Voltammetry in low concentration of electrolyte supported by ionic latex suspensions

Abstract

Since ionic conductivity has a linear relation with the square of the number of charge, ionic latex particles with a huge number of the charge could provide high conductance. It is expected that addition of only a small amount of latex particles into voltammetric solution enhances the conductance so much that voltammograms can be measured, overcoming ohmic drop. Conductivity of latex suspensions of polystyrene–polystyrenesulfonic acid with volume fractions less than 0.02, which were well deionized by centrifugation, was determined by ac-impedance at two parallel wire electrodes. Since the resistance was determined by the dependence of the in-phase component on the electrode distance, it did not include participation of electric double layers or adsorption of latex. The relationship between conductivity and a diffusion coefficient stated that the conductivity of the suspension was provided mainly by diffusion of latex particles with multiple charges rather than that of the counterion. The suspension with [H+]=10−5M, corresponding to 8.9×105 number mm−3, including hydrogen gas showed a voltammetric oxidation peak of hydrogen, whereas hydrochloric acid with [HCl]=10−5M showed a resistive current–potential curve.