Transition metal single-atom supported on W2N3 as efficient electrocatalysts for the nitrogen reduction reaction: A DFT study.

The problems of poor Faraday efficiency and high overpotential usually limit electrochemical nitrogen reduction (NRR) catalysts. In this paper, 28 different transition metal single-atoms (TM-SAs) supported on W 2 N 3 (TM@W 2 N 3) were designed by density functional theory (DFT) for catalytic N 2 reduction. The stability, N 2 activation capacity, selectivity and NRR mechanism of TM@W 2 N 3 were analyzed. Following the screening process, only 9 TM@W 2 N 3 (TM=Sc, Ti, V, Co, Cu, Y, Mo, Ag, W) structures were identified as exhibiting high stability, strong activation capacity and high NRR selectivity. And then N 2 activation mechanism of V@W 2 N 3 , Mo@W 2 N 3 and W@W 2 N 3 , as well as the Gibbs free energies of its four NRR reaction pathways were further discussed. The overpotentials (η) of Mo@W 2 N 3 and V@W 2 N 3 to NRR are 0.129 V and 0.470 V, respectively. The overpotential (η) of W@W 2 N 3 is the lowest at 0.059 V, while its catalytic activity is the highest. V@W 2 N 3 and W@W 2 N 3 are more likely to follow the distal pathway for NRR, while Mo@W 2 N 3 is more likely to follow the enzymatic pathway. This study offers some theoretical foundation and reference for the design of new and efficient electrocatalytic NRR catalysts. [Display omitted] • 28 transition metal supported on W 2 N 3 (TM@W 2 N 3) were designed by DFT for NRR. • Analyzed TM@W 2 N 3 : stability, N 2 activation capacity, selectivity and NRR mechanism. • N 2 activation mechanism of V@W 2 N 3 , Mo@W 2 N 3 and W@W 2 N 3 for NRR pathways were discussed. • V@W 2 N 3 and W@W 2 N 3 follow the distal pathway, Mo@W 2 N 3 follows the enzymatic pathway. • W@W 2 N 3 exhibits the lowest overpotential (η=0.059 V) and the highest catalytic activity. [ABSTRACT FROM AUTHOR]