Abstract:The electrocatalytic carbon dioxide reduction reaction (eCO2RR) powered by renewable energy can convert CO2 into high-value chemicals and fuels. It is a viable solution to address the sharp increase in atmospheric CO2 concentration and global warming. However, in traditional neutral or alkaline electrolytes, eCO2RR suffers from severe carbon loss, resulting in a theoretical single-pass carbon conversion efficiency (SPCE) of less than 50%, and the regeneration of the electrolyte requires additional energy. Acidic electrolytes can effectively solve the carbon loss issue, achieving a theoretical SPCE of 100%, which has attracted widespread attention worldwide. Nevertheless, most previous studies focused on catalyst optimization, with insufficient emphasis on optimizing solid-liquid-gas interfaces such as gas diffusion electrodes (GDEs), electrolytes, and proton membranes. These factors influence the selectivity, stability, and energy efficiency of eCO2RR. In this study, we systematically optimized the three-phase interface (solid, liquid, and gas) of the acidic eCO2RR, achieving a faradaic efficiency for CO (FECO) of over 90% at a current density of 100 mA·cm−2 and a cell voltage of less than 5 V, with stable operation for 110 hours. Finally, we scaled up the electrode area to 100 cm2, exploring the impact mechanism of process scale-up, and proposing a new intermittent operation strategy. This research on interface optimization and process scale-up of acidic eCO2RR is expected to provide a theoretical foundation for its potential industrial applications. Close-