Enhanced Charge Transfer Kinetics for the Electroreduction of Carbon Dioxide on Silver Electrodes Functionalized with Cationic Surfactants

Abstract Cationic ammonium surfactants can be used together with a suitable catalyst to enhance the electroreduction of carbon dioxide (CO 2 RR). However, the underlying reasons for the improvements are not yet well understood. In this study, it is shown that didodecyldimethylammonium bromide (DDAB; [(C 12 H 25 ) 2 N(CH 3 ) 2 ]Br), when added to the catholyte, can increase the rate of CO 2 reduction to CO on silver electrodes by 12‐fold at −0.9 V versus reversible hydrogen electrode. More importantly, electrochemical impedance spectroscopy revealed that DDAB lowers the charge transfer resistance (R CT ) for CO 2 RR on silver, and these changes can be correlated with enhancements in partial current densities of CO. Interestingly, when DDAB is added onto two other CO‐producing metals, namely, zinc and gold, the CO 2 RR charge transfer kinetics are improved only on Zn, but not on Au electrodes. By means of a semiempirical model combining density functional theory calculations and experimental data, it is concluded that DDAB generally strengthens the adsorption energies of the *COOH intermediate, which leads to enhanced CO production on silver and zinc, but not on gold.