Study On The Preparation And Application Of Titanium Dioxidebased Photocatalysts

Among many photocatalytic materials,titanium dioxide is undoubtedly one of the most popular semiconductor material.It is cheap and has a lot of advantages such as environmental friendly.But titanium dioxide is a semiconductor with broad band gap and just responses to the ultraviolet light,which greatly reduces its application.Therefore,in the field of photocatalysis,it is particularly important to improve the photocatalytic performance of titanium dioxide.At present,there have been many methods used for modifidation of titanium dioxide,such as noble metal deposition,semiconductors coupling and element doping.At first,the Au@TiO₂ composite photocatalyst was prepared through the photoreduction method,and dodecane was used to simulate an oil pollutant.Then the photocatalyst was used for the effective photocatalytic degradation of pollutants under the simulated sunlight.The influences of diferent factors,such as irradiation time,Au loading,and pH,have been investigated and reaction conditions have been further optimized.The liquid products after the degradation reaction have been analysized through GC instrument（GC-MS）,and the possible reaction mechanism was put forward.Second,we have prepared the heterojunction photocatalyst of TiO₂/TiOF₂ through a two-step solvothermal route.The experimental results showed that the TiO₂/TiOF₂ heterostructure showed higher photocatalytic activity compared with the single TiO₂ or TiOF₂ either in photocatalytic degradation of organic dyes or in water splitting.Specific surface area,photocurrent and photoluminescence spectrum have been tested and the reasons for photocatalytic performance improvement of the TiO₂/TiOF₂ heterojunction have been analysized.The reseach results have shown that the superior photocatalytic activity of TiO₂/TiOF₂ could be attributed to the synergistic effect between TiO₂ and TiOF₂,which can suppress the recombination of electrons and holes.On the basis of the TiO₂/TiOF₂heterojunction photocatalyst,Pd nanoparticles have also been loaded and the photocatalytic performance has been further improved.According to the discussions and analysis of experimental results,the possible reaction mechanism has been put forward.Finally,TiO₂ nanosheets have been combined with the layered MoS₂ to synthesis the MoS₂/TiO₂ composite through a simple hydrothermal route.The experimental results have shown that,compared with the single TiO₂,the photocatalytic activity for water splitting of this composite has been improved significantly.In order to investigate the influence of transition metal doping,cobalt acetate and nickel acetate have been added in the preparation of photocatalysts,and the Co and Ni-doped MoS₂/TiO₂ composite photocatalyst were obtained respectively.Experimental results have shown that in water splitting hydrogen production,compared to the undoped MoS₂/TiO₂,the photocatalytic activity of doped photocatalyst has been improved significantly.Finally,on the basis of experiments and theory,the possible reaction mechanism has been put forward,and the reasons has also been discussed.