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

Abstract

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 (VN) on the interaction between N2 and VN-TM@BC3N2 and the NRR process of VN-TM@BC3N2 were studied, and it was found that VN could fine-tune the reaction efficiency of the eNRR because after N atom dissociation to form VN, 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.