In‐situ reduced Cu3N nanocrystals enable high‐efficiency ammonia synthesis and zinc‐nitrate batteries

Nitrate reduction reaction (NO3RR) 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 NH3 synthesis. Especially, Cu‐based catalysts (Cu0 and Cu+) have been investigated in the field of NO3RR 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 Cu3N (Cu+) through a simple one‐step pyrolysis method, applied it to electrocatalytic NO3RR, and tested the performance of the Zn‐NO3− battery. Through various characterization analyses, Cu‐based catalysts (Cu+) are the key active sites in reduction reactions, making Cu3N a potential catalyst for ammonia synthesis. The research results indicate the application of Cu3N catalyst in NO3RR shows the best NH3 yield of 173.7 μmol h−1 cm−2, with FENH3 reaching 91.0% at −0.3 V vs. RHE, which is much higher than that of Cu catalyst without N. In addition, the Zn‐NO3− battery based on Cu3N electrode also exhibits an NH3 yield of 39.8 μmol h−1 cm−2, 63.0% FENH3, and a power density of 2.7 mW cm−2, as well as stable cycling charge‐discharge stability for 5 hours.