Metal oxides for the electrocatalytic reduction of carbon dioxide: Mechanism of active sites, composites, interface and defect engineering strategies

The electrochemical reduction of CO2 into fine chemicals, assisted with renewable energy, is the most instant approach for balancing the atmospheric CO2 level, as well as for storing solar energy as chemical energy. Due to their easy synthesis and good performance, metal oxides are attractive as electrocatalysts for the CO2 reduction reaction (CO2RR). In this review article, we concise the recent advances in the product efficiency of CO2RR for metal oxide electrocatalysts. It is here worth noticing that, overlooking the metal sites of metal oxide-based catalysts, we only considered the M−O (metal–oxygen bond) active sites for discussion. Further, recent strategies, such as advanced morphologies development and interface and vacancy defect engineering, used to improve the CO2RR performance, are also overviewed. By covering the critical role of catalysts (M−O) structure in efficiency and stability, this review also provides some future aspects for the design and development of efficient metal oxide-based electrocatalysts for CO2RR.