TiO₂-based Composite Photocatalysts Prepared By Template Method With Enhanced Photocatalytic Performance

Ti O₂is a kind of excellent semiconductor material.Because of its low cost,non toxicity,good chemical stability and simple preparation method,Ti O₂is used as a good photocatalytic material.Although Ti O₂has all the above advantages,due to its wide band gap?3.2e V?,low utilization of visible light and high recombination rate of photogenerated electron hole pair,the photocatalytic degradation efficiency of Ti O₂is low.In this paper,Ti O₂with special morphology and uniform structure was prepared by template method,and then composite photocatalyst materials were prepared by precious metal deposition and heterojunction construction.At the same time,a series of properties such as composition,morphology and photochemistry were studied.The main research work of this paper is as follows:Firstly,Ti O₂hollow microspheres were prepared by hydrothermal method and calcination method with carbon microspheres as templates and isopropyl titanate as raw materials,so as to regulate the morphology of Ti O₂.Then,the photocatalyst of g-C₃N₄/Ag/Ti O₂composite was prepared by deposition of noble metal Ag and compounding with graphite carbon nitride?g-C₃N₄?nanosheets obtained by secondary calcination.The experimental results show that the photocatalytic performance of binary Ag/Ti O₂is better than that of pure Ti O₂,and the performance of ternary g-C₃N₄/Ag/Ti O₂composite have been further improved.This is mainly due to the deposition of noble metal Ag and its combination with g-C₃N₄,which promote the separation of photogenerated carriers,broaden the visible light response range and improve the photocatalytic activity.Secondly,the metal organic framework MIL-125 was prepared by hydrothermal method with terephthalic acid and isopropyl titanate as raw materials,and then Ti O₂was prepared by self template synthesis of MOFs.By using the metal organic framework?MOFs?as the precursor,Ti O₂with regular morphology and large specific surface area was prepared on the basis of maintaining the original morphology of MOFs,Then,g-C₃N₄/Ti O₂composite photocatalyst was prepared by compounding with g-C₃N₄nanosheet obtained by second calcination.The experimental results show that the photocatalysis performance of g-C₃N₄/Ti O₂is much better than that of pure Ti O₂and g-C₃N₄,which is mainly due to the improvement of the specific surface area of Ti O₂and the adsorption performance of dye,In addition,through the heterojunction with g-C₃N₄,the visible light response range of Ti O₂is expanded,the recombination of photo generated carrier pairs is restrained,and the separation efficiency is improved.Thirdly,on the basis of the previous work,the heterojunction of Ti O₂derived from MOFs and Zn In₂S₄with narrow gap bimetallic sulfide was constructed by in-situ method.The results show that the photocatalysis performance of the composite is greatly improved,which is mainly due to the construction of heterojunction to expand the visible light response range of Ti O₂,inhibit the recombination of electron hole pairs,and improve the separation efficiency.