Modification And Photocatalytic Performance Of Bismuth-Rich Bismuth Oxyhalides

Bismuth oxyhalides BiOX?X=Cl,Br,or I?are a unique and promising group of recently developed advanced photocatalytic materials.They have been widely applied in several areas including the generation of H₂ by splitting water,decomposition of organic and inorganic pollutants in both wastewater and polluted air,and organic synthesis through harvesting the energy of light.The electronic structure of bismuth-based semiconductors confers them with a suitable band gap for visible-light response and a well-dispersed valence band composed of hybrid orbitals of Bi_6s and O_2p,making them a promising candidate when compared to other metal oxide semiconductors.In addition,they are simple to operate and prepare with controlled morphologies,making them attractive as potential photocatalysts.This thesis mainly consists two chapters as fllows:?1?In this investigation various Bi₁₂O₁₇Cl₂ samples were synthesized through an ethylene glycol-solvothermal protocol at variable calcination temperatures and subsequently characterized by X-ray diffraction patterns?XRD?,ultraviolet-visible spectrophotometer diffuse reflectance spectra?UV-Vis DRS?,scanning electron microscope?SEM?,and X-ray energy dispersion spectroscope?EDs?.The effect of calcination temperature on microstructures,band structures and sonocatalytic capability of as-prepared samples was discussed.In addition,other reaction dependant factors such as ultrasonic power,catalyst dosage,and reaction temperature were investigated.Based upon hydroxyl radicals detection,a possible sonocatalysis mechanism was primarily prospected.The cycle tests certifies potential application value of ultrasonic catalytic degradation of wastewater containing organic pollutants.?2?By comparing glycol-solvent hot method and hydrolysis of hydrolyzing BiCl₃,the Bi₁₂O₁₇Cl₂ hydrolysis of hydrolyzing BiCl₃ shows higher photocatalytic performance,at the same times the hydrolysis of hydrolyzing BiCl₃ is simple and easy to prepared compound semiconductor.Therefore,we successfully synthesized Ag/AgCl/Bi₁₂O₁₇Cl₂by using one-pot hydrolyzing BiCl₃ for the first time.The characters of Ag/AgCl/Bi₁₂O₁₇Cl₂nanoparticles were discovered by the X-ray diffraction patterns?XRD?,X-ray photoelectron spectroscopy?XPS?,scanning electron microscope?SEM?,X-ray energy dispersion spectroscope?EDS?,X-ray energy dispersion spectroscope?TEM?and ultraviolet-visible spectrophotometer diffuse reflectance spectra?UV–vis DRS?.The photocatalytic activity and stability of the as-prepared photocatalysts were evaluated by the photocatalytic degradation of RhB,MO and TC under visible light irradiation??>420 nm?.The enhancement of photocatalytic activity could be ascribed to the higher separation of electron-hole pairs compared with the bare Bi₁₂O₁₇Cl₂,fully using the high oxidization of the hole in the valence band of Bi₁₂O₁₇Cl₂.Finally,a possible photocatalytic mechanism was proposed by active species trapping experiments.The cycle tests certifies potential application value of photocatalytic degradation of wastewater containing organic pollutants.