Synthesis And Property Study Of BiOI-based Composite Photocatalyst

BiOI is a semiconductor material with layered structure,narrower band gap(Eg=1.8 eV)and higher chemical stability.It is also a very ideal photocatalyst with visible light responsiveness.Unfortunately,the rapid charge recombination of photo-induced electron and hole pairs has significantly limited its application.Numerous researches have proved that BiOI-based composite photocatalysts can effectively enhance its photocatalytic activity by inhibiting the recombination of photo-induced electron and hole pairs.In this thesis,four kinds of BiOI-based composite photocatalysts are prepared via microwave hydrothermal method.The structure and performance of the products are characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy(RAMAN),photoluminescence(PL),Fourier transform infrared spectrometer(FTIR)and UV-visible diffuse reflectance spectroscopy(UV-vis DRS).The photocatalytic properties of the photocatalysts are further evaluated by decomposing organic pollutants under visible-light irradiation and their possible photocatalytic mechanism of composite catalysts are also discussed.The main results and conditions are as follows,(1)The composite catalysts of BiOI and reduced graphene(GOr),BiOI/GOr-1 and BiOI/GOr-2 are synthesized via mechanically mixing method and one-step in situ microwave solvothermal method,respectively.The photocatalytic activities of BiOI/GOr-1 and BiOI/GOr-2 are evaluated by decomposing methylene blue(MB)and levofloxacin(LEV).It reveals that the experimental parameters such as preparation method,the doping amount of GOr,the pH of LEV solution and the amount of photocatalyst are crucial to the photocatalytic process.Excellent enhancement of degradation efficiency is observed for BiOI/GOr-2 photocatalysts under visible-light irradiation.(2)A new photocatalyst of BiOI modified γ-Fe2O3 magnetic composite is prepared for the of γ-Fe2O3/BiOI show that the degradation rates can reach 67.6%and 64.1%,higher than the pure BiOI 35%and 34.3%,respectively.(3)α-Fe2O3/BiOI heterojunction composite is successfully synthesized by microwave method.After visible light irradiation for 120 min,the degradation rate is 51.7%for MO and 65.3%for tetracycline(Tc),which can be due to the formation of p-n heterojunction between BiOI and α-Fe2O3.(4)BiOI-MWCNT composite is successfully prepared.It can remove 90.1%of MO in 60 min under visible-light irradiation.The presence of MWCNT significantly enhances its photocatalytic activity,which attributed to the MWCNT can inhibit the recombination of photogenerated electrons and holes pairs.