Study On Preparation And Properties Of Polymorphic And Modified Titanium Dioxide Photocatalytic Materials

Since Fujishima et al.first discovered that Ti O₂ had the effect of photochemical water cracking,photocatalysis technology has been widely concerned in such fields as pollutant treatment and energy conversion.As the first semiconductor material to be applied in the field of photocatalysis,Ti O₂ has been continuously studied and applied in the direction of photoelectrocatalysis due to its characteristics of high photocatalytic efficiency,good chemical stability and abundant raw materials.However,as a wide-band gap semiconductor,Ti O₂ has the problem of no visible light response and high composite rate of electrons and holes.To solve this problem,it is of great significance for further research on the modification of Ti O₂ semiconductor photocatalytic materials.The modification methods mainly include the induction of intrinsic defects,the construction of heterojunction and the deposition of precious metals.In addition,the properties of nano-Ti O₂ materials in different dimensions are different.The study and modification of nano-Ti O₂ materials with multi-morphology not only improve the photocatalytic application potential of Ti O₂ materials themselves,but also lay a foundation for the study of other multi-dimensional photocatalytic materials.The main contents of this paper are as follows:1. To solve the problem that monomer Ti O₂ has no visible light response,we used hydrothermal method to prepare Ti³⁺and oxygen vacancy stabilized co-doping macroscopic Ti O₂ thin slices in dilute hydrochloric acid solution without the aid of any template,and its microscopic morphology is directional array nanorods.This part of experiment provides a new method for preparing Ti³⁺and oxygen vacancy co-doped titanium dioxide nanorods array.2. At present,there are many factors affecting the preparation of anatase titanium dioxide nanobelts by alkaline method and their morphology and properties are greatly affected.We systematically studied the experimental factors affecting the preparation of anatase Ti O₂ nanobelts by alkaline hydrothermal method.Such as titanium source,raw material ratio,hydrothermal conditions and heat treatment system,etc.,the optimal experimental conditions for preparation of anatase Ti O₂ nanobelts by alkaline hydrothermal method were obtained.3. On the basis of the second part,we reported the preparation methods and photocatalytic applications of Ti O₂/Ag/Mo S₂/Ag composite with small interface resistance,high carrier separation rate,high visible light photocatalytic activity.This kind of composite was obtained by hydrothermal reaction and silver ammonia reaction.The first floor of Ag nanoparticles on Ti O₂ nanobelts not only improve the surface roughness of Ti O₂ nanobelts,which is not only conducive to Mo S₂ evenly grow on the surface of Ti O₂ nanobelts,but also reduce the interface resistance of Mo S₂ and Ti O₂.Furthermore,the Ag nanoparticles loaded on the Mo S₂ nanosheets accelerated the transfer rate of electrons on the Mo S₂ substrate,and the photocatalytic efficiency of the nanocomposite was further improved by the surface local plasmon resonance effect of Ag nanoparticles.4. We report the preparation and application of Ag-deposited Ti³⁺self-doped blue Ti O₂ nanosheets. This part of the experiment includes two main contents:one is through sulfuric acid?H₂SO₄?and hydrofluoric acid?HF?corrosion to expose the internal Ti³⁺of Ti O₂ nanosheets,the second is from the perspective of bionics,which simulated the action of carrier proteins on the cell membrane?transport of materials inside the cell to the outside of the cell?,treated Ag nanoparticles deposited on the etched surface as carrier proteins,and transfer the electrons generated inside Ti O₂nanosheets to surface to participate photocatalytic reaction.In this way,Ag nanoparticles doped Ti³⁺self-doped blue Ti O₂ nanosheets solved the problem that Ti³⁺self-doped Ti O₂has good visible light response but has low photocatalytic efficiency.5. It is difficult to recycle powdered titanium dioxide photocatalyst,so we prepared Zn-doped Ti O₂ aerogel by sol-gel method. The gel soaked by tetraethyl orthosilicate?TEOS?can enhance its skeleton strength,in this way Zn-doped Ti O₂aerogel with low density and large specific surface area can be successfully obtained by drying at atmospheric pressure.This aerogel material has good adsorption and photocatalytic properties.In summary,this paper obtained one-dimensional Ti O₂ nanorods,nanobelts and two-dimensional nanosheets by hydrothermal method,and obtained Zn-doped Ti O₂aerogel by sol-gel method.In order to further realize their application under visible light,they were modified by the induction of intrinsic defects or the construction of hetero-junction.And we studied their application in photocatalytic reduction of Cr???and light degradation of organic dyes and discussed their mechanism of photocatalysis through appropriate test methods.