Creating Moderate Local Reaction Environment on Nanoporous Cu ₂ O for Electrocatalytic Ammonia Oxidation to Nitrite and Nitrate

Abstract Electrochemical ammonia oxidation reaction (AOR) presents a promising strategy for sustainable nitrite and nitrate (NO _x ⁻ ) production. Conventional noble metal‐based AOR catalysts often yield undesired dinitrogen and suffer from AOR intermediates poisoning. Herein, nanoporous Cu ₂ O (np–Cu ₂ O) prepared by dealloying plus annealing is reported as an efficient AOR electrocatalyst for NO _x ⁻ production. The np–Cu ₂ O undergoes structural reconstruction during AOR to form the Cu ₂ O/CuO heterostructure with moderate Lewis acidity, which optimizes the *NH ₂ adsorption and improves the interface water structure to regulate the local OH ⁻ distribution, significantly reducing the energy barrier for AOR. Consequently, the np–Cu ₂ O exhibits a total NO _x ⁻ yield rate of 134.62 µmol cm ⁻² h ⁻¹ with a high total Faradaic efficiency of 90.8%. Additionally, efficient and stable NO _x ⁻ synthesis is achieved in an electrolyzer coupled with AOR and oxygen reduction reaction (ORR), which delivers an onset potential of ≈0.5 V and a high NO _x ⁻ Faradaic efficiency of 94.6% at 10 mA cm ⁻² . This work would shed light on the design of high‐efficiency electrocatalysts via Lewis acidity regulation for the efficient NO _x ⁻ production by AOR.