| In recent years, the semiconductor photocatalytic technology has attracted much attention because of its potential application in clean environment, water splitting and green organic synthesis and so on. TiO2 has become a photocatalyst for the extensive semiconductor because it is cheap, easy preperation, non-toxic, high chemical stability, strong anti-lightcorrosion etc. However, there are two major barriers limit the widespread use of TiO2 in the photocatalytic process:on the one hand, TiO2 has a relatively large optical band gap, it only absorb UV photons(less than 387nm); on the other hand, TiO2 has a low light quantum efficiency on account of the fast recombination of photogenerated electrons and holes. In order to solve the above problems, the researchers take the many different methods, such as doping with metal and nonmetal ions, modified with noble metals the combined with the newly carbon-based nanomaterials with unique structures, such as c carbon nanotube s, graphene oxide and graphene, coupled with other semiconductors, including Bi2WO6, WO3 and CdS, and so on, to improve the visible application and photocatarytic reaction quantum efficiency.Therefore, this paper used TiO2 as matrix, constructed different structure and morphology of TiO2 nanocomposite photocatarytic materials by selecting different compound phases. The samples were characterized by XRD, SEM, TEM, UV-Vis, IR and XPS analysis means, and tested the performance of photocatalytic degradation of organic pollutants, and explored the different compound phases on improving TiO2 light catalytic performance. The main research results are as follows:(1) TiO2/graphene/TiO2 three-layer core-shell structure composite photocatalyst were synthesized via a simple controlled hydrolysis method using tetrabutyl titanate as titanium source, the results are as follows:TiO2 core material particle size is about 800nm, TiO2 particle size of the outermost layer is about 30-50nm. The effect of different TiO2 loading on the photocatalytic performance was studied, TiO2/graphene/TiO2 three-layer core-shell structure composite photocatalyst prossessed the excellent photocatalytic degradation of methyl orange.(2) Reduced graphene oxide wrapped hollow TiO2 core-shell structural nanospheres were successfully synthesized via controlling the hydrolysis of tetrabutyl titanate and the surface reaction method, in which using SiO2 NSs as templates. Hollow TiO2 sphere with a diameter is about 350-400nm, about 15 nm in thickness, the outermost layer of graphene thickness is about 5nm. Photocatalytic experiments showed that, the introduction of reduction of graphene oxide, greatly improved the photocatalytic performance of the samples.(3) MoS2/TiO2 composite photocatalylic materials were successfully synthesized via two-step hydrothermal method using P25 as the titanium source. TiO2 nanobelts are of up to hundreds of micrometers in length and 50-150nm in width. When the suitable MoS2 nano particles loading on the surface of TiO2, can increas the specific surface area of photocatalyst, the adsorption of organic pollutants in the dark reaction process is enhanced; on the other hand, MoS2 nanoparticles supported on TiO2 surface and formed a heterogeneous structure, effectively promoted the separation of photogenerated electron-hole pairs, so as to improve the photocatalytic performance.(4) MoO3/TiO2 composite photocatalylic materials were successfully synthesized via hydrothermal and calcination process using P25 as the titanium source. MoO3 nanosheets grew along TiO2 nanobelts and formed a three-dimensional heterostructure. MoO3/TiO2 composite photocatarysts possessed the highest photocatalytic activity than that of pure TiO2 nanobelts and MoO3 nanosheets, since the interface of MoO3/TiO2 heterogeneous structure formed Ti-O-Mo bond, the electron can be transferred directly from the valence band of TiO2 to the conduction band of MoO3, expanded the light response range of samples. |
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