Modulating Metal-Nitrogen Coupling in Anti-Perovskite Nitride via Cation Doping for Efficient Reduction of Nitrate to Ammonia.

The complexes of metal center and nitrogen ligands are the most representative systems for catalyzing hydrogenation reactions in small molecule conversion. Developing heterogeneous catalysts with similar active metal-nitrogen functional centers, nevertheless, still remains challenging. In this work, we demonstrate that the metal-nitrogen coupling in anti-perovskite Co N can be effective modulated by Cu doping to form Co CuN, leading to strongly promoted hydrogenation process during electrochemical reduction of nitrate (NO RR) to ammonia. The combination of advanced spectroscopic techniques and density functional theory calculations reveal that Cu dopants strengthen the Co-N bond and upshifted the metal d-band towards the Fermi level, promoting the adsorption of NO and *H and facilitating the transition from *NO /*NO to *NO H/*NOH. Consequently, the Co CuN delivers noticeably better NO RR activity than the pristine Co N, with optimal Faradaic efficiency of 97 % and ammonia yield of 455.3 mmol h  cm at -0.3 V vs. RHE. This work provides an effective strategy for developing high-performance heterogeneous catalyst for electrochemical synthesis.