In‐situ Reduced Cu3N Nanocrystals Enable High‐Efficiency Ammonia Synthesis and Zinc‐nitrate Batteries

Abstract Nitrate reduction reaction (NO 3 RR) involves an 8‐electron transfer process and competes with the hydrogen evolution reaction process, resulting in lower yields and Faraday efficiency (FE) in the process of NH 3 synthesis. Especially, Cu‐based catalysts (Cu 0 and Cu + ) have been investigated in the field of NO 3 RR due to the energy levels of d ‐orbital and the least unoccupied molecular orbital (LUMO) π * of nitrate's orbital. Based on the above, we synthesized a Cu‐based compound containing Cu 3 N (Cu + ) through a simple one‐step pyrolysis method, applied it to electrocatalytic NO 3 RR, and tested the performance of the Zn‐NO 3 − battery. Through various characterization analyses, Cu‐based catalysts (Cu + ) are the key active sites in reduction reactions, making Cu 3 N a potential catalyst for ammonia synthesis. The research results indicate the application of Cu 3 N catalyst in NO 3 RR shows the best NH 3 yield of 173.7 μmol h −1 cm −2 with FE NH3 reaching 91.0 % at −0.3 V vs . RHE, which is much higher than that of Cu catalyst without N. In addition, the Zn‐NO 3 − battery based on Cu 3 N electrode also exhibits an NH 3 yield of 39.8 μmol h −1 cm −2 63.0 % FE NH3 , and a power density of 2.7 mW cm −2 as well as stable cycling charge‐discharge stability for 5 hours. This work guides the application of Cu 3 N enhanced regulation of the active site in the electrocatalytic synthesis of NH 3 from NO 3 RR.