Application of quartz crystal microbalance technique to electrochemical reaction at the interfaces of noble metal (Pt, Au) / aqueous solution, active metal (Fe) / aqueous solution and $MnO_2$ / aqueous solution

Abstract

The present work is concerned with the electrochemical characterization of hydrogen and sulfate ions adsorption on the noble metals (Pt, Au), breakdown of passivity in the active metal (Fe), and redox reactions of a cathode material for alkaline battery ($MnO_2$) by using the in-situ quartz crystal microbalance (QCM) technique combined with other electrochemical ones such as cyclic voltammetry (CV), potentiodynamic polarization and potentiostatic current transient techniques. In chapter III, the adsorption of hydrogen and (bi-)sulfate ions on the platinum and gold electrodes in sulfuric acid solution has been investigated by using QCM technique combined with CV. In the case of platinum electrode, the derivative of the cyclic gravimetrical data showed that two peaks related with hydrogen desorption had the same peak height at the potentials of -0.1 and 0 $V_{SCE}$. By contrast, the second peak was about two-thirds of the first peak in the cyclic voltammogram. From these results, it was suggested that the adsorption of the (bi-)sulfate ion began at about the potential between the two potentials concerning hydrogen desorption peaks. The results in this work were discussed in comparison with those from radio tracer data and FTIR data by other researchers with respect to the adsorption of the (bi-)sulfate ion. In the case of gold electrode, the derivative of the cyclic gravimetrical data exhibited several peaks appearing in the zero charge potential region of -0.15 to 0.35 $V_{SCE}$. These peaks may be related to the specific adsorption of the (bi-)sulfate ions on the each crystal faces of the poly-crystalline gold electrode. The mass change results were also discussed in comparison with those from AES in relation to the hydrogen bonded water dipole and adsorbed (bi-)sulfate ion. In chapter Ⅳ, the breakdown of passivity of the Fe thin film in the chloride-containing solution has been investigated by using QCM technique combined with potentiodynamic polarization...