Multifunctions of carbon dots in the CeO2/Cu2O complex catalyst for the regulation of carbon dioxide reduction

Abstract

For electrocatalytic reactions, charge transfer is a very complex process and also closely related to the chemical reaction process. Herein, taking the CO₂ reduction reaction (CO₂RR) as an example, we report the effect of regulation of CeO₂/Cu₂O-carbon dots (Ce–Cu-CDs) on the CO₂RR, and show the roles of the multifunctions of CDs in this complex catalyst system. The CeO₂/Cu₂O (Ce–Cu) catalyst exhibits the Faraday efficiency (FE) for methane exceeding 50% across a wide potential range (−1.2 V to −1.7 V vs. RHE) in the CO₂RR. The acquired Ce–Cu-CDs catalyst reveals the transformation route of CDs with the ability to store electrons and regulate the CO₂RR process. The electrocatalytic performance test with Ce–Cu-CDs shows that the FE of methane is potential dependent after the addition of CDs. The combination of transient photovoltage, transient potential scanning, density functional theory calculations and in situ infrared spectroscopy has elucidated the multifunctions of CDs in the regulation of route in the CO₂RR, including enhanced charge storage, the weakening of CO₂ activation, the reduction of CO₂ adsorption, the increase of the energy barrier of the rate-determining step of CO₂ conversion to methane, and the reduction of slow electron transfer, thus altering the path of the CO₂RR process. This work unveils the ability of CDs to regulate the pathway of the complex electrocatalytic process and provides a new example for the application of CDs in electrochemical reactions.