Preparation,Modification And Photocatalytic Activity Of TiO₂ With Surface Heterojunction

With the rise and growth of the photocatalytic field,the research on semiconductor-TiO2 is being promoted.The research progress on TiO2 structure is also changing.The excellent catalytic performance of octahedral or decahedral anatase TiO2 has been favored by everyone.This structure is mainly composed of {001} facets,{101} facets,and {010} facets,and has a good electron-hole separation effect.However,this kind of structure still belongs to wide band-gap TiO2 and does not have the response characteristics under visible light.Therefore,we analyze various factors that are beneficial to the photocatalytic activity of TiO2.Based on this superior structural morphology,we have synthesized the crystal heterojunction TiO2 with Ti3+ self-doped.At the same time,with the support of the structural characteristics of the substrate TiO2,it was modified and optimized by metal,metal oxides to realize its photocatalytic activity in the visible light.In addition,we also comparatively analyzed various factors affecting the catalytic performance of these catalysts by using the synthesized catalysts for methylene blue degradation experiments,and conducted beneficial explorations for the development and application of these catalysts.The research content of this paper includes the following aspects:1.Ti3+ self-doped decahedral TiO2 crystal and hierarchical TiO2 nanospheres with surface heterojunctionUsing titanium powder as a titanium source and HF as a morphology control agent,a deep blue three-dimensional decahedral TiO2 and a hierarchical-structured TiO2 nanomaterial were obtained using a hydrothermal reaction.Degradation of methylene blue(MB)is an evaluation reaction for photocatalytic activity.The results show that the two structures of TiO2 have visible light photocatalytic activity,which is mainly attributed to the presence of oxygen vacancy structure defects and Ti3+with 3d1 electronic configuration.which is mainly attributed to the existence of certain structural defects in the TiO2 material.The new local energy bands are introduced in the forbidden band of TiO2,thereby expanding the optical response range.2.Noble metal(Ag,Au,Pt,Cu)modified decahedral TiO2 crystalSince the substrate decahedral TiO2 exposes a higher {101} facets and the noble metal particles are more likely to appear on {101} surface,thereby improving the e--h+ separation effect.The as-synthesized TiO2 was modified by vacuum photoreduction method.Experiments explored the effect of the loading of metal particles on the activity of TiO2 catalysts,and also compared the influence of different metals on the catalytic activity at the same loading.3.metal oxide(CuO,PbO2,Fe2O3)composite TiO2The unique structural features and high {001} surface exposure rate of hierarchical TiO2 nanospheres prompted us to conduct composite semiconductors through metal oxide loading.The multi-heterojunction structures formed by the combination of the self-crystal heterojunction and the external crystalline heterostructure greatly enhances the charge carrier separation effect,and subsequent photo-degradation experiments confirm this.