Electroconvective Instability in Water Electrolysis: An Evaluation of Electroconvective Patterns and Their Onset Features

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Abstract

In electrochemical systems, an understanding of the underlying transport processes is required to aid in their better design. This includes knowledge of possible near-electrode convective mixing that can enhance measured currents. Here, for a binary acidic electrolyte in contact with a platinum electrode, we provide evidence of electroconvective instability during electrocatalytic proton reduction. The current-voltage characteristics indicate that electroconvection, visualized with a fluorescent dye, drives current densities larger than the diffusion transport limit. The onset and transition times of the instability do not follow the expected inverse-square dependence on the current density, but, above a bulk-reaction-limited current density, are delayed by the water dissociation reaction, that is, the formation of H+ and OH- ions. The dominant size of the electroconvective patterns is also measured and found to vary with the diffusion length scale, confirming previous predictions on the size of electroconvective vortices.

Original languageEnglish
Article number034021
JournalPhysical review applied
Volume16
Issue number3
DOIs
Publication statusPublished - 10 Sep 2021

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