Nitrogen-vacancy-modulated efficient ammonia desorption over 3d TM-anchored BC₃N₂ monolayer

Nitrogen fixation using electrochemical methods on the surface of single-atom catalysts (SACs) provides a highly feasible strategy for green and low-energy-consumption ammonia (NH₃) production. Herein, using density functional theory (DFT) calculations, we explored in detail the potential of monolayer BC₃N₂ SACs supported with 3d transition metal (TM) atoms (TM@BC₃N₂) to facilitate nitrogen reduction. The results revealed that the TM@BC₃N₂ systems exhibited remarkable catalytic activity in the nitrogen-reduction reaction (NRR). The fine NRR activity was related to the just-right bonding/antibonding orbital interactions between the 2π* of N₂ and the d orbitals of the TM ions. The nitrogen-adsorption configurations were found to have different activation mechanisms. In addition, the effects of convectively formed convex nitrogen defects (V_N) on the interaction between N₂ and V_N-TM@BC₃N₂ and the NRR process of V_N-TM@BC₃N₂ were studied, and it was found that V_N could fine-tune the reaction efficiency of the eNRR because after N atom dissociation to form V_N, the interaction of TM-C₃ was enhanced, and the activation of nitrogen and adsorption of NH₃ by the TM-active centers were weakened. The present study can be used as a motivation for further experimental and theoretical research of 2D monolayers as NRR electrocatalysts.