Electrocatalytic Reduction of Gaseous CO2 to CO on Sn/Cu-Nanofiber-Based Gas Diffusion Electrodes

Earth-abundant Sn/Cu catalysts are highly selective for the electrocatalytic reduction of CO2 to CO in aqueous electrolytes. However, CO2 mass transport limitations, resulting from the low solubility of CO2 in water, so far limit the CO partial current density for Sn/Cu catalysts to about 10 mA cm(-2). Here, a freestanding gas diffusion electrode design based on Sn-decorated Cu-coated electrospun polyvinylidene fluoride nanofibers is demonstrated. The use of gaseous CO2 as a feedstock alleviates mass transport limitations, resulting in high CO partial current densities above 100 mA cm(-2), while maintaining high CO faradaic efficiencies above 80%. These results represent an important step toward an economically viable pathway to CO2 reduction.