Electrochemical CO2 reduction using alkaline membrane electrode assembly on various metal electrodes

Abstract Electrochemical CO 2 reduction reaction (CO 2 RR) has received much attention as a promising technology to reduce CO 2 using renewable electricity, but it typically suffers from low CO 2 solubility in aqueous phase and a high cell resistance of a conventional liquid phase reactor. Here, we report the CO 2 RR using a membrane electrode assembly that consists of gas diffusion electrode (GDE) and anion exchange membrane (AEM). The GDE enabled facile mass transfer of gaseous CO 2 directly to the catalyst and the AEM could suppress hydrogen evolution reaction (HER) by increasing local pH at the catalyst. Various metal powders of Pd, Ag, Zn, Cu, Sn, Ru, Pt, Ni were tested as cathode catalysts. Pd and Ag showed high current density of >200 mA cm −2 at -3.0 V and faradaic efficiency >95% for CO production with a low cell resistance of 2 flow rate, and it was comparable to the values obtained from gas-phase CO 2 reduction.