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.