Current Measurement and Electrochemical Characterization of Gas Evolution Reactions on a Rotating Ring-Disk Electrode

• Published in: Electrocatalysis Vol. 11; no. 3; pp. 301 - 308
• Main Authors: Bao, Yun, Nagasawa, Kensaku, Kuroda, Yoshiyuki, Mitsushima, Shigenori
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2020; Springer Nature B.V
• Subjects: Bubbles; Catalysis; Chemistry; Chemistry and Materials Science; Electrochemical analysis; Electrochemistry; Electrodes; Electrolysis; Energy Systems; Evaluation; Gas evolution; Hydrogen evolution reactions; Ions; Microscopes; Optimization; Original Research; Physical Chemistry; Rotating disks; Rotation; Water electrolysis; HER; Electrocatalyst activity; OER; RRDE; Bubble behavior
• ISSN: 1868-2529; 1868-5994
• DOI: 10.1007/s12678-020-00589-9

The behavior of bubbles on a rotating ring-disk electrode (RRDE) during water electrolysis has been investigated as fundamental study to evaluate gas evolution reaction electrode activity. The gas evolved on the surface of the electrode reduced the active surface area and increased the overpotential for electrolysis. We investigated how the shape of the electrode affects the bubble behavior and how to obtain an optimal non-blockage electrode surface using a Pt rotating ring disk electrode (RRDE). Standard deviation (SD) of the electrolysis currents was obtained. The value of the SD is corelated with the bubble detachment phenomenon. We found that the rotation induced flux field removes the generated bubble with decrease of the SD. So, a larger SD indicates the bubble accumulation on the electrode surface, and the surface stranding in the gas film. The ring electrode showed higher current with smaller SD than disk electrode at an overpotential for both oxygen and hydrogen evolution reaction. Therefore, a ring electrode is better than a disk electrode to evaluate gas evolution reaction. The optimum current measurement condition is using ring electrode under rotation speed higher than 2500 rpm, because dependence of current and the SD on rotating speed was small enough. Under this condition, HER at − 0.1 V, the ring electrode delivers − 260 mA cm −2 , and the disk delivers − 160 mA cm −2 . For OER at 2.2 V, the ring electrode delivers 195 mA cm −2 , and the disk electrode delivers 130 mA cm −2 . The ring electrode capture about 35% more current than disk, which might be loss by the effect of the bubble blockage. In order to get better current measurement in a gas evolution reaction, using ring electrode to remove the bubbles from the electrode surface in a high rotation speed is recommended. Graphical Abstract