Nitrogen-vacancy-modulated efficient ammonia desorption over 3d TM-anchored BC 3 N 2 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 (NH 3 ) production. Herein, using density functional theory (DFT) calculations, we explored in detail the potential of monolayer BC 3 N 2 SACs supported with 3d transition metal (TM) atoms (TM@BC 3 N 2 ) to facilitate nitrogen reduction. The results revealed that the TM@BC 3 N 2 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 N 2 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 N 2 and V N -TM@BC 3 N 2 and the NRR process of V N -TM@BC 3 N 2 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-C 3 was enhanced, and the activation of nitrogen and adsorption of NH 3 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.