Transition Metal Single-Atom Supported on W2n3 as Efficient Electrocatalysts for the Nitrogen Reduction Reaction: A Dft Study

Abstract

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 W2N3 (TM@W2N3) were designed by density functional theory (DFT) for catalytic N2 reduction. The stability, N2 activation capacity, selectivity and NRR mechanism of TM@W2N3 were analyzed. Following the screening process, only 9 TM@W2N3 (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 N2 activation mechanism of V@W2N3, Mo@W2N3 and W@W2N3, as well as the Gibbs free energies of its four NRR reaction pathways were further discussed. The overpotentials (η) of Mo@W2N3 and V@W2N3 to NRR are 0.129 V and 0.470 V, respectively. The overpotential (η) of W@W2N3 is the lowest at 0.059 V, while its catalytic activity is the highest. V@W2N3 and W@W2N3 are more likely to follow the distal pathway for NRR, while Mo 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.

Keywords: Single-atom catalyst, Nitrogen reduction reaction, Density functional theory, Tungsten nitride (W2N3), Supported catalyst