Accelerating Industrial‐Level NO3− Electroreduction to Ammonia on Cu Grain Boundary Sites via Heteroatom Doping Strategy

Abstract Although the electrocatalytic nitrate reduction reaction (NO 3 − RR) is an attractive NH 3 synthesis route, it suffers from low yield due to the lack of efficient catalysts. Here, this work reports a novel grain boundary (GB)‐rich Sn‐Cu catalyst, derived from in situ electroreduction of Sn‐doped CuO nanoflower, for effectively electrochemical converting NO 3 − to NH 3 . The optimized Sn 1% ‐Cu electrode achieves a high NH 3 yield rate of 1.98 mmol h −1 cm −2 with an industrial‐level current density of −425 mA cm −2 at −0.55 V versus a reversible hydrogen electrode (RHE) and a maximum Faradaic efficiency of 98.2% at −0.51 V versus RHE, outperforming the pure Cu electrode. In situ Raman and attenuated total reflection Fourier transform infrared spectroscopies reveal the reaction pathway of NO 3 − RR to NH 3 by monitoring the adsorption property of reaction intermediates. Density functional theory calculations clarify that the high‐density GB active sites and the competitive hydrogen evolution reaction (HER) suppression induced by Sn doping synergistically promote highly active and selective NH 3 synthesis from NO 3 − RR. This work paves an avenue for efficient NH 3 synthesis over Cu catalyst by in situ reconstruction of GB sites with heteroatom doping.