Improving trade-offs in the figures of merit of gas-phase single-pass continuous CO2 electrocatalytic reduction to formate

• Bi-based catalysts were used in a continuous process for CO 2 electroreduction. • The process developed offers the best trade-off among relevant figures of merit. • FE of 90% and concentrations of 340 g·L −1 of HCOO − were achieved. • At 45 mA·cm −2 , energy consumption of only 180 kWh·kmol −1 was required. The electrochemical conversion of CO 2 is gaining increasing attention because it could be considered as an appealing strategy for making value-added products at mild conditions from CO 2 captured. In this work, we report a process for the electrocatalytic reduction of CO 2 to formate (HCOO − ) operating in a continuous way, employing a single pass of the reactants through the electrochemical reactor and using Bi carbon supported nanoparticles in the form of a membrane electrode assembly composed by a Gas Diffusion Electrode, a current collector and a cationic exchange membrane. This contribution presents the best trade-off between HCOO − concentration, Faradaic Efficiency and energy consumption in the literature. We also show noteworthy values of energy consumption required of only 180 kWh·kmol −1 of HCOO − , lower than previous approaches, working at current densities that allow achieving formate concentration higher than 300 g·L −1 and simultaneously, a Faradaic Efficiency close to 90%. The results here displayed make the electrochemical approach closer for future implementation at the industrial scale.