| Twocompositefilms[PEI/PMo9V3-Pd@PtNPs/PEI/CNTs]6and[PEI/PB/PEI/PW9V3-Pt@Pd NPs]6 were fabricated by electrostatic layer-by-layer self-assembly method with vanadium-substituted polyoxometalate.Firstly,scanning electron microscope?SEM?and atomic force microscope?AFM?were applied to characterize the surface morphology of the composite films,and transmission electron microscope?TEM?was used to examined the diameter of nanoparticles.The growth process of the composite films was monitored by UV-vis spectroscopy.X-ray photoelectron spectroscopy?XPS?was applied to present a systematic characterization for the composite film.Secondly,in the phosphoricacid buffer solution,cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?were used to investigate the electrochemical catalytical activities of two composite films.At last,the sensing properties and real samples analysis were verified by current-time electrochemical technology.The results were shown as followed:Firstly,the composite film[PEI/PMo9V3-Pd@Pt NPs/PEI/CNTs]6 was investigated to have a good catalytic activity for the oxidation of DA by cyclic voltammetry?CV?,and optimized experimental conditions like the best pH and number of layers were studied,too.Electrochemical impedance spectroscopy?EIS?proved that the composite film owned the higher electron transfer rate and smaller resistance.Next,current-time response electrochemical technology was used to exam the sensing ability.The result presented that in 0.2 M phosphate buffer solution?pH=7.30?,the composite film sensor[PEI/PMo9V3-Pd@Pt NPs/PEI/CNTs]6 had a linear range of DA to be 2.5×10-8 M1.78×10-4 M,and a limit of detection to be1.25×10-8 M?S/N=3?.Meanwhile,the composite film sensor had an excellent anti-interference property to six kinds of potential interfering species like ascorbic acid?AA?,uric acid?UA?,glucose,L-cysteine,L-tryptophan and L-glutamic acid.Finally,the standard addition method was used to exam the real sample recoveries of the composite film sensor in bovine serum and dopamine hydrochloride injection,the recoveries were in the allowable error range.That is to say,the composite film sensor[PEI/PMo9V3-Pd@Pt NPs/PEI/CNTs]6 can be a potential DA sensor in the application detection.The same electrochemical technology was used to investigate electrochemical properties and sensing abilities of the composite film[PEI/PB/PEI/PW9V3-Pt@Pd NPs]6.The result showed the incorporation of the three kinds of active components would improve the electrocatalytic activity to the reduction of H2O2 and electron transfer rate greatly.And in 0.2 M phosphate buffer solution?pH=7.0?,the composite film sensor[PEI/PB/PEI/PW9V3-Pt@Pd NPs]6 had a linear range of H2O2to be 4.0×10-7 M2.647×10-3 M,and a limit of detection to be 4.0×10-7 M?S/N=3?.In addition,the composite film sensor had an excellent anti-interference property to six kinds of potential co-exist interfering species like KIO3,Glucose,ZnSO4,CaCl2,MgSO4 and NaCl.The sensor had a good stability as well.Besides,the sensor was applied in the detecting H2O2 in five kinds of real samples,including tap water,pure water,mineral water,milk and apple juice,the recoveries were all in the allowable error range.The result of the experiment demonstrate that the composite film sensor[PEI/PB/PEI/PW9V3-Pt@Pd NPs]6 would be a potential candidate sensor for practical detecting H2O2 in the drinks. |
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