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.