Electrochemical reduction of CO2 towards multi-carbon products via a two-step process

The electrochemical conversion of carbon dioxide (CO2) towards clean fuels and chemicals powered by renewable energy is a promising strategy to realize the closing of the loop of carbon footprint. However, the direct reduction of CO2 to multi-carbon (C2+) products suffers from low activity in non-alkaline electrolyte or electrolyte degradation problem caused by carbonate formation in alkaline electrolyte. The two-step process for CO2 electrocution can circumvent such problems by converting CO2 to CO (the first step) in the non-alkaline electrolyte and promote the rate of carbon–carbon coupling for CO-to-C2+ conversion (the second step) in alkaline electrolytes. We summarize the recent progress of CO-selective catalysts, C2+-selective catalysts, tandem catalysts, and tandem reaction systems, which aim to achieve the efficient production of C2+ products with high selectivity. The two-step route of CO2 reduction pushes the chemical production from environmentally abundant molecules closer to the practical application, offering a promising replacement in the petrochemical industry for chemical production under hydrogen economy in the future.