Intermediates Regulation via Electron-Deficient Cu Sites for Selective Nitrate-to-Ammonia Electroreduction

Ammonia (NH3), known as one of the fundamental raw materials for manufacturing commodities such as chemical fertilizers, dyes, ammunitions, pharmaceuticals, and textiles, exhibits a high hydrogen storage capacity of approximate to 17.75%. Electrochemical nitrate reduction (NO3RR) to valuable ammonia at ambient conditions is a promising strategy to facilitate the artificial nitrogen cycle. Herein, copper-doped cobalt selenide nanosheets with selenium vacancies are reported as a robust and highly efficient electrocatalyst for the reduction of nitrate to ammonia, exhibiting a maximum Faradaic efficiency of approximate to 93.5% and an ammonia yield rate of 2360 mu g h-1 cm-2 at -0.60 V versus reversible hydrogen electrode. The in situ spectroscopical and theoretical study demonstrates that the incorporation of Cu dopants and Se vacancies into cobalt selenide efficiently enhances the electron transfer from Cu to Co atoms via the bridging Se atoms, forming the electron-deficient structure at Cu sites to accelerate NO3- dissociation and stabilize the *NO2 intermediates, eventually achieving selective catalysis in the entire NO3RR process to produce ammonia efficiently. Cu/Co0.85SeVSe nanosheets for catalyzing NO3RR are developed by introducing Cu dopants and Se vacancies into Cu0.85Se to efficiently enhance electron transfer from Cu to Co through the bridging Se atoms, leading to the formation of deficient electronic Cu sites that accelerate NO3- dissociation and eventually facilitate the NO3RR process.image