CO2 reduction to multicarbon products: From catalyst design to electrode engineering

The electrochemical CO 2 reduction reaction (CO 2 RR) has emerged as a promising technology for converting renewable electricity and captured carbon dioxide into valuable chemicals and fuels. Among the various products generated from CO 2 RR, multicarbon (C 2+ ) products, including ethylene, ethanol, and propanol, are particularly attractive because of their high market value and broad industrial applications. Over the past decade, significant progress has been achieved in catalyst development, especially for copper-based materials that can facilitate carbon–carbon (C–C) coupling. As a result, Faradaic efficiencies exceeding 50% and current densities above 200 mA cm −2 have been reported in advanced systems. However, recent studies have demonstrated that catalyst optimization alone is insufficient to achieve commercial implementation. Challenges associated with mass transport, carbon utilization, water management, membrane stability, and product separation have become increasingly important as CO 2 electrolysis moves from laboratory-scale H-cells or flow cells to industrially relevant membrane-electrode assembly (MEA) electrolyzers. This review summarizes recent advances in catalyst design, mechanistic understanding, electrode engineering, membrane technologies, and reactor architectures for C 2+ production. Particular attention is given to the transition from catalyst-centered research to integrated electrolyzer design. Finally, the remaining challenges and future opportunities for practical CO 2 -to-C 2+ conversion are discussed.