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

NH 3 (NH 3 ), known as one of fundamental raw materials for manufacturing commodities such as chemical fertilizers, dyes, ammunitions, pharmaceuticals, and textiles, exhibits a high hydrogen storage capacity of ∼17.75%. Electrochemical nitrate reduction (NO 3 RR) 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 high-efficient electrocatalyst for the reduction of nitrate to ammonia, exhibiting a maximum Faradaic efficiency (FE) of ∼93.5% and an ammonia yield rate of 2360 μg h -1 cm -2 at -0.60 V versus reversible hydrogen electrode (RHE). The in situ spectroscopic and theoretical study demonstrate 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 NO 3 - dissociation and stabilize the *NO 2 intermediates, eventually achieving selective catalysis in the entire NO 3 RR process to produce ammonia efficiently. This article is protected by copyright. All rights reserved.