Screening and Investigation of a Single Transition Metal Atom Dispersed on 2D WS2 as an Effective Electrocatalyst for Nitrogen Fixation: A Computational Study

Recently, the emergence of single-atom catalysts with excellent catalytic performance has brought new vitality to the electrocatalytic nitrogen reduction reaction (NRR). In this work, transition metal (TM) atoms supported on two-dimensional defect free WS2 as electrocatalysts for NRR are systematically explored by first-principles calculations and the computational hydrogen electrode (CHE) model. A three-step strategy is designed to screen a series of non-noble TM atoms (TM = Cr, Mn, Fe, Co, Ni, Ti, V, Zr, Hf, Ta, W, Mo). Our results show that the Mo atom adsorbed on WS2 (Mo@WS2) has the best catalytic performance. The Gibbs free energy diagram reveals that the overpotential is only 0.36 V for Mo@ WS2 as NRR along the enzymatic reaction path. The excellent catalytic performance comes from the charge transfer between Mo@ WS2 and nitrogen molecules. In addition, the preferential adsorption of nitrogen molecules relative to hydrogen atoms on the catalyst effectively inhibits the hydrogen reduction reaction, which proves the selectivity of NRR. The relatively low limiting potential and good selectivity make Mo@WS2 a promising candidate in the field of the NRR electrocatalyst. Our work reveals that isolated TM atoms dispersed on WS2 to form the TMS3 group are conducive to catalyzing NRR.