@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} }