Automatic Recording of Differential Capacity Curves for Hanging Drop Electrodes

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Abstract
Development of a rapid automatic method for recording differential capacity curves as a function of potential is discussed. Various electrolytes, electrolyte concentrations, reference electrodes, and frequencies were investigated. The behavior of Teflon as a capillary material for the hanging drop electrode is compared to that of glass and siliconized glass. Moderately good agreement with impedance bridge data is noted. The principal discrepancies between results obtained by the automatic and bridge methods are quantitatively attributed to the area variation. Improvement is found for a platinum-supported drop electrode for which this dependence of area on surface tension is absent. Good agreement with impedance bridge data and electrocapillary data is observed for such electrodes, and the small discrepancies which still remain are consistent with effects, previously observed with hanging drop electrodes, due to the presence of trace amounts of impurities.