Cascade Electrocatalytic Conversion of CO2 to C3 Products at Elevated Pressures.

Recent progress in the electrochemical reduction of CO2 (CO2RR) has led to notable breakthroughs in generating C2 compounds such as ethylene and ethanol. Nevertheless, the direct formation of C3 products encounters significant limitations due to the C2-C1 coupling reaction, posing a considerable challenge to improving their faradaic efficiency. Here, a design for an elevated pressure cascade catalytic reactor to convert CO2 to C3 products in a two-step electrochemical process is presented. At 25 bar pressure, by regulating the potential of the cascade system and the electrolyte flow rate, a 40% selectivity for 2-propanol on a copper electrode placed upstream of a silver electrode that converts CO2 to CO is reported. In cascade mode (with both silver and copper electrodes active), the C3:C2 oxygenate ratio significantly increases to 7 compared to the noncascade mode (copper only) with a modest ratio of about 0.6. Therefore, our elevated pressure cascade electrolysis approach demonstrates a notable step forward in CO2 electroreduction to oxygenated C3 products.