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.