Study Of Polyoxometalates On Anodic Aluminum Oxide/glass Carbon Electrode Electrochemical Properties And Application

Polyoxometalates (POMs) have been attracting much attention in electrochemistry field owing to their chemical structure and electronic versatility. Recently, POMs can be modified on the electrode surface by the following methods: (1) electrochemical deposition, (2) adsorption on an electrode surface, (3) polymers mixing, (4) doping in conducting polymers, (5) the sol-gel method and other strategies. The capability of the compound is excellent acid and alkali, redox activity or dual function catalyzer in the system of homogeneous or unhomogeneous. The catalyze of POMs commonly includes acid catalyze and redox catalyze. Its activity and selectivity is improved obviously by changing chemical surroundings of POMs compound. Thereby the application of POMs compound is enlarged by exploiting new catalyzed reaction.Porous anodic aluminum oxide (AAO) has many characters. For example: resisting high-tempering; porous distributed uniformly and orderly, and its controllable size. AAO as templates can synthesize nanowire or nanometer-sized tube, and can become biosensor and reactor. Therefore it is extensively used anodic oxide material. Using chemical and physical character of AAO can prepare and develop various functional materials, which apply to various fields.First, we have prepared high sensitivity POMs nanoparticles modified electrode by an anodic aluminum oxide (AAO) membrane covering glass carbon electrode surface and containing polypyrrole and PMo12O403- (PMo12- PPy) by electrochemical cycling scan. The porosity AAO films were prepared by anodization process. The porosity of the AAO films ranges from 40% to 55% being assessed by cycle voltammetry and SPM. The surface topographies of 12-molybdophosphoric nanoparticles of adulterating PPY on AGCE and GCE have been investigated using Atomic Force Microscope (AFM). Electrochemistry technique was performed in order to evaluate the cyclic voltammetry characteristics of 12-molybdophosphoric nanoparticles. Meanwhile, we have been examined the factors of affecting on the electrochemistry character, and preliminarily studied the electrocatalytic activity of 12-molybdophosphoric nanoparticles modified electrode. Second, this paper first applied 12-molybdophosphoric nanoparticles modified electrode to determine environment sample. This modified electrode possesses not only simple preparation process, but also the long-term stability. To compare with PMo12-PPy/GCE, the remarkable advantages of the modified electrode (PMo12-PPy/AGCE) have high sensitivity and favorable electrocatalytic behavior, and the CV reversibility was improved obviously. In the study, we adopted current-time curve method to determine nitrous acid. The linear range is 8.0×10-7～0.01 mol/L, the detection limit of NO2- is 1.0×10-9 mol/L. The experiment result shows that the method can be the exact, sensitive, quick and handy for determining nitrous acid in environment water sample. The high sensitivity nanoparticles modified electrode has prospectively important worth to study and apply in biology and chemical sensor, and provides a new method for PMo12 system in electrocatalytic study and applications. Third, the AC impedance is an important paramter to describe the electrode interface property. Through determining electrochemical impedance, we may know physical and chemical properties of interface system between the electrode and electrolyte solution, and electrode reaction mechanism and dynamical parameter at a potential. The paper has investigated 12-molybdophosphoric nanoparticles of adulterating PPy on AGCE by the electrochemical impedance spectroscopy. The charge transport ability of PMo-PPy/AGCE is better and rapider redox rate than PMo-PPY/GCE through analyzing the impedance data. Fourth, the paper studied AAO film effect on electrochemical property of equable SiW12(H4SiW12O40·nH2O)solution, and compared AAO/ GCE with GCE of electrochemical action in SiW12 solution. The reversibility of SiW12 with AAO/GCE in 0.5 mol/L H2SO4 solution was impr...