The Research Of Nanomaterial Modified Electrodes And Their Application In The Environmental Analysis

The small size effect, the surface and interface effect, the quantum size effect and the macroscopic quantum tunnel effect of nanometer materials results in series of interesting physical and chemical properties, which have become hotspots in scientific and technological fields in recent year. The nano-materials have been applied in many fields including nanoelectronics, nanochemistry, sensors, environmental monitoring, medicine, biotechnology and so on. Molecular imprinting is a method for making selective binding sites in synthetic polymers by using a molecular template. After the removal of the template, the remaining polymer gives rise to"memory sites"that are sterically and chemically complementary to the imprint species. Compared to the natural entities such as antibodies and enzymes, the artificially generated molecular recognition materials possess the virtue of anti-harsh environment, high stability and long use life which made them is useful for analytical separations, in particular in solid-phase extraction, membrane separation technique, separation of isomers and sensors.At present, the application of nano-materials as new chemically modified materials is a new trend in the field of chemically modified electrodes. In this paper, precious metals nanoparticles, carbon nanotubes were applied to composite electrochemical sensors. Nanoparticles/nanotubes composite possess interesting synergistic properties which can enhance the catalysis activity of the modified electrodes. With the high affinity of the–NH2 groups towards gold surface, gold nanoparticles can be self-assembled on the electrode and acted as excellent catalyst. Due to the high selectivity of molecular imprinting technolygy, the self-assembled imprinting film modified electrodes were constructed. In detail, the thesis including such study as follows:1. Platinum particles were electrochemically deposited on glassy carbon electrodes (GCE) modified with carbon nanotubes. The chemically modified glassy carbon electrodes with platinum particles and carbon nunotubes (Pt/CNTs/GCE) were used as formaldehyde sensors. Electrochemica1 behaviors of formaldehyde at Pt/CNTs/GCE were investigated by cyclic voltammetry (CV) and linear scan voltammetry (LSV). Experimental conditions were optimized, and a voltammetric method for determining formaldehyde was developed.2. Gold nanoparticles were electrochemically deposited on glassy carbon electrodes modified with carbon nanotubes (Au/CNTs/GCE). Electrochemica1 behaviours of methyl-parathion at Au/CNTs/GCE were investigated by cyclic voltammetry and linear scan voltammetry. Field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD) techniques were used for characterization of the composite. The effect of pH, accumulation time and amount of the deposited gold microparticles on the reduction peak current of methyl-parathion at the Au/MWCNTs/GCE were investigated.3. The modified sensors were fabricated by N-[3-(trimethoxysilyl) propyl]-ethylene diamine (TSPED) or (3-aminopropyl)-trimethoxysilane on glass carbon electrodes. Colloidal gold particles were modified by self-assembling onto the amine groups of the sol-gel. Electrochemica1 behaviours of nitrite on sol-gol and gold nanoparticles modified glassy carbon electeodes (AuNPs/TSPED/GCE) and AuNPs/ATS/GCE were investigated by differential pulse voltammetry (DPV) and differential pulse amperometry (DPA).4. Cyclic voltammetry was employed in the process of electropolymerization on gold electrode. Parathion was used as template molecule; tetrabutyl ammonium perchlorate was used as supporting electrolyte and o-aminothiophenol as polymer monomer. Parathion imprinted and nonimprinted polymer films were exposed to a series of closely related compounds and the sensor exhibited good selectivity and sensitivity to parathion.5. A polypyrrole (PPY) doped by phosphotungstic heteropolyacid (PW12) and Nafion (Nf) doubly layer modified glassy carbon electrode (Nf/PW12/PPY/GCE) was prepared. The Nafion layer modified on the surface of electrocatalyst could effectively eliminate the interferences from common species anion in biological samples such as ascorbate, urate and nitrite. The electrochemical behaviours of nitric oxide at the Nf/PW12/PPY/GCE were investigated by cyclic voltammetry.