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Efficient reduction of nitrogen to ammonia at a minimal cost would require a recherche catalyst tailored by assimilating the inherent electronic and reactive nature of Single Atom Catalysts (SACs) on heteroatom doped-graphene. A full-scale DFT study accounting for disparate descriptions of atomic orbitals and representation of support, has been carried out to identify the most active and recyclable SAC/B-graphene composite as catalyst for Nitrogen Reduction Reaction (NRR). Dual and Multiphilic descriptors derived reactivity pattern of six different metal SACs V, Fe, Ni, Ru, W and Re on periodic and non-periodic paradigms of pristine and BN-pair doped graphene supports, align with the calculated chemisorption efficacy and activation of N 2 . The enzymatic route of nitrogen reduction on three most ideal metal SACs (V, W and Re) culminates Vanadium SAC, a relatively cheaper metal, anchored on BNring-graphene with an energy barrier of ⩽1.24 eV as a highly active and recyclable catalyst for NRR., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Nanocarbon-based frustrated Lewis pair (FLP) bifunctional catalysts, on account of their unquenched electron transfer property, are becoming increasingly attractive as catalysts for the CO2 reduction reaction via the dissociative chemisorption of H2. In the present study, we propose a nanocarbon-based FLP catalyst. The pair comprises nitrogen doped/phosphorus doped graphene as Lewis bases and M(C6F5)3 (M = B, Al, Ga, and In) as Lewis acids. The computational investigation reveals that the carbon atoms adjacent to the doped N and P atoms are the active sites towards the dissociative chemisorption of hydrogen molecule. The analyses of the Bader charges and difference charge densities validate the dissociative chemisorption of H2 molecule and the fact that a significant electron redistribution promotes the polarization of the hydrogen molecule. Density of states confirms the hybridization between the p-states of the nitrogen/phosphorus atom and the s-state of hydrogen atom in all FLPs. The dissociative chemisorption of hydrogen is noted in all FLP complexes, thereby facilitating a low barrier reaction path for CO2 reduction. Between P-doped and N-doped FLPs, N-doped FLP catalysts prove to be a more promising counterpart with considerably low activation barriers, ranging between 0.01 and 0.11 eV, towards CO2 reduction. Thus, the present study demonstrates the great potential of doped carbon-based FLPs as novel nanostructure catalysts for CO2 reduction via the direct utilization of molecular hydrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • Correlation of catalytic activity to band center and work function. • Al 5 @N 4 -DVG as par to Ru single atom catalyst with ΔG max of 0.78 eV. • Exclusive NRR selectivity on Al 5 @N 4 -DVG electrocatalyst. Density Functional Theory (DFT) investigation on the most earth-abundant Al-based catalysts, has been conducted detailing its electronic properties and catalytic efficacy for nitrogen reduction at ambient condition. The Al-based catalysts have been modulated to perform as par a highly performing, but rare, Ru-single atom catalytic center by varying number of Al atoms, shape, and size. The coalesce of band-center, work function and electronic properties in metal atom catalysts along with N-N bond activation has been demonstrated to be responsible for an efficient nitrogen reduction reaction (NRR) with ΔG max of 0.78 eV in Al 5 supported on N-doped double vacancy graphene (Al 5 @N 4 -DVG) catalyst. Electron localization function analysis has shown a weak physisorption of N 2 in the Al-based catalysts. Projected Density of States (PDOS) illustrates the enhancement of aluminium electron density in Al 5 @N 4 -DVG led to enhanced orbital densities overlap of Al p and N p electrons. The Bader charge analysis and electronic analysis of the intermediates show efficient electron gain on the N atoms, leading to formation of NH 3 from the N x H y intermediates in Al 5 @N 4 -DVG catalyst. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Atom Pair Catalysts (APCs) are computationally evaluated for NRR over HER. • Parameters like limiting potentials, volcano plots with solvent effect studied. • Best electrocatalyst with limiting potential (U L) −0.22 V for combination of Ni–Rh. • AIMD simulations confirms the stability of pair of Ni–Rh electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dinitrogen activation on Al n-1 Li (n = 3–13) nanoclusters with and without support is studied using DFT studies. • Aln-1Li (n = 3–13) nanoclusters showed maximum N-N elongated bond length of 1.4 Å corresponding to redshift of 1207 cm−1 in case of Al 3 Li cluster. • Subsequently, Al n-1 Li (n = 3–13) nanoclusters supported on C 3 defective graphene exhibit enhanced activity in terms of N 2 activation as compared to their bare counter parts. • This study validates why and how increased cluster size is corelated with increased activity and why specific clusters with a particular number of atoms are active when embedded on defective graphene using electronic parameters. • Present work demonstrates maximum N-N elongated bond length of 1.56 Å corresponding to redshift of 1690 cm−1 in case of Al 7 Li@graphene and Al 12 Li@graphene complexes reported till date. Density Functional Theory (DFT) based methods are applied to examine the potential of lithium doped aluminium clusters consisting of 3–13 atoms for dinitrogen molecule activation in terms of N N bond length, redshift in N N bond stretching frequency, nitrogen interaction energy and frontier molecular orbitals analysis. The present work highlights the role of monovacant C 3 defective graphene as a support in fine tuning the catalytic activity of Li doped Al clusters for reduction of N 2. Fundamental insights to synergic binding of clusters with defective graphene is brought out and its role in enhancing activation of dinitrogen molecule is explained. Supported Al n-1 Li clusters with six or more atoms are noted to be more active towards N 2 molecule activation as compared to the clusters without support. Dinitrogen molecule undergoes a maximum bond elongation of 1.56 Å corresponding to redshift of 1690 cm−1 on Al 7 Li@graphene and Al 12 Li@graphene. This is maximum value reported in context of activation for N 2 molecule till date. [ABSTRACT FROM AUTHOR]