Preparation And Characterization Of Rutile Titanium Dioxide Supported Nano TiO₂ Composite Photocatalyst

Nano-TiO₂has excellent properties of photocatalytic degradation of pollutants and photocatalytic hydrogen production.The energy band coupling of nano-TiO₂with other semiconductors and loading on the carrier surface are important ways to improve the photocatalytic performance and solve the problems of difficult recovery when it is applied in water.Among them,the composite photocatalyst with carrier loading function and band coupling with nano-TiO₂to optimize the photo generated carrier transport behavior has research potential because it can form the dual role of improving the application performance of nano-TiO₂.Based on this background,we choose submicron rutile titanium dioxide（R-TiO₂）as carrier,and prepare nano-TiO₂（n-TiO₂）by mechanical attrition and sol-gel method respectively.The structure,morphology,energy and relative mechanism of the composite photocatalyst（R-TiO₂/n-TiO₂）were studied.Composite photocatalysts characterized by uniform loading of n-TiO₂on R-TiO₂surface were prepared by dry and wet mechanical grinding of R-TiO₂and n-TiO₂.Among them,the reasonable loading ratio of n-TiO₂of R-TiO₂/n-TiO₂prepared by dry method and wet method is50%and 30%respectively.The degradation rate of methyl orange of R-TiO₂/n-TiO₂prepared by dry method and wet method is 98%after ultraviolet irradiation for 30 min and 20 min respectively,which is equivalent to pure nano-TiO₂（P25）,and has good recycling performance.The chemical properties of R-TiO₂and n-TiO₂in wet grinding composite photocatalyst were combined at the interface.The n-TiO₂composite photocatalyst（R-TiO₂/n-TiO₂）prepared by sol-gel method on R-TiO₂surface and its properties were studied.In the R-TiO₂/n-TiO₂structure,n-TiO₂particles are about10 nm and loaded on the surface of R-TiO₂particles.The results show that R-TiO₂/n-TiO₂is superior to R-TiO₂and n-TiO₂in degradation of methyl orange under ultraviolet light,and the degradation rate of methyl orange is 90%and 100%respectively under 20 min and 30 min illumination.TEM showed that there was an obvious N-N homomorphic heteromorphic junction between R-TiO₂and n-TiO₂.The mass ratio of anatase in R-TiO₂/n-TiO₂is about 33.7%.The photocatalytic mechanism of R-TiO₂/n-TiO₂composite photocatalyst prepared by sol-gel method was studied.Photoelectrochemical tests and PL spectra show that the separation efficiency of photogenerated electron hole of R-TiO₂/n-TiO₂is better than that of R-TiO₂and n-TiO₂.The relative positions of conduction band and valence band of R-TiO₂and n-TiO₂in the composite photocatalyst were obtained by UV Vis DRS and MS.It was inferred that N-N homomorphic heteromorphic junction was formed in R-TiO₂/n-TiO₂,which was the main internal mechanism for the improvement of photocatalytic performance.