Influence of Gas- Porous Electrode- Electrolyte Interfacial Properties on Electrochemically Generated Bubbles

Electrochemical Gas Evolution Reactions (GERs) such as hydrogen and oxygen evolution are vital for clean energy generation. Micro/nanostructured electrodes, especially superaerophobic ones, can enhance GER efficiency by altering bubble adhesion behaviour. The balance between interfacial buoyancy and adhesive forces acting on a generated bubble significantly impacts bubble behavior and, consequently, reaction efficiency. This study investigates the influence of gas-electrode-electrolyte interfacial characteristics of a hierarchical porous electrode on bubble detachment behavior. A two-step experimental approach is employed. The first step involves fabricating Cu electrodes with varying macro- and microscale porosities using the DHBT method while the second step entails high-speed visualization of in-situ gas evolution in an acidic environment. High-speed visualizations of evolving gas bubbles are used to quantify key properties, including mean detached diameter and number density distribution. Electrodes with larger pore height and size are observed to produce larger bubble sizes and lower number densities, likely due to bubble coalescence along the pore length. This research may provide insights into designing electrodes that can effectively minimize bubble adhesion and improve the overall performance of GERs.