Nafion-Coated Mercury Thin Film and Glassy Carbon Electrodes for Electroanalysis: Characterization by Electrochemical Impedance

The different behavior of Nafion-coated mercury thin-film electrodes in anodic stripping voltammetry in nitrate and acetate buffer electrolytes has been probed by electrochemical impedance studies. Investigations concerned glassy carbon electrodes, glassy carbon coated with Nafion, mercury thin film electrodes and mercury thin film electrodes deposited between the glassy carbon substrate and the polymer film, with values of applied potential similar to those employed in anodic stripping voltammetry. Comparison is made with results obtained using Nafion/5 % poly(vinyl sulfonic acid) coatings. In the absence of cationic reducible species, acetate buffer leads to larger impedance values than nitrate electrolyte and correlates well with better characteristics of stripping signals at Nafion-based coatings on mercury thin-film electrodes.