Surface-Morphology-Dependent Electrolyte Effects on Gold-Catalyzed Electrochemical CO 2 Reduction

The electrocatalytic property of a flat or an oxide-derived nanostructure Au electrode was investigated using surface sensitive analysis methods such as impedance spectroscopy and Kelvin probe force microscopy (KPFM) when electrochemical conversion of carbon dioxide (CO 2 ) to carbon monoxide (CO) was performed with either KHCO 3 - or NaHCO 3 -based neutral electrolyte. A strong dependence on the cation of the electrolyte was exhibited on the flat Au electrode surface. CO selectivity and capacitance dispersion are significantly higher with the KHCO 3 electrolyte. On the other hand, the nanostructured Au electrodes, having much more improved activity and durability of CO 2 reduction, showed much less electrolyte-dependent catalytic activity. The difference in CO selectivity with KHCO 3 and NaHCO 3 electrolytes can be explained by the difference in hydration level and consequent adsorption…