Generator−Collector Experiments at a Single Electrode: Exploring the General Applicability of This Approach by Comparing the Performance of Surface Immobilized versus Solution Phase Sensing Molecules

Martin C. Henstridge, Gregory Wildgoose, Richard G. Compton

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Abstract

We demonstrate proof-of-concept that generator-collector experiments can be performed at a single macroelectrode and used to determine mechanistic information. The practical advantages of such a system over conventional generator-collector techniques are also outlined. The single-electrode generator-collector technique is applied to study the known mechanism of oxygen reduction in aqueous conditions as a model system. We seek to demonstrate that the single-electrode generator-collector approach is capable of detecting local pH changes, immediately adjacent to the electrode surface during a redox reaction. Experiments are performed using a molecular pH probe attached to the electrode surface. Comparison of experimental data with numerical simulations verifies that the reduction of oxygen at pH 6.8 proceeds via a two-electron, two-proton mechanism. Experiments were also performed with a molecular pH probe dissolved in the electrolyte solution in order to explore the feasibility of this approach, which is potentially applicable to a much wider range of electrochemical systems.
Original languageEnglish
Pages (from-to)1340-1346
Number of pages7
JournalLangmuir
Volume26
Issue number2
DOIs
Publication statusPublished - 19 Jan 2010

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