| Titanium dioxide due to its chemical stability, non-toxic and low cost advantages have widely application prospects in the field of photocatalytic and electrochemical activity. However, TiO2is an n-type semiconductor with a wider band gap can absorb UV light below the wavelength of387nm and the higher rate of photo-electron and hole recombination limited its photocatalytic application.In the technical field of photocatalysis, recovery of catalyst particles from treated water needs more manpower and material resources. Therefore, the research and development of photocatalyst with easy separation and recovery,and the response of visible light to improve solar energy utilization become a key issue in the study of photocatalytic. Due to the relatively low conductivity andthe slow lithium ion transmission rate and other shortcomings, the actual production application of TiO2is restricted.In chapter2, graphene oxide was prepared from purified natural flake graphite by the modified Hummers method. A series of composites of rutile TiO2with graphene (rGO-TiO2) were synthesized via a one-step hydrothermal reaction using graphene oxide and titanium isopropylate as raw materials. The influence of different dosages of graphene oxide on the photocatalytic activity of rGO-TiO2was studied. The obtained rGO-TiO2photocatalysts were characterized by X-ray diffraction pattern (XRD), Brumauer-Emmett-Tller (BET), scanning electron microscopy (SEM), Raman spectroscopy (Raman), transmission electron microscopy (TEM), UV-vis absorbance spectra and photoluminescence spectra (PL). The TiO2in composites is rutile phase with the needle cluster structure, and uniformly dispersed on the graphene sheets. The composites possess higher specific area compared to the pure rutile TiO2. The effect of the composites on the degradation of Rhodamine B and methyl orange under the ultraviolet light and visible light was studied. The results showed that as-prepared rGO-TiO2composite exhibited the best photocatalytic effect when the concentration of graphene oxide was0.5mg·mL-1. In chapter3, TiO2nanoneedle/graphene (TiO2/G) composites with a unique one dimensional/two dimensional (1D/2D) hybrid nanostructure were prepared via a facile hydrothermal route. These obtained rutile TiO2nanoneedles with lengths of about500nm have a homogeneous dispersion on the interlayers of graphene nanosheets. Compared to pure rutile TiO2, these TiO2/G hybrids exhibited the superior Li storage properties with good cycling stability (over94%capacity retention) and remarkable rate performance (149mAh g-1at a5C rate). These improved electrochemical performance can be attributed to the unique hybrid structure. On the one hand,1D nanoneedles could shorten the length of Li+transport paths to give the high Li+diffusion rate. On the other hand,2D graphene sheets could provide good electronic contacts to reduce the contact resistance, as well as keep the structural integrity of electrode materials.In chapter4, Fe3O4was prepared by solvothermal method, magnetic photocatalysts (Fe3O4/TiO2) were prepared using Fe3O4as support. The surface morphology and crystal pattern were investigated by XRD, SEM and UV-vis diffuse reflection, respectively. The best photocatalytic degradation condition was educed through the study of the initial concentration of pollutants, the amount of catalyst and the pH of solution. |
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