The impact of anode materials on the performance of electrochemical CO2 reduction to carbon monoxide

Abstract

Electrochemical carbon dioxide reduction reaction (CO2RR) has been investigated for decades. CO2RR to value-added products is an indispensable option to address climate change and energy storage needs. We believed that CO2RR performance can be influenced by the anode materials employed for the oxidation half-reaction. Although H2O oxidation near-neutral solution does not being received greater attention, there is also an idea that it plays an important role not only in completing CO2 reduction cycle, but also to significantly influence the cathode during reduction. Therefore, the present study aimed to investigate the impact of three different anode materials (platinum, glassy carbon, and hematite) on the activity and selectivity of the gold cathode in an electrochemical CO2 reduction reaction. Linear sweep voltammetry and electrochemical impedance spectroscopy have been used to study electrocatalytic properties. In the meantime, x-ray diffraction is used to investigate the crystal planes of the as-prepared electrodes, while the work function and morphology of Au films were measured by atomic force microscope. Similar activity and selectivity to CO formation were observed when platinum and hematite were used as counter electrodes, while the least CO formation was recorded on the glassy carbon counter electrode.Graphic abstractThe protons (H+) obtained from the oxidation of H2O onto these three different anodic materials (platinum, glassy carbon, hematite) are moving faster through the bulk of the solution to the working electrode. Consequently, the reaction occurred on the working electrode can be influenced by the number of protons coming from the anode.