Behavior of bubbles on electrodes with hierarchical microporous structures and different wettability

We have prepared copper electrodes by the hierarchical micropore hydrogen template method. By changing the plating current density and plating time, we can effectively control the size and distribution of the micropores. In addition, we altered the surface chemical composition to obtain electrodes with different wettability. The production and behavior of bubbles on the electrodes with different microstructures and wettability during the process of water electrolysis was investigated. The experimental results indicated that, compared with the hydrophilic porous electrode, the bubbles were able to pin onto the hydrophobic electrode more easily, and they tended to coalesce to form a stable gas film. The effect of the porous structure on the behavior of bubbles was more significant for hydrophilic electrodes than hydrophobic electrodes. The electrodes with hierarchical microporous structures preferred to produce more bubbles than those without microporous structures. The production rate of bubbles on the electrodes with hierarchical microporous structure was faster than that on the electrodes without. Furthermore, porous hydrophilic electrodes with large pore sizes could generate bubbles faster and pin smaller bubbles than electrodes with small pore sizes. We believe that these results can provide theoretical proof for the design of the electrodes with attached micro-bubbles to reduce drag resistance.