Gas phase electrochemical conversion of humidified CO2 to CO and H2 on proton-exchange and alkaline anion-exchange membrane fuel cell reactors

Fuel cell reactors or electrolyzers based on alkaline anion-exchange membrane and proton exchange membrane (AAEM & PEM) are investigated for gas phase electrochemical conversion of humidified CO2 under identical conditions, using conventional Pt/C, Pd/C and Cu/CNTs as cathodic catalysts. Humidified CO2 can be converted to H-2 and CO via the AAEM based fuel cell reactors with an estimated onset potential of - 1.0 V using Cu/CNT as cathodic catalyst, while PEM based fuel cell reactors can only produce H-2 under identical conditions. This can be attributed to the suppressed hydrogen evolution and enhanced CO2 reduction in the case of AAEM based reactor. Remarkably, AAEM based reactor with Cu/CNT cathode catalysts shows a higher activity (8.88 mu mol h(-1) cm(-2)) to convert CO2 to CO than that of Pd/C (7.59 mu mol h(-1) cm(-2)) and Pt/C (0.75 mu mol h(-1) cm(-2)) at the same catalyst loading. This study indicates that AAEM based reactor is able to realize the gas phase electrochemical conversion of CO2, providing a viable strategy for CO2 utilization and conversion to useful fuels.