Enhancing electrocatalytic nitrate/nitric oxide reduction to NH3 on two-dimensional p-block InSe monolayer via defect engineering

Abstract

Electrochemical nitrate/nitric oxide (NO3−/NO) reduction to ammonia (NH3) is an environmentally friendly and sustainable strategy that mitigates pollutants while synthesizing value-added products NH3. Despite the prevalence of transition metal-based catalysts, the exploration of inexpensive two-dimensional (2D) p-block materials is needed in NH3 synthesis. Based on density functional theory calculations, we proposed an InSe monolayer with single Se vacancy as an outstanding catalyst for NO3RR and NORR. The catalyst exhibits exceptional catalytic performance, characterized by a low limiting potential comparable to that of most transition metal-based catalysts, and efficaciously suppresses the formation of competitive by-products. Successful adsorption and activation of NO3− and NO molecules are achieved, attributed to the charge rearrangement around the vacancy. The electronic structure analysis reveals that the enhancement of activity stems from the upward shift of the p-band center of unsaturated indium atoms. This work heralds a novel avenue for designing pure 2D p-block NH3 synthesis catalysts and sheds light on a deeper understanding of the catalytic mechanism at the electronic level.