Preparation And Properties Of Inorganic Organic Hybrid Photocatalyst With Hollow Structure Titanium Dioxide

Clean energy（H₂,etc.）is an ideal alternative to fossil fuels.As an environmentally friendly green technology,photocatalysis can directly use sunlight to generate electrons and reduce water to H₂ under mild conditions.Meanwhile,photo-generated oxidizing radicals can degrade toxic pollutants into non-toxic products,thus improving the environmental quality.At present,titanium dioxide is one of the most active photocatalytic materials.However,its wide band gap（3.2 e V）and high electron-hole recombination ratio limit the practical application of photocatalysis.Therefore,it is still challenging to regulate the band gap of mesoporous titanium dioxide and the separation effect of electron-hole pairs to improve the photocatalytic performance.In this thesis,mesoporous titanium dioxide nanotubes were synthesized by a one-step solvothermal method.In addition,the hybrid photocatalysts were prepared with other organic semiconductor materials（MOFs,COF）.The photocatalytic performance was improved by improving the photoresponse range and the separation efficiency of electron-hole pairs.The main content of this thesis includes the following three parts.1、Porous mesoporous titanium dioxide nanotubes with large surface area were synthesized in a mixture of anhydrous ethanol,anhydrous ether and glycerol using titanium oxysulfate as the precursor.NH₂-Ui O-66/Ti O₂ hybrid photocatalytic material（NU/Ti O₂）was prepared by chemical deposition.To explore the photocatalytic NO₂oxidation of carbon soot particles by hybrid materials,NH₂-Ui O-66 has a certain NOx adsorption capacity.It can generate charge migration path from ligand to-coordination metal,showing excellent photocatalytic NO oxidation performance.Compared with the original Ti O₂,the synthesized20%NH₂-Ui O-66/Ti O₂（2-NU/Ti O₂）nanocomposites showed excellent NO₂photocatalytic carbon oxidation of soot particles(0.063μmol·h^-1·g^-1,99%N₂selectivity).The existence of NH₂-Ui O-66 nanoparticles reduced the Ti O₂ band gap from 3.2 e V to 2.87 e V,and the formed heterogeneous interface promoted charge separation and transmission.The photocatalytic removal of nitrogen oxides was thus improved.2、The TpPa-1-COF/TiO₂ nanotube hybrid was synthesized by the solvothermal method after the amino modification of the Ti O₂ surface.The covalent organic skeleton Tp Pa-1-COF is closely bonded with Ti O₂ through a covalent bond,which can significantly improve the photocatalytic hydrogen evolution activity.The photocatalytic hydrogen production rate of 30%Tp Pa-1-COF/Ti O₂(31.9 mmol·h^-1·g^-1)was increased by 2 times compared with Ti O₂.The introduction of Tp Pa-1-COF increases the specific surface area,expands the absorption range of light,reduces the band gap,and itsπ-πconjugated structure is conducive to electron transfer.The inherent porosity of Tp Pa-1-COF also provides more active sites for the composite,and the heterogeneous structure formed with Ti O₂ improves the separation efficiency of electron holes and promotes the transport of charge carriers,thus improving photocatalytic performance.3、Ag nanoparticles were loaded on the surface of TpPa-1-COF/Ti O₂ by UV reduction method.As electron acceptors,Ag nanoparticles promote the separation and transfer of photogenic charge,thus improving hydrogen production performance.The photocatalytic hydrogen production performance of the synthesized Ag/COF/Ti O₂ composite under AM 1.5G light was investigated.The photocatalytic performance of the 2%Ag/COF/Ti O₂ composite was the best,and the hydrogen production rate was 1.4 times higher than that of the COF/TiO₂ hybrid.