Bubble size distribution and electrode coverage at porous nickel electrodes in a novel 3-electrode flow cell

A novel 3-electrode cell type is introduced to run parametrical studies of H2 evolution in an alkaline electrolyte on porous electrodes. Electrochemical methods combined with a highspeed optical measurement system are applied simultaneously to characterize the electrodes and the bubble dynamics in terms of bubble size distribution and coverage of the working electrode. Three different cathodes made of expanded nickel are investigated at applied current densities of |j| = 10-200 mA cm-2 without forced flow and at a flow rate of 5 ml min-1. The applied current density is found to significantly influence both the size of detached bubbles and the surface coverage of the working electrode. The forced flow through the cathodes is found to strongly reduce the bubble size up to current densities of about 100 mA cm-2, whereas the initial transient until the cathode surface is completely covered by bubbles is only marginally affected by the flow-through. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A novel 3-electrode cell is used to investigate H2 evolution on porous electrodes in an alkaline electrolyte. Electrochemical methods and high-speed optical measurement are applied to characterize the electrodes and bubble dynamics. The size of detached bubbles and the surface coverage of the electrode are significantly influenced by the applied current density. Forced flow reduces the bubble size, while the initial transient is less affected by flow-through.