A silver–copper oxide catalyst for acetate electrosynthesis from carbon monoxide

Acetic acid is an important chemical feedstock. The electrocatalytic synthesis of acetic acid from CO2 offers a low-carbon alternative to traditional synthetic routes, but the direct reduction from CO2 comes with a CO2 crossover energy penalty. CO electroreduction bypasses this, which motivates the interest in a cascade synthesis approach of CO2 to CO followed by CO to acetic acid. Here we report a catalyst design strategy in which off-target intermediates (such as ethylene and ethanol) in the reduction of CO to acetate are destabilized. On the optimized Ag–CuO2 catalyst, this destabilization of off-target intermediates leads to an acetate Faradaic efficiency of 70% at 200 mA cm−2. We demonstrate 18 hours of stable operation in a membrane electrode assembly; the system produced 5 wt% acetate at 100 mA cm−2 and a full-cell energy efficiency of 25%, a twofold improvement on the highest energy-efficient electrosynthesis in prior reports. The direct electrosynthesis of acetic acid from CO2 typically has the drawback of CO2 crossover. Now, a cascade approach for the electroreduction of CO2 to CO, followed by CO to acetic acid, is reported in which off-target intermediates are destabilized, leading to an acetic acid Faradaic efficiency of 70%.