Periodic density functional theory calculations show that a Mn/Re(111) single-atom alloy may be an excellent catalyst with high activity and selectivity for the electrocatalytic N2 reduction reaction.

Transitional metal single atom (TM1) doped graphene catalysts have been widely applied in electrochemical N2 reduction reaction (NRR). However, it remains a challenge for the rational design of highly active and selective electrocatalysts owing to limited knowledge of structure-activity correlations. Here, we adopted first-principle calculations to high-throughput screen the NRR performance of TM1 coordinated with two boron and two nitrogen atoms in graphene (TM1-B2N2/G). A “five-step” strategy was implemented by progressively considering different metrics such as stability, N2 adsorption, N2 activation, potential-determining step, and selectivity. As a result, a volcano plot of reactivity is established by using the valence electron number of TM1 as the descriptor. Among all catalysts, Cr1-B2N2/G exhibits superior performance with a limiting potential of -0.43 V with high selectivity of NRR interpreted by better spatial symmetry and excellent compatibility in terms of energy when N2 interacts with TM1. Our work reveals the general strategy of computational efforts to predict the next generation of advanced catalytic materials for NRR.

Fast selective catalytic reduction of nitrogen oxide with ammonia (NH 3 -SCR) (2NH 3 + NO 2 + NO → 2N 2 + 3H 2 O) has aroused great interest in recent years because it is inherently faster than the standard NH 3 -SCR reaction (4NO + 4NH 3 + O 2 → 4N 2 + 6H 2 O). In the present paper, the mechanism of the fast NH 3 -SCR reaction catalyzed by a series of single-atom catalysts (SACs), M 1 / PTA SACs (PTA = Keggin-type phosphotungstic acid, M = Mn, Fe, Co, Ni, Ru, Rh, Pd, Ir, and Pt), has been systematically studied by means of density functional theory (DFT) calculations. Molecular geometry and electronic structural analysis show that Jahn−Teller distortion effects promote an electron transfer process from N−H bonding orbitals of the NH 3 molecule to the symmetry-allowed d orbitals (d xy and d xd 2 −yd 2 ) of the single metal atom, which effectively weakens the N−H bond of the adsorbed NH 3 molecule. The calculated free energy profiles along the favorable catalytic path show that decomposition of NH 3 to *NH 2 and *H species and decomposition of *NHNOH into N 2 and H 2 O have high free energy barriers in the whole fast NH 3 -SCR path. A good synergistic effect between the Brønsted acid site (surface oxygen atom in the PTA support) and the Lewis acid site (single metal atom) effectively enhances the decomposition of NH 3 to *NH 2 and *H species. M 1 /PTA SACs (M = Ru, Rh, Pd, and Pt)were found to have potential for fast NH 3 -SCR reaction because of the relatively small free energy barrier and strong thermodynamic driving forces. We hope our computational results could provide some new ideas for designing and fabricating fast NH 3 -SCR catalysts with high activity.