Synergism of Interfaces and Defects: Cu/Oxygen Vacancy-Rich Cu-Mn3O4 Heterostructured Ultrathin Nanosheet Arrays for Selective Nitrate Electroreduction to Ammonia

Achieving high efficiency in nitrate (NO3–) to ammonia (NH3) electrocatalysis requires the exploration of advanced electrocatalysts with a well-designed composition and architecture. In this work, a facile one-step hydrothermal approach was developed for the construction of novel Cu/oxygen vacancy-rich Cu-Mn3O4 heterostructured ultrathin nanosheet arrays on Cu foam (Cu/Cu-Mn3O4 NSAs/CF). Two-dimensional ultrathin nanosheet arrays could increase the exposure of catalytically active centers, and the heterogeneous nanointerface and oxygen vacancies synergistically improve the nitrate-to-ammonia activity over the active centers. Due to the desirable compositional and structural advantages, the Cu/Cu-Mn3O4 NSAs/CF demonstrated excellent performance for the electrocatalytic nitrate reduction to ammonia with high ammonia selectivity (87.6%) and Faradic efficiency (92.4%).