Efficient CO and acrolein co-production via paired electrolysis

Paired electrolysis—the combination of a productive cathodic reaction, such as CO2 electroreduction (CO2RR), with selective oxidation on the anode—provides an electrified reaction with maximized atom and energy efficiencies. Unfortunately, direct electro-oxidation reactions typically exhibit limited Faradaic efficiencies (FEs) towards a single product. Here we apply paired electrolysis for acidic CO2RR and the model organic oxidation allyl alcohol oxidation reaction to acrolein. This CO2RR alcohol oxidation reaction system shows (96 ± 1)% FE of CO2 to CO on the cathode and (85 ± 1)% FE of allyl alcohol to acrolein on the anode. As a result of this pairing with organic oxidation on the anode, the full-cell voltage of the system is lowered by 0.7 V compared with the state-of-art acidic CO2-to-CO studies at the same 100 mA cm−2 current density. The acidic cathode avoids carbonate formation and enables a single-pass utilization of CO2 of 84% with a 6× improvement in the atom efficiency of CO2 utilization. Energy consumption analysis suggests that, when producing the same amount of CO, the system reduces energy consumption by an estimated 1.6× compared with the most energy-efficient prior acidic CO2-to-CO ambient-temperature electrolysis systems. The work suggests that paired electrolysis could be a decarbonization technology to contribute to a sustainable future. Paired electrosynthesis is an efficient green process that minimizes resource and energy consumption as well as waste generation. The authors demonstrate an electrolysis system that pairs CO2 reduction to CO at the cathode with allyl alcohol oxidation to acrolein at the anode.