Efficient reduction of CO2 to CO over grain boundary rich gold film reconstructed by O2 plasma treatment

Abstract

Electrochemical carbon dioxide reduction offers a potential way to simultaneously mitigate carbon emission and produce value-added carbonaceous fuels and feedstock. This work proposes a facile method of O2 plasma bombardment to obtain efficient Au electrodes for selectively CO2 reduction. A sustainable setup assisted by solar energy is used to realize green utilization of CO2, with Fe2O3 photoanode for voltage compensation and Si solar cell for external bias. The O2 plasma treatment of Au results in formation of grain boundaries via fast surface reconstruction. The Au film with higher density of grain boundary possesses higher electrochemical active surface area, lower surface work function, and faster charge transfer through Au/electrolyte interface, which can facilitate the CO2 reduction. Compared with the as-deposited Au film, the O2 plasma treated Au film displays a lower overpotential and enhanced CO2-to-CO conversion performance. Faradic efficiency of 88.7% towards CO is achieved over plasma treated Au film.