Boosting Electrocatalytic Nitrate‐to‐Ammonia via Tuning of N‐Intermediate Adsorption on a Zn−Cu Catalyst

Abstract

AbstractThe renewable‐energy‐powered electroreduction of nitrate (NO3−) to ammonia (NH3) has garnered significant interest as an eco‐friendly and promising substitute for the Haber–Bosch process. However, the sluggish kinetics hinders its application at a large scale. Herein, we first calculated the N‐containing species (*NO3 and *NO2) binding energy and the free energy of the hydrogen evolution reaction over Cu with different metal dopants, and it was shown that Zn was a promising candidate. Based on the theoretical study, we designed and synthesized Zn‐doped Cu nanosheets, and the as‐prepared catalysts demonstrated excellent performance in NO3−‐to‐NH3. The maximum Faradaic efficiency (FE) of NH3 could reach 98.4 % with an outstanding yield rate of 5.8 mol g−1 h−1, which is among the best results up to date. The catalyst also had excellent cycling stability. Meanwhile, it also presented a FE exceeding 90 % across a wide potential range and NO3− concentration range. Detailed experimental and theoretical studies revealed that the Zn doping could modulate intermediates adsorption strength, enhance NO2− conversion, change the *NO adsorption configuration to a bridge adsorption, and decrease the energy barrier, leading to the excellent catalytic performance for NO3−‐to‐NH3.