The Preparation, Characterization And Photocatalytic Performances Of The Bismuth-and Titanium-based Heterostructure Mateirals

Before1970s, contious deterioration of environment pollution and energyshortage indicate a potential global crisis. To achieve the sustainable development ofthe human society, it is imminenet to develop pollution-free technologies ofenvironmental remediation and search alternative clean energy. Nano simiconductphotocatalytic technology is a pormising ways among the green earth and renewableenergy projects. In this thesis, accroding to the respects that affect thenanophotocatalyst activity we develop a series of environment-friendly simulatedsunlight derived photocatalysts by using the green technology in the process ofpreparation. Moreover, the photocatalysts were used to remove Pharmaceutical andPersonal Care Products （PPCPs）. After optimizing the technics condictions ofelimination the target compound, we will provide the valid data to extend theapplication of photocatalytic technology in refractory wastewater.BiVO₄possessing different morphologies have been selectively synthesized by asimple procedure that based on an L-cysteine-assisted hydrothermal approach. Novelmorphologies of the BiVO₄microstructures such as bone-like, bowknot-like andnanorod structures have been successfully obtained by controlling the pH value of thereaction solution. It is worthy to note that the obtained monoclinic scheelite BiVO₄（m-BiVO₄） sample prepared at pH1.0possesses a bone-like microstructure, widenedband gap and exhibits enhanced sunlight photocatalytic performance in thedecomposition of ofloxacin （OFL） antibiotic. The effect of pH on the morphology,crystallinity and optical absorption property of BiVO₄were investigate, also thedifference of the prepared photocatalysts in removing the OFL were discussed indetali.The Ag/BiVO₄nanocomposite were prepared by using photochemical reductionmethod deposited Ag on the surface of BiVO₄as prepared pH1.0. Further discussionthe kinds of technics condictions on elimination the OFL molecule effectively, forexample the loading of Ag, dosage of the catalysts, pH, concentration and theirradiation time of OFL. The results indicate after irradiation60min under simulatedsunlight the highest degradation on OFL was achieved99..6%by loading of Ag0.6wt%and using1.5g L-1photocatalyst, under the concentration of OFL is10mgL-1and pH7.0. In this thesis, the enhanced photocatalytic activity was investigatedon these factors. The In₂S₃/BiVO₄composites were prepared by using one-step L-cysteineassistant hydrothermal synthesis. The morphology, structure, composition, and opticalproperty were characterized and the photocatalytic activity was evaluated bydegradation of rhodamine B dye and salicylic acid. The effect on photocatalyticactivity were investigated by the factors of the preparation time and temperature, theloading of In₂S₃, initial pH value. The results show the photocatalyst with dopingbetween5.0to10wt.%, the initial reaction solution pH1.0after the treatment of160oC24h in the high-pressure reactor exhibit the best activity. The bandgap was reducedto2.4eV after introduction wide bandgap in the BiVO₄composites. The enhancedphotocatalytic activity is attributed to the enlarged absorption of the spectrum andrestricted recombination action between electron and hole pair.In₂S₃/TiO₂nanocomposites are prepared by hydrothermal method combined withtemperature programming technique with the tetrabutyl titanate as raw material in thedifferent conditions （pH, dopings, reaction time and temperature） and characterizedby TEM, XRD, XPS and UV-Vis for the morphology, crystal structure, dopingmethods and optical properties. We used salicylic acid and Ofloxacin asrepresentative of PPCPs and researched the degradation activity under the simulatedsunlight. The results show that the smaller diameter of particles doped In2O3, thehigher of photocatalytic efficiency. When doping10.0%In₂S₃, pH is1.0and reactiontemperature is160℃, the photocatalyst have highest activity to degradation of thesalicylic acid. However, the best one is5.0%dopings to remove ofloxacin. Thedifferent contribution to photocatalytic activity was discussed compared toIn₂S₃/BiVO₄nanocomposites. The results show the In₂S₃/BiVO₄is another excellentsunlight-driven photocatalyst.