Oscillating hydrogen bubbles at microelectrodes


Oscillating hydrogen bubbles at microelectrodes

Bashkatov, A.; Yang, X.; Hossain, S. S.; Mutschke, G.; Eckert, K.

Hydrogen produced via water electrolysis, which is powered by renewable energy, is an important energy carrier which may contribute to bridge the storage problem. However, the efficiency of alkaline water electrolyzers is not yet satisfying. Major reasons are the blockage of the active electrode area and the increase the ohmic resistance by the gas bubbles produced.
A deeper understanding of the mechanism of hydrogen bubble evolution therefore may provide additional opportunities to control and enhance the process. Microelectrodes which allow the inspection of single hydrogen bubble evolution are an interesting tool for that purpose [1].
Shadowgraphy and micro-PIV techniques, coupled to measurements of the electric current under potentiostatic mode at a 100 µm Pt electrode led to observation of a novel dynamic phenomenon. This consists in an oscillatory behavior of the hydrogen bubbles at the electrode, which depends on the applied potential and the concentration of the acidic electrolyte. With increasing potential a transition from periodic upward and downward movements of the bubble towards bubble shape oscillations is observed. This phenomenon is connected with the formation of a carpet of a small bubbles at the foot of the growing bubble and includes an oscillatory form of the Marangoni convection recently found on hydrogen bubbles [2]. Two possible candidates for the driving mechanism of the oscillations are discussed.
References:
[1] Yang, Xuegeng, et al. Dynamics of single hydrogen bubbles at a platinum microelectrode. Langmuir 31.29 (2015): 8184-8193.
[2] Yang, Xuegeng, et al. Marangoni convection at electrogenerated hydrogen bubbles. Physical Chemistry Chemical Physics 20.17 (2018): 11542-11548.

Keywords: electrolysis; hydrogen bubble; oscillations; electric force

  • Lecture (Conference)
    90th Annual Meeting of the International Association of Applied Mathematics and Mechanics. The International Association of Applied Mathematics and Mechanics (GAMM e.V.), 18.-22.02.2019, Vienna, Austria

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