Preparation And Analytical Application Of Some Nanocomposite Material Modified Electrodes

In recent years,nanomaterials have been widely used in electrochemical sensor owing to their large specific surface area,excellent biocompatibility,small size effect,strong electro-catalytic activity,great adsorption capacity and good stability.In particular,graphene,carbon nanotubes,nanometallics and nanocore-shell structures have attracted much attention from researchers in the fields of biological and environmental pollution detection.Electrochemical sensors have become one of the most widely used analytical tools due to their many advantages,such as low cost,simple operation,fast response,high sensitivity and good selectivity.So,in this theis,by using graphene-carbon nanotube composites,gold nanoparticles/carbon nanotubes-porphyrin composites,gold nanoparticles-carbon nanotubes/graphene composites,gold@silver-carbon nanotube/ graphene composite materials such as modified materials,a series of excellent electrochemical sensors have been successfully fabricated.The morphologies,structures and electrochemical propertie of the modified materials and resulted electrodes,such as scanning electron microscopy(SEM),transmission electron microscope(TEM),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS)and some related electrochemical techniques such as cyclic voltammetry(CV),differential pulse voltammetry(DPV),chronocoulometry(CC),and electrochemical impedance spectroscopy(EIS),were characterized and obtained.This thesis mainly consists four parts as follows:1.A novel electrochemical sensor Gr-MWCNTs/GCE was developed by a simple drop-casting method with reduced graphene oxide-multiwalled carbon nanotubes composites prepare covalent linking as modified materials.Electrochemical behavors of ascorbic acid(AA),dopamine(DA)anduric acid(UA)on the modified electrode were studied by applying DPV,CV,CC and EIS technologies.The results showed that Gr-MWCNTs/GCE possessed good electrocatalytic activities toword the oxidation reactions of AA,DA and UA on the electrode and could separate the oxidation their peaks very well.Under the optimized experimental conditions,the peak currents varied linearly with the increasing concentrations of AA,DA and UA in the range of 300.0 to 690.0 ?mol·L-1,1.0 to 240.0 ?mol·L-1 and 14.0 to 100.0 ?mol·L-1,respectively,and the detection limits were 45.6 ?mol·L-1,0.47 ?mol·L-1 and 1.06 ?mol·L-1(S/N = 3),respectively.The modified electrode also displayed good selectivity,excellent reproducibility and high stability,which promised a practical application for rapid determination of DA,AA and UA in the real sample.2.By using Au NPs and as-prepared tetrakis(4-aminophenyl)porphyrin(TAPP)functionalized MWCNTs as modified materials,a novel electrochemical platform Au NPs/MWCNTs-TAPP/GCE was designed and prepared for simultaneous determination of p-acetaminophen(AMP)and p-aminophenol(AP)with drop-casting and electrodeposition procedures.The structures,morphologies and electrochemical performances were characterized in detal.The incisive oxidation current responses of AMP and AP at the modified electrode promised a sensitive and selective simultaneous determination of AMP and AP.Under optimized conditions,the peak currents were directly proportional to the concentrations of AMP and AP over the ranges of 4.5 to 500.0 ?mol·L-1 and 0.08 to 60.0 ?mol·L-1,respectively,and the limits of detection were 0.44 ?mol·L-1 and 0.025 ?mol·L-1(S/N = 3),respectively.In addition,the proposed modified electrode also showed excellent selectivity,reproducibility and long-term stability and has been applied successfully in simultaneous determination of p-acetaminophen and p-aminophenol in real samples with a satisfactory result.3.The graphene/gold nanoparticle-carbon nanotube composite film modified electrode(Gr/Au NPs-MWCNTs/GCE)was successfully prepared by drop-casting the mixed solution of graphene and gold nanoparticle functionalized mutilwalled carbon nanotube on the surface of glassy carbon electrode.The electrochemical behaviors of hydroquinone(HQ)and catechol(CC)on the modified electrode were studied by CV and DPV methods.The results showed that the modified electrode has outstanding electrocatalytic activities and separation effects for the electrochemical oxidation of HQ and CC.Under the optimum experimental conditions,favorable linear relationships were obtained between the oxidation peak current and the concentration of HQ and CC in the range of 8.0 to 45.0 ?mol·L-1 and 4.0 to 52.0 ?mol·L-1,and the detection limit were 0.96 ?mol·L-1 and 0.63 ?mol·L-1(S/N = 3),respectively.The method has been applied successfully for detection of HQ and CC in environmental sewage.4.By introducing Au@Ag core-shell nanoparticles functionalized mutil-walled carbon nanotubes onto the surface of electroreduced graphene oxide modified glassy carbon electrode(REGO/GCE),a novel Au@Ag NPs-carbon nanotube/graphene composite film modified electrode(Au@Ag-MWCNTs/REGO/GCE)was successfully prepared and the electrochemical behavior of 4-nonylphenol(4-NP)on the modified electrode was studied in detail by CV and DPV.The experimental results showed that Au@Ag-MWCNTs/REGO/GCE has excellent electrocatalytic property for 4-NP oxidation reaction.Under the optimum experimental conditions,the peak current of 4-NP showed a good linear relationship with the concentration in the range of 2.0 to 110.0 ?mol·L-1 with a detection limit of 0.24 ?mol·L-1(S/N = 3).The modified electrode has good selectivity and stability and can be used for the detection of 4-NP in environmental sewage.