad and Selvaraj, Kaliaperumal and Krishnamurty, Sailaja} } @article {49283, title = {Triazatruxene amine donor-based visible-light-responsive unsymmetrical squaraine dyes for dye-sensitized solar cells}, journal = {ACS Applied Energy Materials}, volume = {7}, year = {2024}, month = {SEP}, pages = {7982-7991}, type = {Article}, abstract = {

Optimized charge-transfer dynamics at the dye-TiO2/electrolyte interface are required for an enhanced dye-sensitized solar cell (DSSC) device performance. Such an optimized interface enhances the charge-injection, dye-regeneration, and diminished charge-recombination processes, synergistically enhancing the device efficiency. In this study, octupolar-structured sensitizers are designed to improve the interaction between the dye and the redox electrolyte for increasing the dye-regeneration process upon photoexcitation. Accordingly, a set of unsymmetrical squaraine dyes with indoline and triazatruxene amine donor-based D-A-D dyes are designed (KV1-KV3), synthesized, and sensitized with a semiconducting metal oxide (TiO2) film. The sensitizer forms a monolayer on the TiO2 surface, leading to a dye-dye interaction, which broadens the absorption spectrum. The N atom of the triazatruxene amine donor was left unsubstituted in KV1, whereas a hexyl chain was installed in KV2 and KV3 and a branched alkyl chain was installed on the core N atoms in KV3 to control the self-assembly of dyes on the TiO2 surface. Self-assembly of alkyl groups wrapped in KV1-KV3 dyes on the TiO2 surface aids surface passivation and broadens the absorption profile, improving the light-harvesting capabilities. The DSSC devices based on KV2 exhibited a high power conversion efficiency of 7.85\% (V-oc = 794 mV, J(sc) = 14.76 mA/cm(2), and FF = 67\%), with an onset incident photon-to-current conversion efficiency response from 680 nm.

}, keywords = {aggregationof dyes, Dye-sensitized solar cells, metal-free organic dyes, self-assembly of dye, squaraine dyes, triazatruxene}, issn = {2574-0962}, doi = {10.1021/acsaem.4c01591}, author = {Ingole, Kiran Balaso and Deshmukh, Shivdeep Suresh and Verma, Tushar Singh and Krishnamurty, Sailaja and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49506, title = {Effect of doping on electrocatalytic dehydrogenation and hydrogenation of methyl decalin-methyl naphthalene system}, journal = {Journal of Physical Chemistry C}, volume = {129}, year = {2025}, month = {JAN}, pages = {2367-2380}, type = {Article}, abstract = {

The hydrogen economy can benefit from the use of liquid organic hydrogen carriers (LOHCs) for cross-continent hydrogen transportation in the future. However, dehydrogenation and hydrogenation of hydrogen require catalytic systems. Current research emphasizes selective Pt/Rh doping of Fe, Co, and Ni surfaces as catalysts for the dehydrogenation and hydrogenation of the methyl naphthalene-methyl decalin LOHC system, which has more than 7\% hydrogen weight capacity and meets the practical requirements established by the European Union and the United States Department of Energy. Density functional theory-based computational techniques demonstrate how the chemical modification of these surfaces with a Pt and Rh single-atom catalyst (SAC) can improve the efficiency of dehydrogenation and hydrogenation. With a sustainable method, electrochemical dehydrogenation and hydrogenation on these robust surfaces produce effective hydrogen storage for extended periods without losing hydrogen. Furthermore, optimal results for the hydrogenation of 2-methyl naphthalene on Fe-Rh SAC with path-determining step (PDS) = 0.98 eV and dehydrogenation of 1-methyl decalin on Fe-Pt SAC with PDS = 1.49 eV were obtained for the most effective active sites for the enhanced electrochemical process. This study offers new possibilities for the catalytic dehydrogenation and hydrogenation of LOHC systems by highlighting the impact of doping on transition-metal-based catalysts.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.4c07598}, author = {Verma, Tushar Singh and Selvaraj, Kaliaperumal and Krishnamurty, Sailaja} } @article {49789, title = {Harnessing AEM electrolyzer-level performance through strategically designing the electronic structure of electrocatalysts, enabling dynamic functional switching}, journal = {ACS Catalysis}, volume = {15}, year = {2025}, month = {DEC }, pages = {19968-19983}, type = {Article}, abstract = {

The anion exchange membrane water electrolyzer (AEMWE) is a promising technology for cost-effective hydrogen production. To promote its development and adoption, targeted efforts are focused on finding non-platinum group metal (non-PGM) electrocatalysts that efficiently facilitate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Nickel sulfides (NiS) are effective OER catalysts; however, they suffer due to leaching-related instability at electrolyzer stack operational conditions. We introduce a rational non-PGM design that enhances stability during the OER while excelling at the HER, showcasing molecular-level insights for a scalable AEMWE zero-gap stack device. NiS coating is applied to the Al-metal-organic framework supported by 3D porous nickel foam (NSMA), leading to charge localization at the interface, which helps in OER by requiring only 322 millivolts at 100 mA cm-2. The main innovation in the NSMA design is a controlled electroreduction process that converts the Millerite phase into Ni3S2, a catalyst (rNSMA). This transformation leads to charge delocalization at the surface and a low overpotential of -80 mV at -100 mA cm-2 for the HER. In a full cell, this catalyst duo requires an overpotential of 1.49 V, outperforming the commercial Pt/Ru catalyst pair at 1.58 V. In a scaled-up 12.96 cm2 AEM electrolyzer single-cell stack, current density rose from 398 to 1062 mA/cm2, maintained for over 100 h at high temperatures, achieving 99\% Faradaic efficiency and 100\% hydrogen purity. The AEM electrolyzer cell shows a good energy efficiency of 45.50 kWh/kg and a cell efficiency of 86.59\%. Detailed studies, including DFT analyses, revealed that electronic structure modification enhances charge delocalization, driving its impressive performance on an industrially significant scale.

}, keywords = {anion exchangemembrane water electrolyzer (AEMWE), charge transfer, density functional theory(DFT), HER, nickel sulfide, OER}, issn = {2155-5435}, doi = {10.1021/acscatal.5c07117}, author = {Kumar, Sonu and Verma, Tushar Singh and Selvaraj, Kaliaperumal} } @article {49678, title = {In silico designing of electrocatalysts for hydrogen evolution reaction: a focus on titanium metal-based diboride monolayers}, journal = {International Journal of Hydrogen Energy}, volume = {133}, year = {2025}, month = {JUN }, pages = {91-100}, type = {Article}, abstract = {

Enhancing the efficiency of Hydrogen Evolution Reaction (HER) using chemically modified electrocatalytic titanium diboride surfaces with transition metal-based Single Atom Catalysts (SACs) is illustrated using Density Functional Theory (DFT) based methods employing solvent effects. With higher surface concentrations of nonmetal boron rather than titanium metal, these highly conductive, extremely hard, chemically, and thermally stable electrocatalysts are more cost-effective and superior to their MBene analogs. A systematic analysis of these transition metal-based SACs from the 3d, 4d, and 5d groups embedded in TiB2 monolayer for its HER activity reveals the reduction in limiting potential. As the most effective SAC for improved HER, Zn@TiB2 SAC has a limiting potential of 0.08 eV in acidic and 0.21 eV in alkaline media. The higher exchange current density of Zn@TiB2 (5.74 x 10-5 A cm-2), which exceeds most previously reported electrocatalysts, indicates exceptional HER performance. This work shows that transition metal boride electrocatalysts are economically viable for HER and pave a path for experimentalists.

}, keywords = {AIMD, D -band center, DFT, HER, SAC}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.04.482}, author = {Shivankar, Bhavana R. and Verma, Tushar Singh and Krishnamurty, Sailaja} } @article {49619, title = {Mimicking characteristics of cast iron for enhanced electrocatalytic dehydrogenation of methane}, journal = {Fuel}, volume = {381}, year = {2025}, month = {FEB}, pages = {133674}, type = {Article}, abstract = {

Enhancing the efficiency of methane dehydrogenation through chemical modification of electrocatalytic iron surfaces with impurities that resemble cast iron properties is demonstrated computationally using Density Functional Theory methodologies. Investigating methane dehydrogenation on thermally stable Fe surfaces with discrete planes and anchoring impurities such as Al, C, and Si minimized reduction barriers. Electrochemical treatment of methane on these robust surfaces yields clean hydrogen and carbon-based compounds, such as carbon nanomaterials and carbon black. As for the most efficient active sites for enhanced methane dehydrogenation, the active plane 100 with 5.5 \% C impurities and 0.51 eV reduction barrier is determined to be the most dependable, followed by the active plane 110 with 5.5 \% Si impurities and the lower 0.98 eV reduction barrier. Utilizing CI-NEB (Nudged Elastic Band), the dissociation barrier investigation established the electrolytic catalysts{\textquoteright} performance. This work paves the way for experimentalists and demonstrates the economic viability of Fe-based catalysts for the Catalytic Dehydrogenation of Methane.

}, keywords = {carbon black, Density Functional Theory (DFT), Dry methane reforming (DMR), Electrochemical methane dehydrogenation, Fe surface catalyst}, issn = {0016-2361}, doi = {10.1016/j.fuel.2024.133674}, author = {Verma, Tushar Singh and Devi, R. Nandini and Krishnamurty, Sailaja} } @article {49791, title = {Rational design of hydrophobic Cu/CuO electrodes for electrochemical oxygenation of tetralin: a strategic approach}, journal = {ChemSusChem}, volume = {18}, year = {2025}, month = {AUG }, type = {Article}, abstract = {

Electro-organic synthesis presents a sustainable and practical alternative to traditional organic synthesis methods, which typically utilize harsh reagents and require energy-intensive conditions. Nevertheless, the challenge of achieving satisfactory conversion and selectivity rates in electrocatalytic oxidation using a non-platinum group metal (PGM) catalyst pair still needs to be addressed. This study demonstrates the application of a non-PGM-based catalyst pair for the electrocatalytic oxidation of tetralin to 1-tetralone, a highly demanded raw material in the pharma industry. Copper electrodeposited on teflonated carbon paper combined with copper foam as the electrocatalyst pair has demonstrated impressive conversion and selectivity ratios to electro-synthesize 1-tetralone at room temperature and atmospheric pressure. The optimal choice of a non-PGM catalyst, ideal mass loading, and a unique electrode configuration resulted in an ultimate conversion of about 99\% of tetralin and 1-tetralone selectivity -93.7\%, yield -92.6\%. The reaction pathway associated with the electrochemical phenomena is supported by first principles-based density functional theory calculations and X-ray photoelectron spectroscopy of the electrocatalyst. This process has exceptional performance that can be adapted for a wide range of substrates and is straightforward, ambient, reagent-free, scalable, and therefore beneficial for industrial use. Therefore, initiatives have been taken in this direction.

}, keywords = {C-H activation, Copper, electrochemical oxidation, non-PGM electrocatalysts, tetralin, Tetralone}, issn = {1864-5631}, doi = {10.1002/cssc.202501184}, author = {Cherukuthota, Sri Vidya and Mathew, Elizabeth and Verma, Tushar Singh and Joshi, Krati and Selvaraj, Kaliaperumal} }