Study On Synthesis And Photocatalytic Performance Of TiO₂ Modified With Acetylacetone

Nano-TiO₂ has become the most widely used multiphase photocatalyst in the field of environmental photocatalysis due to its unique physical and chemical properties,such as cheap,non-toxic,good thermal and chemical stability,high specific surface area,strong photogenerated hole oxidation ability and so on.However,the photocatalytic activity of TiO₂ can only be excited by ultraviolet light and the recombination rate of photogenerated carriers is high in the process of photocatalysis,which limits the efficient utilization of sunlight and the practical application of TiO₂.In order to deal with the above problems,the TiO₂ photocatalyst was modified by surface adsorption with acetylacetone in this paper to expand the visible light absorption range of TiO₂ and improve the utilization efficiency of light quantum.The main research work is as follows:（1）Using titanyl sulfate as a titanium source,a series of nano-TiO₂ photocatalysts（ACT-X）with surface carbon species and surface oxygen vacancy defects were prepared by simple dipping-roasting method.After modified with acetylacetone,caused the increase of oxygen vacancy defects on the surface of TiO₂,meanwhile,the residual carbonized carbon-oxygen species formed surface modification on TiO₂.When carbon species and surface oxygen vacancy defects coexist on the surface of TiO₂,resulting in the narrow of the band gap,the expansion of the light response range,meanwhile,promoted the separation of photogenerated charge carriers.In addition,surface carbon species can also further enhanced the visible light catalytic activity through photosensitization pathway.The prepared catalysts exhibited high photocatalytic degradation efficiency for phenol and methyl orange.Moreover,photogenerated hole（h⁺）are the main species during the photocatalytic degradation process.（2）Acetylacetone modified TiO₂（TA-400）was prepared by in situ synthesis method.The addition of acetylacetone not only can cause defects,but also greatly changed the morphology characteristics of TiO₂.After heat treatment at 400℃,carbonate-like structures were formed in the three samples,along with C-O,C=O and other carbon-oxygen species.The synergistic effect of oxygen vacancy defects and multiple types of carbon species,on the one hand,caused the VB tail extended,the band gap narrowed,the visible light absorption range expanded,and on the other hand,promote the separation of photogenerated charge carriers.Finally,based on the activity evaluation experiment and a series of characterization analysis results,the mechanism of enhancing the photocatalytic performance of TA-400 was proposed.