Self-assembled Ultrathin Films Based On Graphite Oxide, Preparation And Electrochemical Properties Of Ppy Composite Film

Graphite oxide(GO), decorated with oxygen-containing functional groups(hydroxyl, carboxyl, carbonyl, epoxy groups et al.) on the basal as well as on the edge planes, possesses typical two-dimensional layered structure. The oxygen-containing groups endow graphite with improved chemical activities and enrich the intercalation properties of GO. The GO can combine with small polar molecules, metal atoms, oxides, even polymers to form kinds of composites by intercalation, which has been among the important topics of inorganic layer materials recently.Herein, multi-layered GO/polyelectrolyte composite ultrathin films absorbed on different substrates (glass, quartz, ITO conductive glass) were prepared via electrostatic layer-by-layer assembly technology. The influence of immersing time and solution concentration on film thickness and flatness was investigated. In addition, the adhesion of the films to substrates and the electrochemical behavior of the films were studied. It was found that, the composite ultrathin films with smooth surface and uniform thickness would be obtained by immersing alternately the substrates into polyelectrolyte and GO colloid solutions with a definite concentration for a short time. The GO would be completely exfoliated in more diluted GO colloid slution, which is convenient for the film assembly process. The ultrathin films adhered well onto the substrate and GO thin films spreaded aclinicly or curlily on the surface. Compared with the bare electrode, the electrodes modified with ultrathin films have higher capacity of electron transfer and have no obvious redox peak, indicating that they are electrochemical negative. The reductive ultrathin film has a small impedance value.Then polypyrole (PPy) films were electroploymerized using ITO conductive glass modified with ultrathin films as working electrodes and using seven different dopant aqueous solutions as electrolytes. The applied potential for electropolymerization was determined by linear sweep voltammetry (LSV), and appropriate polymerizing time was selected. Electrochemical behaviors of the composite films were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It showed that the potential, polymerization time and the kind of dopants had a great influence on CV, EIS performance and surface morphology. The PPy film absorbed on the modified electrode is resistent and has a smaller impedance value.In addition, graphene loaded with CuO nanoparticles was prepared by liquid phase method using DMF, 1-hexanol, isopropanol as solvents. The structure was characterized and the reaction mechenism was discussed. The results showed that CuO nanoparticles with sizes of 5-10nm were well dispersed on the graphene thin film which would combine with CuO by hydrogen bonding or coordination interaction between oxygen-containing functional groups and nanoparticles...