The Role of Adsorbed CN and Cl on an Au Electrode for Electrochemical CO₂ Reduction

Abstract

Electrochemical CO2 reduction is one of the promising ways to convert CO2 to value-added products such as CO. Many studies have dealt with suppressing the hydrogen evolution reaction (HER) and increasing the CO2 reduction reaction (CO2RR) through modification of the metal surface with additives such as anchoring agent, anion, etc. However, there are only a few studies about modifying the Au surface with additives. We present here a theoretical prediction that the addition of the CN and Cl species on an Au electrode would enhance the electrochemical CO2RR due to van der Waals interactions with these large anionic species. On the basis of this suggestion, we then prepared functionalized Au electrodes by electroplating in an aqueous solution containing CN– or Cl– and experimentally verified that the CO2RR of functionalized Au indeed shows exceptional CO2RR activity in comparison to pristine Au.