Tuning the N-intermediate adsorption of Cu catalysts for efficient electroreduction of nitrate to ammonia

Abstract

The electrocatalytic nitrate reduction reaction (NO₃RR) is a promising technique for both removal of harmful nitrates 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 mg_cat⁻¹ at −0.7 V vs. reversible hydrogen electrode. Electrochemical in situ characterization reveals that the reaction pathway on Cu/BNHCFs proceeds from *NO to *NH₂OH. Theoretical calculations further indicate that the B, N co-doped carbon support modulates the D-band center of Cu, effectively optimizing the adsorption/desorption processes of key nitrogen-containing intermediates and thus leading 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.