| Heteropoly oxometallates are attracting considerable attention in electrocatalysis and chemically modified electrodes because of their potential application as catalysts. In this thesis, the preparation of Heteropoly oxometallates and metallic oxide supported heteropoly polymer film modified electrode and their electrochemical and electrocatalytic properties were mainly studied.1. A poly(pyrrole) doped Silicotungstic anion has been prepared by electrochemical polymerisation of pyrrole in aqueous 0.5 mol/L H2SO4 containing SiW12O404-. The experimentation was optimized and electrochemical behaviour of dopamine(DA) on this modified electrode were studied. Including pH effect, initial voltametry quite time and so on. In pH5.0 B-R buffer solution, when the initial voltammetry was controled at -0.3V, the quite time was limited at 10 second,the peak current was directly proportional to the logarithm of concentration for DA over the range of 4.2×10-6～1.1×10-3mol/L, the detection limit is3.2×10-6mol/L.The developed method has been applied to the determination of DA in injection with satisfactory results.2. An aniline(An) doped TiO2-MoO3 supported Silicotungstic acid film modified glassy carbon electrode(PAn/SiW12/TiO2-MoO3/GC) has been prepared by cyclic voltametry. The electrochemical behaviour of ascorbic acid(AA) at this modied electrodes was studied by chronoamperometric and voltammetry. Its diffusion coefficient was 1.88×10-7cm2/s. The oxidation peak currents of AA were linear related to the AA concentration from 5.0×10-5～6.9×10-3 mol/L with correlation coefficient of 0.9961, the detection limit of 1.2×10-6 mol/L of AA was estimated. This method has been successfully applied to the analysis of AA in tomato and orange juice.3. An aniline(An) doped TiO2-MoO3 supported Silicotungstic acid film modified glassy carbon electrode(PAn/SiW12/TiO2-MoO3/GC) has been prepared . Polymerization was optimized,and the electrochemical behaviour of the modified electrode was studied in detail, exhibited good reproducibility and stability,which also showed good catalytic effect on the reduction of nitrite.The possible catalytic process has also proposed.4. An aniline(An) containing TiO2-WO3 supported Silicotungstic heteropolyanion film modified glassy carbon electrode(PAn/SiW12/TiO2-WO3/GC) has been prepared by cyclic voltametry. Polymerization was optimized,and the electrochemical behaviour of the modified electrode was studied in detail, including pH-dependence,stability and so on. Experimental results show that the modified electrode not only maintains the electrochemical activity and electrocatalytic properties of SiW12 ,but also exhibited good reproducibility and stability. In 0.5mol/L H2SO4 solution, the second cathodic peak of SiW12 showed good catalytic effect on the reduction of bromate ,the catalytic process is an EC catalytic mechanism.
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