Computational Screening Single-Atom Catalysts Supported on g-CN for N2 Reduction: High Activity and Selectivity

It remains a great challenge to design efficient electrocatalysts for nitrogen reduction reaction (NRR) with high activity and high selectivity. Herein, density functional theory calculations were performed to examine the feasibility of a single transition metal (TM, from Sc to Au) atom supported on a novel graphitic carbon nitride (g-CN) for NRR. It was demonstrated that TM atoms could be anchored on g-CN. With the "acceptance-donation" interaction, the activation of a N-2 molecule was favorably achieved on TM/g-CN. Particularly, five candidates (Nb, Mo, Ta, W, and Re/g-CN) were picked out benefitting from their high NRR activity (limiting potentials of -0.42, -0.39, -0.35, -0.29, and -0.39 V, respectively) and high selectivity (faradic efficiencies of 100, 100, 100, 94, and 69%, respectively). Multiple-level descriptors (Delta G(*N), ICOHP, and phi) shed light on the origin of NRR activity from the view of energy, electronic structure, and basic characteristics. The kinetic stability was validated to ensure the feasibility in real experimental conditions. This work broadens the understanding of single-atom catalysts for N-2 fixation and contributes to the discovery of effective NRR electrocatalysts.