In this talk, Prof Marc Koper Link opens in a new windowjoins us form Leiden University, NL, to discuss the mechanism of the simplest electrocatalytic reaction, namely hydrogen evolution, in both acidic and alkaline media. In addition to the hydrogen binding energy, we show that 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.

This is a departmental lecture for all students and staff. Please come along. Tea, coffee and refreshments will be provided from 10:45 on the Science Concourse outside PLT.