The Preparation And Electrocatalysis Of Conducting Polymer Film Modified Electrode

Polymer films of Hemin and Vitamin B and dyes were obtained at a graphite carbon electrode and glass carbon by a cyclic voltammetry in aqueous solution. Both the electropolymerization process of these compound and electrochemical behavior of the modified films were studied by cyclic voltammetric method and potential step chrono-amperometry in this work. The electrocatalytic oxidation of epinephrine (Ep). dopamine (DA), cysteine, ascorbic acid and the electrocatalytic reduction for oxygen and nitrite were also investigated.After modification on graphite carbon electrode, Cyclic voltammograms of the film of Hemin electrode in 0.1 mol-L-1 NaOH exhibited two pair stable and reversible redox waves with peak formal potential at -0.730V and 0.530V respectively. For thicker films(the modified loadings of film F=4.9X 10-I0mol-cm-2) at faster potential scan rates, peak currents proportional to (scan rate)12 explained charge transport is controlled by diffusion in the films .Protonated films have anionic exchange properties. The poly-Hemin electrode shows good electrocatalytic reduction for oxygen. The experimental results showed that the peak potential of electrocatalytic reduction for oxygen was influenced by solution pH. The number of electron transfer in the reduction process is near 4 based on the Ipocu1/2 linear relation. After a long period reduction of oxygen, the electroactivity of film was abolished.In 0.lmol-L-1 KC1 solutions reduction and oxidation peak of Vitamin B1 were obtained by cyclic voltammetry. The oxidation and reduction peak potentials were at 0.125V and -0.050V. Cyclic voltammograms of Vitamin Bl in PBS (pH=5) did not exhibit redox waves. The polymer film of VitaminB1 was obtained at a graphite carbon electrode by cyclic voltammetric method in PBS. Cyclic voltammograms of the film electrode in PBS(pH=5) exhibited one pair stable and reversible redox waves , Ep.a=0.350V, Epc=0.325V. So the polymer film of VitaminBi differs from monomer VitaminB]. For poly-VBi films peak currents proportional to (scan rate )l/2 ,the experimental results showed that the charge transfer process in the modifier film wasABSTRACTcontrolled by the diffusion. The reduction and oxidation peak potentials of Poly-VBi were influenced by solutions pH. The Poly-VBi modified electrode showed a good catalytic ability to epinephrine and dopamine. According to the results of cyclic voltammetry, the eletrocatalytic reactions of dopamine and epinephrine at poly-VBi electrode are similar to ECE process. In addition, the eletrocatalytic oxidation peak currents had linear relationship with concentrations of epinephrine and dopamine.The preparation of poly-Riboflavin (RF) chemically modified glassy carbon electrode by cyclic voltammertric measurements. Cyclic voltammograms of the film electrode in PBS (pH=6.6) exhibited one pair redox waves, Ep.a=-0.425V, Ep,C=-0.5V. For poly-RF films peak currents proportional to (scan rate )1/2 . From voltammertric data the surface coverage is calculated to be 7.7X 10"9mol-cm"2.The Poly- RF modified electrode showed a good catalytic ability to cysteine whatever in alkaline PBS or acidic PBS. The oxidation peak of cysteine occurred at potential 0.55V on the Poly- RF modified electrode in alkaline PBS and was not shift in different pH solution. The mechanism of the catalytic electroxidation of cysteine on riboflavin modefied glassy carbon electrode are discussed. The method for the determinations especially the quantitative analysis are also worked on. Furthermore, the eletrocatalysis of asorbic acid and oxygen were studied on the Poly- RF modified electrode in this work .The oxygen was reduction at potential -0.3V on the Poly- RF modified electrode. And the potentials of cysteine and oxygen on the Poly- RF modified electrode in alkaline PBS did not change in different pH solutions.Electropolymerization of brilliant cresyl blue and safranin T produce stable and electrochemically active films in aqueous solutions on graphite carbon electrode. Cyclic voltammetry were used to study the growth of poly...