Dynamic determination of Cu+ roles for CO2 reduction on electrochemically stable Cu2O-based nanocubes†
Abstract
Copper (Cu), as the most important and efficient catalyst, has been widely studied for electrochemically reducing carbon dioxide (CO2) into multi-carbon (C2+) products. However, the roles of Cu+ species in CO2 reduction are debatable due to the instabilities of all the reported Cu oxides under negative potentials. Here, for the first time, we fabricated an electrochemically stable Cu2O catalyst. In situ Raman spectroscopy determines that, with the protection of ligands, the Cu+ species are resistant to the negative potentials and remain unchanged during CO2 reduction. We find that stable Cu2O shows a high C2 Faraday efficiency (FE) of 73%, 1.5× higher than that of common Cu2O, which reduces to metallic Cu during the CO2 reduction, suggesting that the Cu+ species promote C–C coupling. Further, we coat the ligand-stabilized Cu2O nanocubes with AgOx clusters, which achieves an increase in ethylene FE from 35% to 50% under a current density of 150 mA cm−2.