In situ videometry monitoring of bubble behavior during the electrocatalytic oxygen evolution reaction

Abstract

Cyclic voltammetry (CV) on rotating Pt disc electrode was used for electrocatalytic oxidation of OH-. Hydroxide ion oxidation is followed by oxygen evolution with gas bubble formation. The image analysis was performed in situ in order to find correlation between bubbles related phenomena and the current of OH- oxidation. Bubble formation was tested in four different regimes having different scan rate and/or electrode rotation rate. The videometry using high speed camera was applied to observe the bubble related phenomena. The integral effect of presence of bubbles was analyzed. The fast Fourier transformation and normalized power spectra were used for advanced image analysis. Using this type of analysis, two different characteristic periodical behaviors were reported for the first time. The obtained periods were in accordance with scan rate and electrode rotation rate. The former periodic component of bubble formation process was correlated with well defined CV cycles, and hence, related to electrocatalytic oxidation-reduction of OH-. The other periodic component of bubble behavior induced by rotation rate (600 rpm) was shifted from 0.01 s toward slightly higher values probably due to hydrodynamic conditions in the investigated system.