Ag/C Cathode Catalyst Fabricated via an Ultrasonic Reduction Method for the Electrolysis of Gaseous Carbon Dioxide

ABSTRACT Highly selective carbon monoxide production can be achieved during the electrolysis of carbon dioxide using a cathode catalyst composed of silver nanoparticles loaded onto a carbon support (Ag/C). Although generating abundant Ag species is desirable for efficient CO 2 electrolysis, conventional methods tend to produce relatively large Ag particles at high loading levels. In this paper, an advanced Ag/C electrocatalyst is produced via ultrasonic reduction (Ag(USR)/C). Importantly, the activity of this electrocatalyst was demonstrated to be superior to those of Ag/C cathodes prepared via conventional methods. This activity was retained under various conditions. In particular, CO was formed during electrolysis when 10 vol.% CO 2 was supplied to the Ag(USR)/C cathode, while only H 2 was evolved on the Periodical Ag/C cathodes. Abundant Ag nanoparticles measuring a few nanometers in diameter were detected on the Ag(USR)/C electrocatalyst surface, whereas significantly larger Ag species were observed on the Periodical Ag/C catalysts. Additionally, electrochemical impedance spectroscopy suggested that electrons were injected into CO 2 more efficiently when the Ag(USR)/C was employed. Accordingly, these small Ag nanoparticles exhibited superior activity in the efficient low‐concentration CO 2 electrolysis and 100% CO 2 electrolysis processes. These results confirm the high CO 2 electrolysis activity of the Ag(USR)/C cathode.