Boosting electrochemical nitrite-ammonia conversion properties by a Cu foam@Cu₂O catalyst

Electrocatalytic reduction of nitrite (NO₂^-) to ammonia (NH₃) can simultaneously achieve wastewater treatment and ammonia production, but it needs efficient catalysts. Herein, Cu₂O particles self-supported on Cu foam with enriched oxygen vacancies are developed to enable selective NO₂^- reduction to NH₃, exhibiting a maximum NH₃ yield rate of 7510.73 μg h^-1 cm^-2 and high faradaic efficiency of 94.21% at -0.6 V in 0.1 M PBS containing 0.1 M NaNO₂. Density functional theory calculations reveal the vital role of oxygen vacancies during the nitrite reduction process, as well as the reaction mechanisms and the potential limiting step involved. This work provides a new avenue to the rational design of Cu-based catalysts for NH₃ electrosynthesis.