Au on highly hydrophobic carbon substrate for improved selective CO production from CO2 in gas-phase electrolytic cell

Abstract

Electrochemical conversion of carbon dioxide (CO2) is the most interesting way for the construction of a carbon zero society. Electrochemical reduction of CO2 using lab-made electrolytic cell and gold (Au) electrocatalyst coated on the carbon gas diffusion layer with varying surface properties was investigated on its application to selectively produce CO. Three types or carbon substrates were investigated: superhydrophobic, hydrophobic and hydrophilic substrates. Superhydrophobic carbon substrate exhibited the highest faradaic efficiency (94%) towards CO production and CO/H2 ratio (31.3), under a current density of −8.0 mA/cm2 at a cathode potential of −0.7 V (vs. RHE). As the cathode potential was decreased to −1.3 V (vs. RHE), the faradaic efficiency and CO/H2 ratio of the superhydrophobic substrate both decreased to 77% and 9.6 respectively with a current density of −25 mA/cm2. Despite the decrease, the superhydrophobic substrate still exhibited the best performance owing to the better formation of a three phase interphase at the more hydrophobic electrode. © 2019 Elsevier B.V.