Applications of a Low Noise Potentiostat in Electrochemical Measurements

Abstract

Measurements on two electrochemical systems, copper in copper sulfate and aluminum in boric acid/tetraborate buffer, have been carried out by recording the amplitude spectrum of the fluctuations in the current density. For these measurements, a low noise potentiostat developed and built at NBS was employed. In the case of copper, the current spectra are found to be the deterministic response of the electrode to the noise voltage generated by the potentiostat. The electrode characteristics for charge-transfer and for diffusion could be obtained from the impedance plots derived from the measurements when the level of the applied signal was of the order of 10-7V. In the case of aluminum, the deterministic response observed in the absence of pitting gave way to random fluctuations in the current in conditions leading to pitting. It is shown that the onset of pit formation can be detected from noise measurements. The significance of the information obtained in electrochemical noise measurements is briefly discussed. * Electrochemical Society Active Member.

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