Surface Structure Sensitivity of CO₂ Electroreduction on Low‐Index Gold Single Crystal Electrodes in Ionic Liquids

Abstract

Golden contest: CO2 electroreduction in room-temperature ionic liquids is highly sensitive towards the gold electrode surface structure. An Au(110) surface is by far the most active among low-index Au(hkl) facets irrespective of the chemical nature of the IL used as the electrolyte.The activity of low-index Au(hkl) single crystal electrodes towards CO2 electroreduction (CO2RR) was examined for eight room temperature ionic liquids (ILs) by means of cyclic voltammetry. We demonstrate that CO2RR is highly sensitive towards the electrode surface structure, with the Au(110) surface being by far the most active irrespective of the chemical nature of the IL used as electrolyte. The activity of all three low-index Au(hkl) surfaces towards CO2RR decreases upon multiple potential cycling. In situ scanning tunneling microscopy indicates that this deactivation is related to massive Au surface restructuring processes taking place in ILs due to the potential–induced reconstruction and lifting of the surface reconstruction. Additionally, the Au(111) surface undergoes severe etching at the potentials of CO2RR, whereas we do not observe this etching process for Au(110). As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.