Preparation And Electrochemical Properties Of The Electrodes Modified Acid-based Chemical

Most of the polyoxometalates (POMs) are stable in solution and can occur a series of continuous reversible oxidation-reduction processes. The redox potential of the POMs can be adjusted by changing the heteroatom or coordination atoms without the influence of the basic framework of the POMs, so the POMs can be used as a kind of good oxidation-reduction catalyst. The electrochemical properties of POMs attract more and more attention due to their versatile architectures and the superior electrochemical properties. Some POMs, especially sulfur as heteroatom, are unstable in aqueous solution, which can be stablized by the formation of organic-inorganic hybrids,In this paper, two layer-by-layer (LBL) films{PEI/[PMo10V2]}n (1) and PAA{PEI[PMo9V3]}n (2), constructed by the vanadium substituted Keggin POMs, H5PMo10V2O40and H6PMo9V3O40, and polyelectrolyte (PEI polyethylenimine, PAA polyacrylic acid) coated to the ITO, have been successfully fabricated by LBL self-assembly molecular method. LBL deposition is confirmed via UV-vis absorption and cyclic voltammetry measurements. SEM showed that the film surfaces are homogeneous and smooth. In0.5M H2SO4aqueous solution, the electrochemical and electrocatalysis behaviors of the films,{PEI/[PMo10V2]}n and PAA{PEI/[PMo9V3]}n, have been investigated. All of the two films show four pairs of redox peaks, and the redox peak potentials have a little change with the number of the substituted vanadium, and the peak currents increase with the increase of the layer number. Both of the film electrodes show good electrocatalysis on the reduction of NO2-, BrO3-and ClO3".The two organic-inorganic heteropoly compounds,(C16H18N3S)2[S2Mo1VMo17VlO62] CH3CN (3) and [(CH3)2NH2]6SMo4VMo8Vl040(4) based on the Keggin and Dawson type molybdosulfates have been also synthesized, and furthermore, they were fabricated into carbon paste electrodes (3-CPE and4-CPE). The electrochemical and electrocatalysis behaviors of3-CPE and4-CPE in1M H2SO4aqueous solution have been investigated.3-CPE and4-CPE exhibit good stability and surface renewal, and good electrocatalysis on the reduction of NO2-, BrO3-, ClO3-and H2O2. Redox peak potentials of the two CPEs are pH-dependent, and with the increase of pH, the redox peak potentials of the CPEs move to the negative direction.In this paper, three organic-inorganic compounds based on the Keggin type polyoxometallates (PMo12O403-. SiMo12O404-and GeMo12O404-) and new methylene blue (NMB) have been also synthesized:(5)(6)(7)X ray single crystal data analysis showed that all of the three compounds belong to triclinic crystal system, there exist strong CH… and NH…O hydrogen bonding between the POM anions and NMB cations, while NMB molecules form tetramers through π-π stacking. The one dimensional organic chains constructed by the tetramers and the one-dimensional inorganic chains formed by the POM anions arranged alternately to form3D supramolecular compounds. The UV-vis spectra and fluorescence spectra of the three heteropoly compounds show absorption peaks attributed to POMs and NMB, but the position of the absorption peaks have a little shift, which indicate the interactions between POM and NMB.