Preparation And Photocatalytic Properties Of Three Dimensional Mesoporous TiO₂ Nanomaterials

As a pioneer in the field of photocatalysis,TiO₂ based semiconductor photocatalyst has attracted much attention due to its high catalytic activity,mild reaction conditions,continuous and efficient catalysis and good cycle stability.Some of its own defects also limit its application to a certain extent.Structural control and semiconductor composite modification can improve the physicochemical and catalytic properties of materials to a certain extent.In this paper,CeO₂ and TiO₂ semiconductor were combined to form heterojunction structure,and hollow/mesoporous TiO₂nanomaterials were prepared by template method and hydrothermal synthesis method.The physicochemical properties and photocatalytic properties of different materials were characterized.The results are as follows:（1）Firstly,TiO₂ was coupling with CeO₂ to form heterojunction materials,and regulate the loading of CeO₂,select the optimum with best structure and performance.The results were as follows:（1）The CeO₂/TiO₂ nanocomposites possess rich pore structure and large specific surface area（76.9 m²/g）.The results of photocatalytic degradation of phenol showed that 0.5wt%CeO₂/TiO₂ had the best degradation efficiency.After 120 minutes of UV treatment,the phenol degradation rate reached99.1%,and hold near 94.0%after four cycles of experiments.（2）To further improve their performance,the zero dimensional TiO₂nanoparticles were upgraded to three-dimensional core-shell and hollow structure by template method.The RF spheres were prepared by the expanded St（?）ber method,RF@F127/TiO₂ core shell microsphere material were synthesized by sol-gel method.The hollow mesoporous spheres（HM-TiO₂）were obtained after two step calcination.Adjusting the parameters,the hollow mesoporous microspheres with the best performance were obtained,and the photocatalytic degradation of phenol was studied.The results show that the uniformly spherical,single dispersed RF microspheres were synthesized and the size of the microspheres was about 220 nm.The HM-TiO₂-SDS4hollow mesoporous microspheres were prepared with a uniform particle size of about250 nm and a specific surface area of 78 m²·g^-1.The results of photocatalytic degradation of phenol showed that HM-TiO₂-SDS4 had the best catalytic performance.After degradation for 110 min,the phenol degradation rate could reach 99.3%and remained at about 97%after four cycles.（3）The dendritic fiber-shaped three-dimensional mesoporous Si O₂ microspheres（DFNS）nanoparticles with central divergent channels were synthesized by one pot hydrothermal technique,adjusting a series of variables and selecting the optimal conditions,the microspheres with optimal structure were prepared.DFNS as core,F127/TiO₂ as the shell,the DFNS@m-TiO₂ core shell structure were futher synthesized by sol-gel method.The results are as follows:The as synthesized DFNS mesoporous silica spheres with folded structure and high specific surface and the particles were evenly distributed.The synthesized DFNS@m-TiO₂ core shell catalysts with complete anatase crystal and a high specific surface area of 525.3 m²·g^-1,the optimal material was selected by adjusting the amount of TBOT,and the degradation rate of phenol was 99.63%in 220 min.