American Chemical Society, Analytical Chemistry, 24(88), p. 12108-12115, 2016
DOI: 10.1021/acs.analchem.6b02795
Full text: Unavailable
The local electrochemical behavior of a solid−liquid interface can be studied by electrochemical impedancespectroscopy (EIS). The investigated surface area can bedelimited by adding a drop of solution, which forms aninterface between the liquid drop and the working electrode,and performing the measurements inside. The size of the dropmust be sufficiently small for a simultaneous wettabilitycharacterization (from the contact angle measurement) andappropriately large so that wettability is not influenced by thepresence of the working and the counter electrode inserted inthe droplet. In this work, we showed that EIS measurementscan be performed in a solution droplet of 2 to 4 μL, althoughthe electrochemical cell lacks the usual geometry. For ourmeasurements, we studied a model system consisting of a KCl aqueous solution of [Fe(CN)6]3−/4− redox couple at a Ptelectrode. All the results were compared with those obtained for a bulk configuration. The sessile drop configuration and the EISresponse were modeled using finite element method for different electrode sizes and configurations to account forelectrochemical kinetics and both current and potential distributions.