Synthesis And Application Of Porous TiO₂ By Single Micelle Self-assembly Strategy

Environmental pollution and energy shortage are the two major problems that hinder human survival.Renewable energy should be developed as soon as possible to solve these problems.Solar energy has many advantages,such as pollution-free,large reserves and so on.However,because solar energy cannot be used by people all the time.Due to the discontinuity of solar energy,it is difficult to apply it to real life.Converting solar energy into chemical resources as much as possible can make up for this deficiency.Solar energy can be converted into hydrogen energy.Because of its high efficiency and renewable advantages,hydrogen has become a green energy source that people want to develop.Among transition metal oxides,mesoporous TiO₂ has become an important porous semiconductor material in the past decades due to its wide range of physical and chemical properties,low cost,environmentally friendly process,and high specific surface area and large pore volume.In this thesis,mixed-phase mesoporous TiO₂ nanospheres prepare by a single micelle self-assembly method,and then the mesoporous TiO₂ is modified by post-loading or in-situ loading of transition metal oxides to improve the photocatalytic performance.The mesoporous TiO₂nanoflowers synthesizes by the single micelle self-assembly method,and their morphology is adjusted.We use a single micelle self-assembly method to synthesize mesoporous TiO₂ nanoflowers,and adjust their morphology.（1）Mesoporous TiO₂ is prepared by single micelle self-assembly method,and then modified with different other transition metal oxide composite nanomaterials by chemical impregnation method to construct Ni O/TiO₂,Co O/TiO₂,Cr₂O₃/TiO₂composite materials.Characterization and analysis by TEM and XPS show that the metal oxides are uniform Ly distributed on the surface of the mesoporous TiO₂.In the experiment,the organic dye Rh B is selected as the target degradation product,and the degradation ability of the catalyst to Rh B is studied under visible light.Under the same test conditions,the effect of loading of the same proportion of different metal oxides on the degradation of Rh B dyes is explored.The 3%Cr₂O₃/TiO₂composite catalyst has the best degradation performance and performance stability.This is mainly due to the introduction of Cr₂O₃,which changes the band gap size and energy band structure of the composite sample,expandes the absorption range of visible light,enhances its absorption capacity under visible light,and further produced more photo-generated electron-hole pairs.It promotes the migration rate of photo-generated carriers,greatly improves the photocatalytic activity of the catalyst,and promotes the migration rate of photo-generated carriers,so that its photocatalytic performance can be improved.（2）Ni₂P/TiO₂ composite catalyst synthesizes using single micelle self-assembly method to in situ load Ni O and phosphatization process..The phase and morphology of the composite are analyzed through a series of characterizations.The results show that the single micelle self-assembly strategy combined with in-situ loading and phosphating can construct a composite material with Ni₂P uniform Ly distributed on the surface of mesoporous TiO₂.A series of materials are tested for hydrogen production by photolysis of water.Among pure mesoporous TiO₂ and different ratios of Ni₂P/TiO₂ catalyst samples,the 3%Ni₂P/TiO₂ composite catalyst has good performance for photolysis of water and hydrogen production.the high photocatalytic efficiency of Ni₂P/TiO₂ composite material is due to the formation of nickel-oxygen bonds（Ni-O）that fixes Ni₂P on the surface of mesoporous TiO₂,which greatly improves light absorption and promotes the separation of electron-hole pairs produced.（3）The pure anatase phase petal-like mesoporous TiO₂ nanomaterials are synthesized using the single micelle self-assembly strategy combined with the secondary assembly.The morphology and crystal phase of mesoporous TiO₂ are adjusted,and the synthesis mechanism of petaloid mesoporous TiO₂ is discussed.In the process of forming ultra-thin mesoporous TiO₂ nanosheets,shear stress is added to make these ultra-thin single-layer two-dimensional mesoporous nanosheets secondarily assembled into petal-like mesoporous TiO₂.The petaloid mesoporous TiO₂ has an ordered mesoporous structure and a pure anatase crystal phase.This method provides a basis for the construction of new nanostructures.