by Prof. Marc T. M. Koper, Universiteit Leiden (The Netherlands)
In this talk, it will be discussed the mechanism of the simplest electrocatalytic reaction, namely hydrogen evolution, in both acidic and alkaline media. In addition to the hydrogen binding energy, in alkaline media at least two other activity descriptors are relevant: OH or oxygen binding energy of the catalyst surface, and local cation concentration near the electrode surface. Both parameters are expected to influence the rate of the first (Volmer) step in alkaline media. At higher current density, hydrogen evolution becomes dominated by bubble formation and removal. We show that thermal and solutal Marangoni forces due to surface tension gradients in the electrolyte determine the local fluid dynamics and thereby impact bubble coalescence and removal.
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