Study On Preparation And Properties Of Metal Oxides Based Composite Materials

With the global economic development, a great amount of non-renewable energy is consumed, leading to severe resource depletion and pollution. To address these problems, attention has been paid to clean energy and processing of environmental pollution. Metal oxides, such as TiO2, CuO, et al, have become an important topic of research and have been applied in many related fields, because of their low cost, good stability and reliability, as well as facile syntheses procedures. However, their wide application is still limited by the intrinsic properties of metal oxides:weak catalytic activity, poor electrochemical activity and difficulty for recycling. Therefore, it has been realized that improving the activity and fabricating composite materials with metal oxides are important topics of research.In this thesis, we synthesized TiO2/reduced graphene oxide (rGO) nanocomposites using a facial one-step method, and studied their photoelectrochemical properties and hydrogen production performance. Furthermore, we synthesized copper oxide/reduced graphene oxide (CuO/rGO) nanocomposites measured their electrochemical performance as anode materials for lithium ion batteries. At last, Fe3O4@Cu2O/Ag composites were prepared, and their photocatalytic performance was further explored.The main contents are summarized as follow:1. A simple one-step sol-gel method with hydrothermal process was employed for preparing TiO2/reduced grapheme oxide (rGO) nanocomposites. This approach leads to the reduction of grapheme oxide and the growth of TiO2nanoparticles simultaneously without using any reductant or surfactant. The characterization of the as-prepared hybrid nanocomposites reveals that the TiO2nanoparticles were uniformly growth on the reduced graphene oxide sheets with highly dispersion. The growth process has been investigated and a possible mechanism is proposed. Photocatalytic experimental results indicated that the nanocomposites exhibit superior water splitting activity compared to bare TiO2nanoparticles. The photocatalytic performance could be obviously improved (about3.5times with pure TiO2and2.3 times with P25) for the hydrogen production after coupling1.0wt%rGO, the enhanced photocatalytic performance of TiO2/rGO nanocomposites is mainly attributed to excellent electron trapping and transportation properties of rGO which can leading to an effective charge anti-recombination and thus enhancing the photocatalytic activity.2. A facile hydrothermal procedure was applied to synthesize copper oxide/reduced graphene oxide (CuO/rGO) nanocomposites. The as-prepared CuO/rGO composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectra, FT-IR and TG. The results indicated that we’ve successfully synthesized a kind of three-dimensional (3D) mesoporous CuO nanorods and they were uniformly grown on the surface of rGO sheets. Moreover, the electrochemical properties and battery performance were studied. It found that these as-synthesized3D CuO/rGO nanocomposites not only provided appropriate contact area between electrode and electrolyte but also increased the electrical conductivity of the electrode, resulting enhanced electrochemical performance and high cycling stability for lithium-ion battery with the specific capacity of470mAh/g after50cycles.3. In this work, Fe3O4nanoparticles modified by L-cysteine were firstly prepared by a one-step partially-reduced method under mild conditions. Then, magnetic Fe3O4@Cu2O/Ag composites, self-assembled by nanosheets with an average thickness of150nm, were successfully synthesized via one-pot solvothermal approach in a glycol-ethanol system. The photocatalytic activity was evaluated by the photodegradation of methyl orange (MO) under visible light. It is found that the well-designed nanocompositephotocatalyst have a degradation rate of97.7%for MO within40min. Furthermore, the nanocomposites can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running5times, which present higher stability and efficiency than Fe3O4@Cu2O. The above results also indicate that Ag could suppress the photocorrosion behavior of nanocomposites and improve the photocatalytic activity of nanocomposites.