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

Graphical Cu-based compound containing Cu 3 N is synthesized through a simple one-step pyrolysis method, applied it to electrocatalytic NO 3 RR, and tested the performance of the Zn-NO 3 − battery. The Cu 3 N exhibits NH 3 yield of 173.7 μmol h −1 cm −2 , with FE NH3 reaching 91.0 % at −0.3 V vs . RHE, which assembles a Zn-NO 3 − battery. 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.