Studies On The Preparation And Analytical Application Of Carbon Nanotubes Composite Materials Modified Electrode

At present, the application of nano-materials, especially carbon nanotubes and its composites as new chemically modified materials is a new direction in the field of chemically modified electrodes. It is important to establish new analytical methods with high-sensitivity and selectivity.In this paper, a variety of new carbon nanotubes composites modified electrodes were proposed. The properties of the carbon nanotubes composites modified electrodes were characterizd by several methods. Several methods for analyzing substances in environmental sciences and life sciences have been developed. The main works of this thesis are summarized as follows:1. A novel modified electrode was fabricated by electropolymerization of acid chrome blue K at a glassy carbon electrode modified with multi-walled carbon nanotubes and used for simultaneous voltammetric determination of dihydroxybenzene isomers. The Poly-ACBK/MWNTs/GC electrode was characterized with scanning electron microscopy (SEM) and cyclic voltammetry(CV). The electrochemical performance of dihydroxybenzene at the Poly-ACBK/MWNTs/GC electrode has been investigated by cyclic voltammetry. It was found that Poly-ACBK/MWNTs/GC electrode has excellent electrocatalyse and selectivity toward oxidation of dihydroxybenzene. A linear relationship between anodal peak current and concentration of hydroquinone, catechol and resorcinol was obtained in the range of 1×10-6^-1×10^-4 mol·L^-1.2. A novel modified electrode was fabricated by electropolymerization of bromophenol blue at a glassy carbon electrode modified with multi-walled carbon nanotubes and used for simultaneous voltammetric determination of dihydroxybenzene isomers. The Poly-BPB/MWNTs/GC electrode was characterized with SEM and CV. The electrochemical performance of dihydroxybenzene at the Poly-BPB/MWNTs/GC electrode has been investigated by CV. It was found that Poly-BPB/MWNTs/GC electrode has excellent electrocatalyse and selectivity toward oxidation of dihydroxybenzene. A linear relationship between anodal peak current and concentration of hydroquinone, catechol and resorcinol was obtained in the range of 1×10-6^-1×10^-4 mol·L^-1.3. A novel nano-silver coated multi-walled carbon nanotubes composites modified electrode was prepared. The application of the modified electrode for determination of trace thiocyanate is demonstrated for the first time. The property of nano-silver coated multi-walled carbon nanotubes composites was characterized with SEM, X-ray powder diffraction (XRD) and CV. The electrochemical behaviour of thiocyanate at the nano-Ag/MWNTs/GC electrode was investigated by CV. It was found that there was a linear relationship at the range 2.5×10?9 to 5×10?8 mol·L-1 and 5×10?8 to 1×10?6 mol·L-1 of thiocyanate with the decrement of anodal DPV peak currents. The limit of detection was 1×10?9 mol·L-1(S/N=3)and is better than the other thiocyanate-determination methods. Actual urine and saliva samples of smoker and non-smoker were analyzed and satisfactory results were obtained.4. A novel modified electrode was fabricated by electro-absorbption of hemoglobin (Hb) at Ag/CNT/GC electrode. The electrochemical properties of the modified electrode were investigated by CV. It was found that the modified electrode has obvious electrocatalysis toward the reduction of oxygen. There was a linear relationship between the currents of reduced peak with the volume of pumped air. An ectrochemical method for the determination of oxygen in water has developed.5. The nano-Ag/MWNTs/GC electrode has been fabricated with nano-silver coated multi-walled carbon nanotubes composites. The modified electrode was characterized with SEM and CV. It was found that the modified electrode has electrocatalysis toward the reduction of hydrogen peroxide. The modified electrode could be used to direct determination of hydrogen peroxide. There were linear relationships in the range 3.5×10-4⁵.5×10-3 mol·L-1 and 5.5×10-3 1.5×10-2 mol·L-1of hydrogen peroxide, respectively, with the of cathodic differential pulse voltammetric peak currents. The limit of detection was 2×10-4 mol·L-1. Actual samples were analyzed and satisfactory results were obtained.6. A nano-Ag/MWNTs/GC electrode has been fabricated with nano-silver coated multi-walled carbon nanotubes composites. The electrochemical properties of chloride ion at the modified electrode were investigated by CV. It is found that the differential pulse voltammetry (DPV) currents of anode peak decreased with the addition of high concentration chloride ion. There was a linear relationship at the range 8×10?3-0.1 mol·L-1 with the decrement of anodic DPV peak currents. The application of the modified electrode for determination of high concentration chloride ion has developed. Actual tap water samples were analyzed by this method.7. A new poly-methylene blue/single-wall carbon nanotubes modified glassy carbon electrode was proposed and applied to detect NADH successfully. The synergistic electrocatalytic effect of the modified electrode toward oxidation of NADH has been investigated. It was found that there was a linear relationship at the range 5.0×10-6- 7.0×10-4 mol·L-1with the anodal peak currents and the concentration of NADH.