Rotating ring-disc electrode method: Assessing transient chemical interaction of redox intermediate with electrode surface

The interaction of redox intermediate with electrode surface is a seldom explored realm yet an interesting facet in electrocatalysis. This work demonstrates, for the first time, the analytical use of rotating ring-disc electrode to measure the intermediate-electrode interaction in a double-layer model. Our solution to the electro-kinetics reveals the intrinsic dependence of the collection efficiency on the extent of intermediate-electrode interaction, as validated by two redox couples typical of 'outer-sphere' (Fe(CN)63–/Fe(CN)64–) and 'inner-sphere' (dopamine/ dopaminoquinone) nature on Pt and Au electrodes. The experiment with the model systems validates the applicability of the theory, allowing semi-quantitative comparison of the transient binding with different electrode surfaces, while the limitations of the method are also discussed at insightful depth. As a proxy to better understand redox intermediates, the method is set to provide a practical tool and an inspiration to expand the analytical toolset for materials research.