| With the progress of science and technology of the society,environmental contamination and energy shortage issues are increasingly prominent.As a promising technology to solve these problems,photocatalysis have been widely applied for its non-toxic and low-cost merits..Titanium dioxide（TiO2）is recognized as one of the most promising photocatalysts,two fatal drawbaks limit its utilization:wideband gap causinglimited light response range,and rapid photo-induced charges recombination.In order to solve these problems,this paper studied the construction of the heterostructured photocatalysts,obtaining the superior photocatalytic performance.（1）BiVO4/TiO2 nanocomposites were fabricated by a facile wet-chemical process,followed by the synthesis of TiO2 hierarchical spheres via hydrothermal method.The BiVO4/TiO2 nanocomposites were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,UV-Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy.The results showed that prepared TiO2 presented hierarchical spherical morphology self-assembled by nanoparticles and an anatase–brookite mixed crystal phase.The introduction of monoclinic BiVO4components retained the hierarchical structures and expanded the light response to around 510nm.Type II BiVO4/TiO2 heterostructured nanocomposites exhibited improved photocatalytic degradation towards methylene blue under visible-light irradiation,especially for the composite photocatalysts with atomic Ti/Bi=10,which showed double degradation rate than that of pure BiVO4.The enhanced photocatalytic mechanism of the heterostructured BiVO4/TiO2 nanocomposites was discussed as well.（2）Graphitic carbon nitride（g-C3N4）have attracted much attention towards applications in environmental photocatalysis.However,the fast recombination rate of photo-induced electron-hole pairs hinders the practical use of g-C3N4.C-TiO2/g-C3N4composite materials were characterized by X-ray diffraction,scanning electron microscope,transmission electron microscope,uv-visible diffuse reflection spectrum and X-ray photoelectron spectroscopy.The results showed that the prepared C-TiO2/g-C3N4 composite was a porous composite material,and XPS proved that the heterojunction structure formed between C-TiO2 and g-C3N4,which improved the separation of photoionization charge.By ESR test,found that under the condition of light C-TiO2/g-C3N4 composite materials than those produced by the body than the quantity of oxygen free radical increase significantly,and through the light of the catalytic enhancement mechanism test,The enhanced superoxide radicals（·O2-）evolution improve the photocatalytic performance of C-TiO2/g-C3N4 towards organic pollutants（2,4-Dichlorophenol,Ciprofloxacin,Methyl Orange and Rhodamine B）removal.The heterostructured photocatalyst can work as a promising candidate to apply in solar-to-chemical energy conversion,and the synthetic strategy gives ideas for the design of MXene involved photocatalysts.The performance of TCN-5%is the best catalytic performance.（3）Bi4NbO8Cl was firstly prepared by a molten-salt method,and Bi/Bi4NbO8Cl composite was prepared by reducing by NaBH4.Due to the formation of heterojunction,photo-inducedcharge separation is promoted in Bi4NbO8Cl semiconductor,which provides more efficiency in photocatalytic performance for organic decomposition,and can be widely used in water purification.In addition,the number of oxygen vacancy（OVs）were increased during the synthesized procedure.OVs assisted oxygen activation to produce superoxide radicals（·O2-）,which promoted the photoinduced electron consumption and left more holes in the valence band of Bi4NbO8Cl,and the degradation rate of Rhodamine B（Rh B）was significantly enhancedthan that of Bi4NbO8Cl.Through the synergistic effect of Bi and OVs,the photocatalytic performance of Bi/Bi4NbO8Cl on methyl orange,p-nitrophenol,ciprofloxacin,2,4-dichlorophenol and other organic water pollutants was also improved. |
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