In Situ Monitoring And Studies On Several Chemical/Electrochemical Oscillatory Systems By EQCM And Spectroelectrochemistry

Intensive investigations on chemical/electrochemical oscillations are helpful for understanding more on the nonequilibrium/nonlinear problems being ubiquitous in many natural science fields, including some periodic phenomena in life sciences, thus they are always receiving wide and great attentions and very active for years.Electrochemical quartz crystal microbalance (EQCM), which can respond real time to the electrode mass change down to the nanogram level, to the solution viscosity/density, and to the viscoelasticity of a foreign film loading on the electrode, has become a very popular analytical tool in electrochemistry and electroanalytical chemistry. Spectroelectrochemistry (SEC) as a combination of electrochemistry with spectroscopy can provide highly specific information on the electrode process at the molecular/atomic level, and it has been widely recognized as one of the most exciting achievements in electrochemistry and electroanalytical chemistry. However, it seems that the applications of EQCM and SEC to the studies of chemical/electrochemical oscillations are rather limited in literatures to date, though a wealthy of real time information can be acquired from the two methods and their combination, from which the applications of the present methods may be extended more intensively to the nonlinear problems. The studies in this thesis are summarized as follows: 1. The development and recent progress of chemical/electrochemical oscillations, spectroelectrochemistry (SEC), and electrochemical quartz crystalmicrobalance (EQCM) are briefly reviewed.2.The electrochemical quartz crystal impedance system (EQCIS) and UV-Vis reflectance spectroelectrochemistry have been employed to study the potential oscillation during the galvanostatic reduction of Fe(CN)63" on the Au electrode in 1 mol L"1 NaOH aqueous solutions. During the potential oscillation, at the low potential, the continuous congregation of bubbles on the electrode surface, and at the high potential, the continuous supplement of Fe(CN)63" due to continuous stirring of solution during the bubbles evolution from the solution are concluded. The effect of generation behavior of bubble in 1 mol L"1 NaOH aqueous solution on the resonant frequency, motional resistance, and half-peak width of the electroacoustic conductance spectrum of EQCIS are reported.3.Galvanostatic oxidation of glucose, galactose and ethanol at platinum electrodes in 0.5 mol L"1 aqueous NaOH and accompanying potential oscillation behaviors were comparatively studied by the electrochemical quartz crystal microbalance (EQCM) method. The EQCM-frequency oscillation was synchronously observed for the two saccharide systems during their potential oscillations, but it was negligibly small for the ethanol system, and the responses of the motional resistance were minor for all systems, suggesting that the mass effect governed the EQCM frequency responses. Although glucose and galactose are very similar in chemical structure and the amplitude for potential or frequency oscillation was roughly equivalent for...