Fabrication And Sensing Properties Of Composite Film Based On Vanadium-substituted Tungstophosphate

With the development of materials science, the fabrication ofmultifunctional composite films with optical, electrical and magnetic propertiesbecomes more and more important in contemporary materials science. Twocomposite films based on vanadium-substituted tungstophosphate{PEI/[P₂W₁₇V/PEI-CdS]n/P₂W₁₇V} and {PEI/PSS/[PDDA/P₂W₁₇V-CNTs]10}were fabricated by electrostatic layer-by-layer self-assembly method. These twocomposite films were characterized by UV-vis spectroscopy, cyclic voltammetry（CV）, atomic force microscopy （AFM）, scanning electron microscopy （SEM） andX-ray photoelectron spectra （XPS）. The property of electrochemical sensing ofthe composite film was carried on electrochemical workstation and the resultswere shown as followed:In0.05M phosphate buffer solution （pH=7）, the composite film{PEI/PSS/[PDDA/P₂W₁₇V-CNTs]10} can be performed for nitrite with goodcatalytic at+0.9V by cyclic voltammetry and chronoamperometry. The resultsshow that the nitrite sensor with10bilayers has a broad linear range of5×10^-8to2.13×10^-3M, a low detection limit of0.0367μM （S/N=3）, a high sensitivityof0.35mA·mM^-1, an excellent anti-interference property in the presence of otherpotential interfering species and a good stable. In addition, the as-prepared sensorwas successfully employed for determination of nitrite in real samples, whichindicated that the proposed sensor with P₂W₁₇V and CNTs would representpromising material for future applications in amperometric sensor.The electrochemical properties of the composite film {PEI/[P₂W₁₇V-CNTs/PEI-CuO]10/P₂W₁₇V-CNTs} demonstrate that the as-prepared compositefilm has good catalytic activity for determination IO3-. After adding iodate in the 0.5M （pH=2.5） Na₂SO₄-H₂SO₄buffer solution, the composite film showsobvious response current at about-0.5V. When0.5mM IO3-was added, thecatalytic efficiency of the as-prepared composite film was164.12%. A series ofexperiment results show that the iodate sensor with10bilayers has a broad linearrange of1.25×10^-7M to1.63×10^-4M, a low detection limit of0.015μM （S/N=3）, a high sensitivity of4.82mA·mM^-1. Moreover, almost no interference wasobserved in the presence of possible interference species, demonstrating that thisas-prepared sensor has very superior selectivity. And, the composite film has agood stability. The as-prepared sensor has been successfully used to detect iodatein real samples.