Coupling denitrification and ammonia synthesis via selective electrochemical reduction of nitric oxide over Fe2O3 nanorods

Abstract

Direct electrochemical conversion of nitric oxide (NO) into ammonia (NH₃) holds great promise for high value-added utilization of industrial gaseous waste and simultaneously mitigating the human-caused imbalance of the global nitrogen cycle. Here, Fe₂O₃ nanorods are proposed as a superb electrocatalyst for the NO reduction reaction to produce NH₃ under ambient conditions. The catalyst achieves a large NH₃ yield of 78.02 μmol h⁻¹ cm⁻² with a fairly high faradaic efficiency of 86.73% in neutral media. Using such a catalyst as the cathodic material, a Zn–NO battery was assembled as an NH₃-producing device with excellent NO conversion efficiency, capable of delivering a power density of 1.18 mW cm⁻² and an NH₃ yield of 145.28 μg h⁻¹ mg_cat.⁻¹. Density functional theory calculations suggest that NO binds to the Fe₂O₃ (104) surface most strongly via electronic state interaction, adopting a charge “acceptance-donation” mechanism and is significantly activated through the 2π* back-donation effect.