Modification And Photocatalytic Properties Of BiOX(X=Cl?Br?I)

In recent years,semiconductor photocatalysis technology has considered as the most promising method in resolving the problem of energy shortage and environmental pollution.The exploitation of high efficient visible light photocatalysts is the focus of current research.BiOX(X=Cl,Br,I)have high separation efficiency of photo-generated electrons and holes and also have strong absorption in visible light region.Cerium dioxide(CeO2),as an important rare earth metal oxide,is acknowledged as many advantages,such as physical and chemical stability,small size and cost-effectiveness.In this dissertation,we devote to research the consequence of coupling with other semiconductor and doping with nonmetal atoms of BiOX(X=CI,Br,I).A series of BiOBr/Ce02 composites were also synthesized by a simple solvothermal method.According to the results of XRD,SEM,PL,(UV-vis),X-ray photoelectron spectroscopy(XPS),high resolution transmission electron microscopy(HRTEM)and energy-dispersive X-ray spectroscopy(EDS),heterostructured BiOBr/CeO2 were successfully synthesized.The composites exhibit lower band-gap energy and agglomerated extent,stronger adsorbability and higher separation efficiency of photo-generated electrons and holes,which could enhance of photocatalytic activity.The BiOBr/Ce02 with moral ratio of 5:1 shows the best photocatalytic activity in photodegradation of rhodamine B(RhB),methylene blue(MB)and bisphenol A(BPA)under visible light irradiation.The active species trapping experiments shows that the holes(h+)and superoxide radical(·O2-)are the dominant active species in photodegradation process.In this dissertation,BiOX/CeO2(X=Cl,Br,I)composites were successfully prepared for the first time by microwave-assisted route.The samples were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),ultraviolet-visible absorption spectroscopy(UV-vis)and photoluminescence(PL)spectra.The rhodamine B(RhB)solution were chose to evaluate the photocatalytic activity of the samples under visible light irradiation,and all the composites show better photocatalytic activity.Furthermore,the proposed possible photocatalytic mechanism exhibits that the enhanced photocatalytic activities could be mainly attributed to the stronger adsorbability and lower recombination ability of photo-induced electrons and holes of the composite.A novel F-doped BiOCl photocatalysts were synthesized by hydrothermal method and only by using water as the solvent.The samples were characterized by XRD,XPS,SEM.TEM and UV-vis.The F-doped BiOCl with molar ratio of 3:4 performed the highest degradation rate and could degrade RhB solution completely after 35 min irradiation through a photosensitization pathway.The enhanced photosensitization performance of F-doped BiOCl could be attributed to the smaller crystallite sizes and enhanced the hydrophilic properties.