Advances in morphological and interfacial tuning of metal oxides for electrochemical CO2 conversion

The electrochemical CO₂ reduction reaction (CO₂RR) has been recognized as a highly promising technological approach for realizing carbon capture and utilization. A plethora of metal-oxide (MO) nanostructures have been designed with the merits of unique crystal structures to achieve noticeable advances in the electrochemical CO₂RR. However, more efforts are needed to properly elucidate the intricate relationships between their synthesis, structure, and activity. In this perspective, this review centers on: (i) the structural engineering of key factors (e.g., crystal facet, defect, interface, spin, and morphology), (ii) synthesis strategies governing the development of such structural features, (iii) structure–activity relationships, (iv) catalytic mechanisms of multiple proton/electron transfer steps in conversion of CO₂ (e.g., either into C₁ (e.g., CO, CH₄, and CH₃OH) or C₂₊ products (e.g., C₂H₄, C₂H₆, C₂H₅OH, CH₃COOH, and C₃H₇OH)), and (v) the performance metrics of diverse electrocatalysts (e.g., in terms of Faradaic efficiency, current density, and stability). The factors controlling the catalyst morphology and the adsorption/transfer behavior of the key intermediates are also discussed based on in situ/ex-situ techniques combined with density functional theory. Collectively, this review aims to provide critical insights that can guide the rational design of next-generation MO-based electrocatalysts for efficient and selective CO₂ electroreduction.