An easily prepared NiO@Ni/NiF anode for the efficient electrochemical ammonia oxidation driven by ¹O₂

Under chlorine-free conditions, in order to enhance the performance of electrochemical ammonia oxidation (EAO) and its applicability, a novel NiO@Ni/NiF anode was prepared by simple calcination of commercial Ni foam, which was composed of an outer layer of nickel oxide and an inner layer of Ni⁰. When this anode was used, after 60 min of electrolysis, the degradation rate of 56.66 mg/L NH₄⁺-N was 92%, and the selectivity of N₂ was 90%. Nickel oxide generated from Ni foam after calcination was beneficial for the adsorption and activation of ammonia. Moreover, during the electrolysis process, singlet oxygen generated at the heterojunction anode interface promoted the excellent performance of EAO. When this anode was used to treat goose breeding wastewater (132.3 mg/L NH₄⁺-N and 245.9 mg/L TOC), ammonia removal rate reached 91.9% with 87% N₂ selectivity, and TOC was simultaneously degraded by 92.3%. This study offers a design idea for efficient EAO anode materials and clarifies the ¹O₂-dominated N₂ selectivity oxidation mechanism, providing a theoretical basis for ammonia wastewater treatment.