Modification And Photocatalytic Properties Of BiOBr Photocatalyst

With the rapid development of the social economy and the continuous deepening of industrialization,the random discharge of industrial waste water has caused the frequent occurrence of water pollution incidents.The problem of water pollution has already caused widespread concern.Various methods have been developed to solve the problem of water pollution.Among these methods,the technology of semiconductor photocatalys appeals peoples' concerns because of its environmentally friendly,low energy consumption,no secondary pollution and degradation completely.As the first element of photocatalytic technology,photocatalyst attracts widely concern from the researchers.As one of the semiconductor photocatalysts,BiOBr has been extensively investigated owing to its high photocatalytic activity,high stability,none toxicity and suitable band gap energy.But the photocatalysts' application was restricted for the high recombination between photo-generated electrons and holes.In this thesis,BiOBr was modified with constructing composites semiconductor and metallic ion doping.At present,modification of preparation methods is thought one of promising ways to improve the photocatalytic activity of the photocatalysts and the improvement of preparation methods has also aroused peoples'interest.Microwave chemistry has shown great advantages in the preparation of nanomaterials,especially in the preparation of functional materials with special structures and properties.Microwave-assisted methods have the advantages of high efficiency,time saving and energy saving.The detailed works are as follows:(1)In this dissertation,the NiO/BiOBr composite photocatalysts were successfully prepared by microwave-assisted method.The photocatalysts were characterized by X-ray photoelectron spectroscopy(XPS),X-ray powder diffraction(XRD),Scanning electron microscope(SEM),Energy-dispersive spectroscopy(EDS),UV-vis absorption spectroscopy(UV-vis).Compared to BiOBr and NiO,not only the morphology and structure but also the band gap energy all changed.In addition,the separation ability of photo-generated electrons and holes was improved.The photocatalytic activity of the catalysts was detected by degradation of RhB under the visible light.During the photocayalytic process,the catalyst of NiO/BiOBr=1:1.5 exhibits the highest photocatalytic activity.The photocatalysis mechanism of the NiO/BiOBr catalyst was detected.(2)In this paper,BiOI/BiOBr composits semidonductor photocatalysts were synthesized by microwave-assisted method.The photocatalysts were characterized by XRD,SEM,XPS,EDS,UV-vis,Fluorescence spectrum(PL).The results show the band gap energy and the light absorption range all chang greatly.The combination rate of the photogenerated electron-hole also was reduced.Under the visible light,the photocatalysts'photocatalytic activity was detected through the the process of degradation RhB.During the photocayalytic process,the catalyst of BiOI/BiOBr=1:2.5 exhibits the highest photocatalytic activity and stability.The results indicate that h+ and ·O2-are the dominant reactive radicals.(3)The catalyst of Co2+-BiOBr was prepared by microwave-assisted method.And the photocatalysts' photocatalytic activity was detected.The photocatalysts were characterized by XRD,SEM,PL,EDS,UV-vis,Fourier-transform infrared-spectroscopy(FTIR)and Inductive coupled plasma emission spectrometer(ICP-OES).After doping Co2+,the photocatalyst shows better photocatalytic activity.Not only the morphology and structure but also the band gap energy were changed.The combination of the photogenerated electron-hole was reduced evidently.The main reactive radicals are h+ and e-.