Theoretical Screening of Single-Atom-Embedded MoSSe Nanosheets for Electrocatalytic N₂ Fixation

Abstract

The NH₃ synthesis from N₂ electrochemical reduction under mild conditions is a great challenge. In this study, we investigated a series of transition-metal-embedded MoSSe nanosheets with S or Se vacancy based on the density functional theory calculations. Our results revealed that Mo-embedded MoSSe with S vacancy exhibits the best catalytic performance following the alternating mechanism. The potential-limiting step is the first hydrogenation of the adsorbed N₂ with a barrier of 0.49 eV. The relatively low ΔG of 0.58 eV for NH₃ desorption allows the rapid removal of the products from the catalyst. The high stability of the adsorbed N₂H species implies the great catalytic activity of the Mo-embedded MoSSe. By comparing the adsorption strength between single H atom and N₂ molecule on the active site, the Mo-doped MoSSe possesses a much higher selectivity on nitrogen reduction reaction. Our research may provide insightful ideas for the efficient electrochemical reduction of N₂ to NH₃ in ambient conditions.