Study On The Preparation And Application Of Transition Metal Compounds Modified Electrodes

The advent of the theory of Chemical Modified Electrode (CME) had broken through the traditional concept of electrode/electrolyte interface and initiated a new research field of controllable electrode interface. The CME can be endowed the designed function by assembling or clipping the variety of function groups of organic, inorganic compounds, complexes and polymers, still the special morphology of porous, micro and nanometer materials. By using the unique modifier, the selectivity and sensitivity can be improved and the intended function can be realized. The materials chemistry, inorganic chemical and electrochemistry are exploited for an innovative and hopeful research field by the application of new materials in CME.This paper focused on the preparation of CMEs by novel transition metal complexes and nano metal oxides. The content was summarized as follows:Chapter one was a review in literature. The basic concept of sensor and CME, especially the application of transition metal complexes and nano metal oxides in the CMEs was reviewed.From Chapter Two to Chapter Four, the contents were focused on the preparation and application of novel CMEs using transition metal complexes. The detail of the investigation was as follows:1. Novel complex [CuBAim](ClO4)2 was modified on the surface of a pyrolytic graphite electrode by adsorption method. The redox properties of the modified electrode were investigated by cyclic voltammogram in different pH solutions. Also the oxygen catalytic mechanism on the modified electrode was deduced.2.4,4'-Bipyridine bridged dicopper complex was firstly grafted on the surface of a glassy carbon electrode using electrodeposition method. The morphology of the modified electrode surface was studied by scanning electron microscopy (SEM). The electrochemical behavior of the modified electrode was investigated by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). The application of the modified electrode in the separating and determining of ascorbic acid, uric acid, dopamine or other small molecules such as L-cysteine and hydroquinone was studied in detail. A sensitive and selective voltammetry technique for determination of ascorbic acid and uric acid, ascorbic acid and dopamine in mixture solutions simultaneously were established.3. A tetranuclear cluster crystal (TCuPMS) was synthesized based on the reaction of cupric perchlorate and 4-(3-pyridyl)-2-mercapto imidazole in methanol medium at room temperature. The TCuPMS or TCuPMS/CNT composite materials were grafted on the surface of glassy carbon electrodes using electropolymerized method. The morphology of the modified electrode surfaces were studied by SEM. The electrochemical behaviors of the modified electrodes were investigated by CV and EIS. The fabrication conditions of the modified electrodes were examined. The basic parameters of the modified electrodes were calculated by electrode kinetics theory. The results indicated that the sensitivity and selectivity were enhanced by the synergistic function of TCuPMS and CNT. It was found that the fabricated modified electrodes exhibited high electrocatalytic activity for hydrogen peroxide and oxygen reduction. The electron transfer numbers and catalytic reaction rate constants were calculated. Based on these kinetic parameters, the oxygen and hydrogen peroxide electrocatalytic mechanism at the modified electrode were deduced.From Chapter Five to Chapter Six, the contents were focused on the synthesise and application of novel CMEs modified by nano metal oxides. The detail of the investigation was as follows:1. Flowerlike Co3O4 nanoparticles were synthesized by hydrothermal technique. A sensitive nano Co3O4 modified biosensor was fabricated by simple drop coating method. The morphology of the modified electrode surfaces were studied by SEM and X-ray diffraction (XRD) technique. The electrochemical behavior of the modified electrode was investigated by CV and EIS. The fabrication conditions of the modified electrode were examined. The parameters of electrode surface and the amount of saturated adsorption were calculated by electrode kinetics theory. The application of the modified electrode in the determining of rutin, uric acid and quercetin was explored in detail;the determination limits were 5.0×10-7 mol/L, 5.0×10-7 mol/L and 1.0×10-7 mol/L, respectively.2. Fe3O4 nanoparticles were synthesized by coprecipitation technique. By a simple dropcoating method, Fe3O4 nanoparticles were modified on a glassy carbon electrode to fabricate an amperometric sensor for cefotaxime sodium (CS) detection. The micro structure and electrochemical behavior of the sensor were investigated by scanning electron microscope and electrochemical impedance spectroscopy (EIS). The electrocatalytic ability of the sensor to CS reduction reaction in Britton-Robinson buffer solution was investigated by cyclic voltammogram and differential pulse voltammogram. Results suggested that the proposed sensor exhibited an excellent electrocatalytic activity toward the reduction of CS with a well-defined reduction peak at -0.90 V. The catalytic currents of CS were linearly dependent on the concentrations of CS in the ranges from 0.07 to 1?mol/L and from 1 to 45?mol/L, with the detection limit of 5.0×10-8 mol/L. The sensor exhibited good stability and reproducibility, and it was successfully applied to determine the CS concentrations in CS injection samples.