Research On Morphology Control And Photocatalytic Modification Of Iron Oxide-based Materials

Advanced Oxidation Processes（AOPs）that directly mineralize organic pollutants is an effective approach to solve the deteriorating water pollution environmental problems in recent years.As a typical AOP,the photo-Fenton reaction can achieve this goal by continuously generating strong oxidizing free radicals.α-Fe₂O₃ is an important photo-Fenton catalyst with the advantage of high stability,environment friendly,and abundant reserves etc.Therefore,the photocatalytic properties of iron oxide-based materials by the preparation of novel morphologyα-Fe₂O₃,composites and modified materials were studied.The main content of the dissertation is as follows.:（1）Using iron chloride as the iron source and EDA as the template agent,two novel morphologyα-Fe₂O₃ jagged spindle and tetrahexahedron were prepared by hydrothermal process.It was found that at lower temperature and high concentration of EDA the appearance of the resultingα-Fe₂O₃ is a jagged spindle with{10-12}dominated plane exposed,while a tetrahexahedron with{10-12},{11-22},{11-24}plane exposed at higher temperature.The rate constants of photocatalytic Fenton’s degradation of RhB are 0.0198 and 0.0120,respectively,which is much higher than that of the general spindleα-Fe₂O₃（0.0079）.（2）The flower-like and disorderedα-Fe₂O₃@TiO₂ core-shell composites were prepared on hexagonal nanoplates.The rate constant for the photocatalytic Fenton’s degradation of methylene blue was 0.0082 and 0.0141,significantly higher than the neat hexagonal nanoplates（0.023）,which may be related to the morphology of the composite and the crystal form of TiO₂;（3）The photocatalytic performance of hexagonal nanoplates,hexagonal bipyramids and rhombohedralα-Fe₂O₃ crystals with exposed specific surface areas and{0001},{10-12},{11-24}dominant planes were compared.The reaction rate constants were 0.0103,0.0027,and 0.0205 on degrading RhB,respectively.The degradation rate constants of hexagonal nanoplates and hexagonal bipyramids were increased to 0.0419 and0.0544 after vacuum annealing at 550°C,which may be attributed to the oxygen vacancies formed on the surface and micropores generated inside.（4）The morphology of Fe₃O₄ crystals was controlled using ferrous sulfate as the iron source and adjust the concentration of NaOH and NaAc during hydrothermal process.The cubes,octahedrons,rhombic dodecahedrons and a series of transitions between were synthesized respectively,and their photocatalytic performance was studied.