Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The growth of hydrogen bubbles in water electrolysis is of high practical relevance due to the prominent role of hydrogen in the future energy system. The dynamics even of a single bubble is already multifaceted and is associated with several interdisciplinary phenomena such as Marangoni convection [1, 2], bubble-microlayer interaction [3, 4] and electric forces on the bubbles [4,5].

In this contribution, the dynamics of a single hydrogen bubble was studied during water electrolysis at a horizontal Pt microelectrode in an acidic environment. A new phenomenon was observed. It consists of the ability of already detached hydrogen bubbles, expected to continue buoyant rise, to reverse the direction of motion and to return to the electrode from relatively large distances (350 μm). The phenomenon was systematically studied at different cathodic potentials and electrolyte concentrations by using high-speed microscopic shadowgraphy and electric current measurements.

Acknowledgment
This project is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economics and Technology (BMWi) due to the enactment of the German Bundestag under Grant No. DLR 50WM2058 (project MADAGAS II).