Theoretical insights into nonmetal-doped graphyne-supported noble metal electrocatalysts for NH3 synthesis via nitrogen reduction

Abstract

NH3 is a valuable chemical in the agricultural and industrial fields, and a potential carbon-free energy carrier because of its high hydrogen capacity and energy density. Currently, industrial-scale NH3 synthesis is based on the Haber–Bosch process; however, this process consumes large amounts of energy and causes serious pollution. Therefore, new synthetic methods are necessitated for the production of NH3. The electrocatalytic nitrogen reduction reaction (NRR) can be conducted for NH3 production under ambient conditions and is expected to overcome the problems associated with the current processes. Herein, we designed a series of single-atom catalysts for noble metal (NM = Ru, Rh, Pd, Os, Ir, Pt) atoms anchored on non-metallic atom (X = B, N, O)-doped graphyne (NMX@GY) and investigated their effects on NRR performance using density functional theory calculations. It was concluded that RuB@GY and OsB@GY exhibited the highest NRR performance following the distal pathway; they had limiting potentials of −0.458 and −0.323 V and could effectively inhibit competing hydrogen evolution reactions. Furthermore, the high catalytic activity of RuB@GY and OsB@GY was attributed to their electronic structures. This study provides a new strategy for the study of carbon-based electrocatalysts with high activity, selectivity, and stability for NH3 synthesis.