Preparation And Photoelectric Properties Of Graphene-based Nanocomposites

Graphene, as a new2D nanomaterial, is another major discovery after the ball rullerene, carbon nanotube. Because of its excellent physical and chemical properties, graphene has become one of the most popular materials since discovered in2004. In recent years, with the large consumption of non-renewable energy and the worsening ecological environment, the clean and renewable energies are urgent need, which force people to dedicate to the research and development of new energy devices. Super capacitor and solar cell, as new energy storage device and clean energy respectively, have been widely studied in recent years. In this thesis, based on graphene or graphene oxide (GO), a series of energy materials were prepared, and their capacitance and photovoltaic properties were studied. Main work as follows:1. Synthesis and capacitance performance of nickel sulfide/graphene oxide nanocompositeThe NiS/GO nanocomposite was synthesized by a hydrothermal process in presence of GO. The products as-obtained were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the NiS particles (50nm) distribute evenly on the sheets of GO in nanocomposite. The impedance and electrochemical property of the NiS/GO nanocomposite are studied by electron impedance spectroscopy analysis and cyclic voltammetry respectively. The results show that the introduction of the GO enhanced the conductivity of NiS/GO nanocomposite, and then improved the capacitive behavior of the NiS/GO nanocomposite. The galvanostatic charge/discharge measurement results indicate that the NiS/GO nanocomposite has a high specific capacitance (800Fg"1at lAg"1) and long cycle life (over1000cycles).2. Synthesis and photoelectric transformation of Ag/ERGO nanocompositeAg/ERGO (Electrochemical Reduction of Graphene Oxide) nanocomposite was electrodeposited on surface of indium tin oxide (ITO) glass by a cyclic voltammetry, with a three-electrode system:a ITO glass as the working electrode, a Pt wire as the counter electrode and a saturated calomel electrode as the reference electrode. The obtained nanocomposite was characterized by SEM, XRD and so on. The results indicate that the surface of Ag nanoparticle is uniformly wrapped by ERGO, and the size of Ag nanoparticle is much smaller than that of the Ag nanoparticle obtained without graphene oxide. The photoelectric transformation results indicate that the Ag/ERGO nanocomposite has satisfactory photovoltaic effect under the irradiation of UV-Visible light.3. Synthesis and photoelectric transformation of Ag3PO4/TiO2/GO nanocompositeAg3PO4/TiO2/GO composite film was achieved by three steps. First, the titanium oxide sol was obtained by using the method of sol-gel, and the TiO2/GO composite was obtained after the addition of the graphene oxide. Then, the Ag3PO4was synthesized by reaction of AgNO3with Na3PO4in glycol medium. Finally, the Ag3PO4/TiO2/GO composite was obtained by adding Ag3PO4into TiO2/GO mixture solution. Taking ITO glass as basement, the Ag3PO4/TiO2/GO composite film was prepared by the dipping-lifting in the Ag3PO4/TiO2/GO composite solution, and then calcining. The Ag3PO4/TiO2/GO composite film as-obtained was characterized by UV-Vis, SEM and XRD. The SEM results indicate that the graphene oxide sheets and Ag3PO4particles are evenly distributed on the surface of TiO2film. The photoelectric transformation results show that the Ag3PO4/TiO2/GO nanocomposite film has satisfactory photovoltaic effect.