Harnessing Heterogeneous Interface and Oxygen Vacancy in Cu/Cu2O for Efficient Electrocatalytic Nitrate Reduction to Ammonia

In recent years, the electrocatalytic reduction of nitrate to ammonia (NRA) has garnered significant research attention. However, the complex multi-step proton–electron transfer process often results in various by-products, limiting NH3 production. Therefore, designing and developing highly active and selective electrocatalysts for efficient NRA is crucial. This study proposes a method to construct Cu/Cu2O nanosheet arrays with heterogeneous interfaces and oxygen vacancies on copper foam surfaces through electrochemical reduction. The interface coupling between Cu and Cu2O significantly optimizes the catalyst’s surface electronic structure, providing sufficient active sites. In addition, the presence of oxygen vacancies in Cu/Cu2O can optimize the adsorption kinetics of intermediates in the NRA process and effectively inhibit the formation of by-products. The results show that Cu/CuO2 nanosheet arrays are superior NRA catalysts, achieving a Faradaic efficiency of up to 91.1%, a nitrate conversion of 96.25%, and an NH3 yield rate of 6.11 mg h−1 cm−2.