Engineering a dual-site CuO/Cu 2 O/CeO 2 heterostructure: synergistic Cu + /Cu 2+ and CeO 2 modulation for tandem ammonia electrosynthesis from nitrate

Abstract

The electrochemical nitrate reduction reaction (eNO3RR) offers a sustainable strategy for ammonia (NH3) synthesis while simultaneously addressing nitrate pollution. However, its reaction kinetics and selectivity remain constrained, especially on Cu-based electrocatalysts, owing to the premature desorption of the nitrite intermediate (*NO2), which undermines both the NH3 production rate and Faradaic efficiency (FE). In this work, a CuO/Cu2O/CeO2 heterostructure is fabricated on nickel foam via in-situ growth and subsequent calcination. By precisely tuning the calcination temperature, the Cu 2+ /Cu + ratio is effectively modulated. The incorporation of CeO2 induces abundant oxygen vacancies and Lewis acid sites, which cooperatively stabilize Cu δ+ (1<δ<2)