Construction Of TiO₂-ZrTiO₄ Based Heterostructure Photocatalytic Materials And Its Performance Regulation

Titanium dioxide(TiO2)is an N-type semiconductor material with a wide band gap,and its band gap can reach 3.2 eV,which makes it need more energy when excited by solar energy,so it can only react under ultraviolet light.At the same time its low photogenerated carrier mobility seriously limits its practical application.In this research,using the TiO2-ZrTiO4 photocatalyst as the research object,the ZrTiO4 is obtained by in-situ growth,and the closely bonded TiO2ZrTiO4 heterogeneous interface is formed by semiconductor recombination.Then,the core-shell structure is constructed by introducing TiO2 substrate,which induces the growth of TiO2-ZrTiO4-SiO2 along the substrate and constructs the homogeneous/heterogeneous structure of TiO2/TiO2-ZrTiO4-SiO2.In addtion,Bi2O3-TiO2-ZrTiO4-SiO2 with type p-n/Ⅱ double heterojunction is constructed by compounding Bi2O3 to optimize the photo-generated carrier migration of the material and obtain the high-performance photocatalytic material.The relationship both process,structure and properties of TiO2-ZrTiO4-based photocatalytic material is explored by analyzing the changes of the material’s micro-morphology,elemental composition and photoelectric properties.The main results are as follows:(1)Using ZrOCl2·8H2O as the source of ZrO2,the formation of ZrTiO4 is carried by hydrothermal method,and the TiO2-ZrTiO4-SiO2 type II heterostructure photocatalytic material is successfully synthesized.The design idea of generating ZrTiO4 to improve the interface combination of TiO2 and ZrO2 and constructing type II heterojunction is proposed.The results show that the construction of heterostructure can effectively improve the separation rate of photogenerated carriers.In addition,the oxygen vacancies generated by the formation of TiO2/ZrTiO4 heterointerface can effectively reduce the energy required for the electronic transition,thus broadening the photoresponse range of the material.By adjusting the filling ratio,hydrothermal temperature and other factors,the degradation efficiency of TZS-3 on 15 mg·L-1 RhB can reach 98.9%after 50 mins of visible light irradiation,almost achieving the effect of complete degradation.(2)On the basis of TiO2-ZrTiO4-SiO2(TZS),a double heterojunction(homogeneous/heterojunction)photocatalytic material with core-shell structure of TiO2/TiO2-ZrTiO4-SiO2 is constructed by introducing porous sponge-like(rod-like)TiO2 substrate,and the mechanism of interface homogeneous junction is studied.The results show that,because of the excellent chemical compatibility of TiO2 substrate and TiO2 in TZS and different energy band structures,the interface homogeneous junction is effectively constructed and the electron migration at the interface is facilitated.At the same time,the introduction of TiO2 substrate allows the material to use it as a template to induce growth into a regular core-shell structure,which increases the surface area of the material.As a result,the material has good adsorption capacity,and more active sites are arranged on the surface of the material,and the utilization rate of visible light is greatly improved.TiO2/TiO2ZrTiO4-SiO2(PTZS)has a unique pore structure that leads to the aggregation of TZS particles,resulting in the inhibition of its own growth,which is not conducive to the reaction of TiO2 with ZiO2 to generate ZrTiO4.In this experiment,by adjusting the substrate morphology,the introduction amount,the hydrothermal temperature and other factors,the double heterojunction is successfully constructed and the utilization rate of visible light is further improved.The degradation rate of PTZS-2 and PTZS-5 to 15 mg·L-1 RhB reaches higher than 95%when exposed to visible light for only 30 mins,and the cycle stability is still good after three cycle tests.(3)Bi2O3-TiO2-ZrTiO4-SiO2 double heterojunction photocatalytic material of type p-n/Ⅱ is constructed by introducing Bi2O3 and TiO2-ZrTiO4-SiO2.The results show that on the basis of type Ⅱ heterojunction TiO2/ZrTiO4,p-type semiconductor Bi2O3 is added to successfully construct Bi2O3-TiO2(p-n type heterojunction)heterojunction with built-in electric field,which effectively solves the problems of type Ⅱ heterojunction,further promotes the migration of photo-generated electrons and increases the carrier separation rate.Meanwhile,the formed flaky Bi2O3 is used as a support structure to effectively separate TZS particles and avoid agglomeration.With the increase of Bi source recombination amount,the photocatalytic performance shows a trend of increasing at first and then decreasing.When the molar ratio of the photocatalytic material is Bi:Ti:Zr=2:25:5,the degradation rate of 30 mg·L-1 RhB reached 98%after 100 mins of visible light irradiation,and the good photocatalytic performance is maintained after the cyclic experiment.