Advancing electrochemical nitrogen reduction: Efficacy of two-dimensional SiP layered structures with single-atom...

Researchers are interested in single-atom catalysts with atomically scattered metals relishing the enhanced electrocatalytic activity for nitrogen reduction and 100 % metal atom utilization. In this paper, we investigated 18 transition metals (TM) spanning 3d to 5d series as efficient nitrogen reduction reaction (NRR) catalysts on defective 2D SiP_V layered structures through first-principles calculation. A systematic screening identified Mo@SiP_V, Nb@SiP_V, Ta@SiP_V and W@SiP_V as superior, demonstrating enhanced ammonia synthesis with significantly lower limiting potentials (-0.25, -0.45, -0.49 and -0.15 V, respectively), compared to the benchmark -0.87 eV for the defective SiP. In addition, the descriptor ΔG_*N was introduced to establish the relationship between the different NRR intermediates, and the volcano plot of the limiting potentials were determined for their potential-determining steps (PDS). Remarkably, the limiting voltage of the NRR possesses a good linear relationship with the active center TM atom Ɛ_d, which is a reliable descriptor for predicting the limiting voltage. Furthermore, we verified the stability (using Ab Initio Molecular Dynamics - AIMD) and high selectivity (U_L(NRR)-U_L(HER) > -0.5 V) of these four catalysts in vacuum and solvent environments. This study systematically demonstrates the strong catalytic potential of 2D TM@SiP_V(TM = Mo, Nb, Ta, W) single-atom catalysts for nitrogen reduction electrocatalysis.