| Currently,photocatalytic reactions with visible-light-responsive photocatalysts have been shown to be highly efficient for the degradation of organic pollutants such as antibiotics,and have gradually replaced traditional degradation methods such as physical adsorption as the mainstream organic pollutant degradation pathway.Photocatalysts are essential for photocatalytic reactions,and bismuth-based materials have shown high photocatalytic activity in the degradation of antibiotics due to their matter energy band structure and high efficiency of light utilization.In this research,a variety of binary/ternary composite photocatalysts were synthesized based on bismuth oxyhalides that can be made visible-light-responsive.The synthesized photocatalysts were also used for the photocatalytic degradation of ofloxacin（OFL）and tetracycline hydrochloride（TCH）and the photocatalytic activity of the composite photocatalysts was evaluated by the photocatalytic reaction efficiency.The synthesized photocatalysts were characterized and analyzed by XRD,SEM,XPS,UV-Vis DRS and photoelectrochemical analysis,and the photocatalytic degradation mechanism of each binary/ternary composite photocatalyst for OFL and TCH was explained.The study and results of this thesis are as follows.（1）SiO2/BiOCl（SBC）,SiO2/BiOBr（SBB）,BiOCl/BiOBr（BBC）,SiO2/BiOCl/BiOBr（SBBC）,and E-BiOCl/BiOBr（E-BBC,synthesized by partial etching of SBBC samples）composite photocatalysts were prepared by microwave-assisted mixed solvent thermal method.The results of specific surface area and pore size analysis showed that the pore volume,pore size and specific surface area of SBBC and E-BBC samples were enhanced to a certain extent compared with those of BBC samples without the introduction of mesoporous SiO2microspheres.The results of the photoelectrochemical analysis showed that the ternary composite photocatalyst SBBC had higher photogenerated electron-hole pair separation efficiency compared with the binary composite photocatalysts SBC and SBB.the SBC,SBB,SBBC and E-BBC had extremely high activities for OFL and TCH,and the photocatalytic activities of SBBC and E-BBC samples were significantly higher compared with those of BBC samples.The effects of different SiO2contents on the photocatalytic performance of SBC samples were further investigated,and it was determined that the photocatalytic activity of SBC samples was strongest when the Si/Bi molar ratio was 1:1.（2）Binary composite photocatalysts of SiO2@BiOCl（SBC）and SiO2@BiOBr（SBB）were prepared by the mixed-solvent thermal method.The effects of different mixed solvents,solvent thermal temperature and PVP dosage on the photocatalytic performance of the SBC samples were investigated in the co-mixed system,and the optimal synthesis conditions for the preparation of SBC samples were determined by using ethanol-water as the mixed solvent thermal system,160°C as the mixed solvent thermal temperature and 0.2 g of PVP.The g-C3N4@SiO2@BiOCl（CN@SBC）and g-C3N4@SiO2@BiOBr（CN@SBB）samples were further prepared by introducing g-C3N4into the SBC and SBB samples,respectively,by the mixed solvent heat method.It was found that the band gaps of the ternary composite photocatalyst CN@SBC and CN@SBB samples were significantly narrowed,the recombination efficiency of the photogenerated electron-hole pairs was significantly reduced,and the photocatalytic activities for OFL and TCH were substantially enhanced after the introduction of g-C3N4.（3）The 2H-Mo S2@SiO2@BiOCl（MS@SBC）and 2H-Mo S2@SiO2@BiOBr（MS@SBB）ternary composite photocatalysts were prepared by a hybrid solvothermal method.It was found that the band gaps of MS@SBC and MS@SBB samples were narrowed and the recombination efficiency of photogenerated electron-hole pairs was reduced after the introduction of 2H-Mo S2.The photocatalytic degradation experiments demonstrated that the samples modified by 2H-Mo S2had higher dark reaction adsorption performance and photocatalytic degradation performance.（4）Cd S@SiO2@BiOCl（CS@SBC）and Cd S@SiO2@BiOBr（CS@SBB）ternary composite photocatalysts were prepared by ultrasonic-assisted hydrothermal method.It was found that the recombination rate of photogenerated electron-hole pairs was effectively reduced by constructing p-BiOX/n-Cd S heterostructures.The photocatalytic degradation experiments showed that the dark reaction adsorption efficiency and photocatalytic degradation efficiency of CS@SBC and CS@SBC samples for OFL and TCH were higher compared with those of SBC and SBB samples. |
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