Fabrication And Sensing Properties Of Polyoxometalate/Nanomaterials Composite Films

Two composite films {PEI/P2W17V/CNTs-CS/AuCo/P2W17V} and{PEI/P8W48/CNTs-CS/Ni/P8W48} were fabricated by electrostatic layer-by-layerself-assembly method and electrochemical deposition. By transmission electronmicroscope (TEM), scanning electron microscope (SEM), and X-ray photoelectronspectroscopy (XPS) to presents a systematic characterization for the composite film.In the pH=7.0, two composite films is verified by electrochemical methodperformance. The results were shown as followed:The electrochemical behavior of the composite film{PEI/P2W17V/CNTs-CS/AuCo/P2W17V} was investigated by cyclic voltammetry(CV), electrochemical impedance spectroscopy (EIS), differential pulsevoltammograms (DPV) and current-time response, and presents an excellentanti-interference property in the interfering species, as well as the excellent stabilityand selectivity in the presence of common interfering substances. In0.2M phosphatebuffer solution (pH=7), the composite film displays high electrocatalytic activity at0.172V and0.288V for dopamine (DA) and uric acid (UA). The linear responserange of the composite films for simultaneous detection of DA and UA were1.25μMto282μM and0.75μM to167μM, the detection limits were0.15μM and0.25μM(S/N=3), correspondingly. The composite film has an excellent anti-interferenceproperty in the presence of other potential interfering species (such as: ascorbic acid,glucose, L-cysteine, L-tryptophan, L-glutamic acid and lactic acid) and a goodstable. The composite film has been successfully used to detect dopamine and uricacid in the bovine serum real samples.The electrochemical properties of the composite film{PEI/P8W48/CNTs-CS/Ni/P8W48} was investigated by cyclic voltammetry (CV),electrochemical impedance spectroscopy (EIS), differential pulse voltammograms(DPV) and current-time response, the results show that the composite film has good catalytic activity for determination nitrite. In the0.2M (pH=7.0) phosphate buffersolution, the composite film for nitrite shows an obvious response current at0.75V, abroad linear range of1.25μM to2500μM，a low detection limit of0.02μM (S/N=3). Moreover, The composite film has an excellent anti-interference property in thepresence of other potential interfering species (such as: glucose, acetic acid, citricacid, potassium bromate, potassium iodate, sodium carbonate, potassium chloride,and fructose), as well as the excellent stability and selectivity. The composite film assensor has been successfully used to detect nitrite in fruit juice real samples, theresults show that the composite film has potential applications in the field ofpreparation of nitrite sensor.