Tandem Routes for Converting Carbon Dioxide to High-Value Hydrocarbons: The Roads to Renewable Chemicals and Fuels

Upgrading CO2 into multicarbon products (C2+) through electrochemical CO2 reduction reaction (eCO2RR) with renewable electricity offers a practical solution to construct a net-zero society. While much progress has been made in the direct eCO2RR, the challenges remain: low CO2 conversion efficiency and selectivity to C2, leading to high energy penalty, with little reporting on C3+, which has higher value-added and energy density, because of complexities of reaction pathways (multistep proton-coupled electron transfer and C–C coupling processes). This perspective provides a comprehensive overview of the tandem pathway including tandem catalysts and tandem systems that can overcome the limitations of direct CO2 electrolysis. We outline the recent advancements categorized by carbon length, from C2 to C4+. While tandem catalysis covers only electrochemical reactions for C2 production, tandem systems address the integration of electrochemical reactions with other reactions, such as thermochemical and biochemical, to expand the range of potential CO2 upgrading products. Then, we present the opportunities and challenges of tandem routes to encourage research in this burgeoning field.