Electroactive layers impedance measurements

As the frequency of voltage perturbation is increased, one may limit the penetration depth (D/jco) of a concentration wave generated by the redox reaction so that it is much smaller than the thickness of the electroactive polymer film. In this region, one measures the kinetics of the charge injection process at the surface (Region III). The impedance characteristic is a semicircle in the Zreal vs —Zjmag impedance plane plot. For the impedance measurement, one may obtain Rct, the charge transfer resistance, and the double layer capacitance Cdl- This procedure was used to calculate the... 

First, we consider the properties of a microelectrode in contact with a solution of pure electrolyte in the absence of a dissolved or immobilized redox active analyte. The objective is to understand the fundamental behavior of microelectrodes in the absence of an electroactive analyte and to discuss strategies for optimizing the electrode s temporal response. The existence of the double-layer capacitance (see Chapter 1) at the working electrode complicates electrochemical measurements at short timescales. Figure 6.1.1.1 is an equivalent circuit of an electrochemical cell where Zp is the faradaic impedance corresponding to the... 

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