(Invited) Photo-Electrochemical CO2 Reduction on Composite Metal and Metal-Oxide Cathodes

Abstract

Following the first report by Hori et al.1 that demonstrated ability of Group IB (11) based metal cathodes – copper, silver and gold – to promote electro-reduction of CO2 to gaseous products, substantial work has been subsequently devoted to the question of the electrodes deactivation occurring over prolonged electrolysis runs. Although the deactivation affects both an Au and an Ag cathode, where the CO2 reduction leads to the formation of CO, the most severe poisoning occurs in the case of the Cu where production of hydrocarbons (CH4, C2H4) and ethanol is practically suppressed after less than 1 h of electrolysis and become replaced by H2 evolution. SERS measurements conducted during electro-reduction of CO2 on the Cu surface suggest formation of a mixture of copper oxide/hydroxide and carbonate species as being the reason of the observed electrode deactivation. Among the means allowing activation of the cathodes are: short periodic potential cycling, implementation of composite (metal alloy, metal/oxide) electrodes, incorporation into the cathode of plasmonic metal nanostructures. Notably, it was in the case of the roughen silver electrode that the plasmon decay-induced CO2 reduction has been demonstrated for the first time2. 1. Y. Hori, K. Kikushi, S. Suzuki, Chem. Lett. 1695 (1985). 2. J. Augustynski, K. Bienkowski, R. Solarska, Coord. Chem. Rev. (2016).