The Optical And Electrochemical Property Of Keggin Structure Molybdophosporic Acid In Chemistry Modified Electrode

Heteropoly acids has excellent redox stabilities and photocatalytic, electrocatalytic properties, owing to their structural and electronic versatility. The property makes them very useful in the electrochemical sensor material. In this paper we have improved the modified electrode behaviour utilizing the unique optical and electrochemical property of Keggin structure molybdophosporic acid, thus we have obtained two kinds of molybdophosporic acid modified electrodes with good sensitive response, high stability and outstanding electrocatalytic property.In the first part of this paper, gold nanoparticles supported with Keggin phosphododecamolybdates (PMo₁₂-NG) were prepared by simple photoreduction technique. In which, the heteropolyanions acted as reducing agents, photocatalysts and stabilizers. The reaction mechanism and reaction condition were also discussed. It has shown that, thanks to the charge-transfer effect between PMo₁₂ and DMF, PMo₁₂ can also be the photoreduction reagent to prepare the gold nanoparticles. Within the proper irradiated time by UV light and dosage of DMF, we can get the monodispersed and stable gold nanoparticles. Then, PMo₁₂-NG were successfully immobilized on the glassy carbon electrode surface with PVP layer-by-layer assembly mutillayer film and a PMo₁₂-NG modified electrode (PMo₁₂-NG/PVP/GC) was obtained. The morphology of resulting gold nanoparticles and redox behaviour of PMo₁₂-NG/PVP/GC CME were discussed. The results showed that the PMo₁₂-NG/PVP modified electrode exhibited high sensitivity, good reproducibility and excellent electrocatalytic activity toward the IO₃^-,BrO₃^-,NO₂^-,H₂O₂. The heterogeneous catalytic rate constant of PMo₁₂-NG/PVP/GC CME is 1.34×10⁵ mol^-1·L·s^-1 by chronoamperometric measurement.In the second part of this paper, the charge-transfer compound (TMB)3PMO12O40 (TMB-PMo₁₂)film modified GC electrodes have been prepared by sol-gel technique and its electrochemical properties was studied by cyclic voltammetry method. Experimental results show that in one hand this charge-transfer compound have good redox activity and electrocatalytic properties as the same of its precursors, in anotherhand, it has its own unique properties. The TMB-PMo₁₂ modified electrode exhibits excellent catalytic activity for the reduction of IO₃^-. Compared the heterogeneous catalytic rate constant of TMB-PMo₁₂ CME with PMo₁₂ CME, 3.04×10⁴ mol^-1·L^-1·s^-1, we can see that the reproducibility of PMo₁₂-NG/PVP/GC CME was far beyond the PMo₁₂/PVP/GC CME. By investigating the effect of the irradiation on the electrocatalytic reduction of IO₃^-, we can find that the photo-induced intramolecular charge transfer in the TMB-PMo₁₂ molecules has contribution to the overall electrocatalytic reduction of IO₃^- on the TMB-PMo₁₂ modified electrode.