Preparation And Electrochemical Performance Of Metal Oxide-based Nanocomposite Materials

Metal oxide-based nanocomposite materials have shown promising application as electrode material for electrochemical sensors, fuel cell electrocatalysts, supercapacitors and lithium ion batters. Due to the structure sensitivity of electrode material, the controlled synthesis of metal oxide-based nanocomposites with designed structure, morphology and size is of critical importance to improve their electrochemical performance. In this thesis, we prepared three different kinds of metal oxide-based nanocomposite materials. The synthetic method, structure and electrochemical property of these materials and their application as electrochemical sensor and fuel cell electrocatalyst were investigated.(1) The Au-TiO2/graphene (GR) nanocomposite was prepared by deposition of Au nanoparticles (NPs) on TiO2/GR substrates. The as-prepared Au-TiO2/GR was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The presence of Au NPs on TiO2/GR surface remarkably improves the electrocatalytic activity towards the oxidation of hydrogen peroxide (H2O2) and β-nicotinamide adenine dinucleotide (NADH). The Au-TiO2/GR modified glassy carbon electrode exhibits good amperometric response to H2O2and NADH, with linear range of10-200mM and10-240mM, and detection limit of0.7and0.2mM, respectively.(2) Mesoporous CuO microspheres with core-in-hollow-shell structure were synthesized by one-pot hydrothermal method, using dicyandiamide as hydrolysis agent and poly(vinylpyrrolidone)(PVP) as soft template. The as-synthesized CuO microspheres were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and N2sorption measurements. The core-in-hollow-shelled CuO microspheres exhibit greatly enhanced amperometric response towards glucose as compared to that of the simple hollow counterpart. The as-developed nonenzymatic glucose sensor exhibited favorable performance with wide linear range (0.005-7.95mM), sensitivity of622.2μA mM cm-2and low detection limit of1μM.(3) The TiO2-C hybrid material was prepared by carbonization of the mixed precursor containing TiO2and melamine, and was used to support Pd nanoparticles for electrocatalytic formic acid oxidation. The as-prepared Pd/TiO2-C catalyst was characterized by XRD, TEM, HR-TEM, EDS, and electrochemical measurements. Pd nanoparticles deposited on the hetero interfaces of TiO2-C possess a large electrochemical surface area and exhibited enhanced activity and stability towards formic acid oxidation.