Abstract:

 A composite film modified glassy carbon electrode containing heteropolyanion was fabricated by attaching a Keggin—type heteropolyanion, H3(PMo₁₂O₄₀)·H₂O, to a 3-aminopropyltrimethoxysilane (APMS) layer, which was self-assembled on an electrochemically activated glassy carbon electrode through the formation of C—O—Si bond. XPS and cyclic voltammetry were used for the characterization of the composite film. The results showed  that PMo₁₂O₄₀^3- was linked with APMS through the coulombic interaction between PMo₁₂O₄₀^3-and amine groups of APMS (PMo₁₂O₄₀^3--APMS), which greatly improved the film stability. The PMo₁₂O₄₀^3--APMS modified electrode showed three reversible redox pairs of PMo₁₂O₄₀^3- with a smaller peak-to-peak separation, which  was stable in a larger pH range compared with that in the solution phase. The catalytic properties of the modified electrode for those reduction of ClO₃^- 、BrO₃^- and  IO₃^- were studied. The modified electrode exhibited better electrocatalytic activities for those three anions compared with the PMo₁₂O₄₀^3- modified glassy carbon electrode. The detection limits were  1.5×10^-5, 1.0×10^-6, 5×10^-7mol／L for ClO₃^-, BrO₃^-and IO₃^-  seperately.

Key words: phosphomolybdic acid, 3-aminopropyltrimethoxysilane, self-assembled film, modified electrode