Characterization And Properties Of The Modified Polyaniline Electrode By Transition Metal Ions

The chemically-modified electrodes(CME) have been a most burgueoning and of the most flourish research realms in the electrochemistry and electroanalytic chemistry. It was for the moment widely appied in many case such as life sicence, envioronment sicence, energy source sicence, analytic sicence, electronics and meterial sicence. The polyaniline modified electrode has multihole, homogeneous, good electrical conductivity, environmental stability and other advantages. However, the conductivity performance and catalytic performance of polyaniline modified electrodes is poor. In order to optimize the performance of polyaniline modified electrode, in ous papers we study the effect of transition metal ions (M²⁺=Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Zn²⁺) on the electrochemical synthesis of polyaniline was carried out under cyclovoltammetric conditions with the corresponding metal chloride in hydrochloric acid electrolyte. The products were characterized by FT-IR spectroscopy, SEM and EIS. we also reseach the reason of the current plus of the polyaniline doped by copper ion, and electrochemically synthesised polyaniline/Pt (PANI) can be used to measure copper ion concertraions. The main contents are as follows:(1)Polyaniline containing transition metal ions(M²⁺=Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Zn²⁺) were synthesized by cyclic voltammetric with the corresponding metal chloride in solution. The products were characterized by FT-IR spectroscopy, SEM and EIS. Experimental results shows that the film of Pani-Cu²⁺ is obviously different to Pani-M²⁺(M²⁺= Ni²⁺, Mn²⁺, Co²⁺, Zn²⁺) in both the shape of oxidation-reduction peaks and the first anodic peak current. Moreover, a particular phenomenon, i.e., a current plus was observed on the I-E curve of Pani-Cu2+ for the first oxidation peak.(2)To discover the reason of the current plus of Pani-Cu²⁺, the experiment was carried for three groups in different electrolytical solutions by cyclic voltammogram. The experimental results shows that the co-activation of copper ion and chloride ion in acid solution accelerates the polymerization rate of aniline, which lead to that the first anodic peak current of Pani-Cu²⁺ increases sharply. According to the coordination theory, the different polymerization rate is caused by the different structure of transition metal ions at the same electrolytical concentration. Transition metal ions are able to coordinate to imine nitrogen atoms of the polymer backbone. The structures of compositions MCl₄^2- made up of corner-sharing MCl₆ octahedra or planes of isolated MCl4 tetrahedra in HCl solutions.(3)A new chemically modified Pt electrode under cyclovoltammetric conditions has been prepared by using polyaniline as a modifier, the electrochemical behavious of copper(â…¡) ion on the modified electrode have been studied. The polyaniline electrode was studied by X-ray diffraction, Scanning Electron Microscope and TG analysis. A new approach is developed for sensitive and accurate determintion of copper ion by the polyaniline electrode, the peak of copper ion on polyaniline/Pt is proportional to concentration of copper ion between 1×10^-61×10^-3mol/L,the detection limit is 2.1369×10^-6mol/L.