Tuning the N-Intermediate Adsorption of Cu Catalyst for Efficient Electroreduction of Nitrate to Ammonia

Electrocatalytic nitrate reduction reaction (NO3RR) is a promising technique for both harmful nitrate removal and sustainable NH3 production. As yet, developing an electrocatalyst with high activity and stability remains a significant challenge. Herein, a novel electrocatalyst consisting of Cu nanoparticles dispersed on boron (B) and nitrogen (N) co-doped hollow carbon fibers (Cu/BNHCFs) was successfully fabricated. This was achieved through the stereoselective assembly of a Cu-containing zeolitic imidazolate framework onto electrospun fiber films, followed by pyrolysis. The optimized Cu/BNHCFs catalyst achieves a remarkable Faradaic efficiency of 94.2% for NH3 with a yield rate of 32.35 mg h-1 mgcat-1. Electrochemical in situ characterizations reveal that the reaction pathway on Cu/BNHCFs proceeds from *NO to *NH2OH. Theoretical calculations further indicate that B, N co-doped carbon support modulates the d-band center of Cu, effectively optimizing the adsorption/desorption processes of key nitrogen-containing intermediates to lead to the excellent catalytic performance. This work provides a design strategy for modifying the electronic structure of transition metal catalysts to achieve efficient nitrate reduction to ammonia.