Effect Of Titanium Dioxide Modification On Photocatalytic Performance

Titanium dioxide nanomaterials are widely used in the treatment of environmental pollution,especially the degradation of organic pollutants in industrial wastewater because of its non-toxic,cheap,high chemical stability and photocatalytic activity.However,TiO₂has two major disadvantages in its own right:a large forbidden band width?³.2 eV?and a high recombination rate of electron-hole pairs,severely limiting its photocatalytic application.Hence,the effects of the modified TiO₂ nanomaterials prepared by different synthetic methods on their photocatalytic properties were studied in order to narrow their bandgap and effectively inhibit the recombination of photocarriers,thereby improve the photocatalytic efficiency.The main research results obtained are as follows:?1?The W/N co-doped TiO₂ nanobelts with significant photocatalytic activities were prepared by the hydrothermal method,introducing W and N sources in high temperature alkaline solution of NaOH.The modified TiO₂ nanobelts have a pure anatase crystal phase structure.W and N successfully enter the TiO₂ lattices and form the new states N 2p on top of O 2p states,reducing the bandgap to 2.1 eV.The overlap of O 2p and N 2p orbitals increases the lifetime of photogenerated carriers,which in turn leads to 91.6%degradation of rhodamine B?Rh.B?solution under visible light conditions.?2?W/N co-doped TiO₂ nanotubes were prepared by electrochemical anodic oxidation in organic electrolyte containing glycerol.The TiO₂ nanotubes with different structures,morphologies and properties were prepared via changing the oxidation time,doping concentration,annealing temperature and other factors to determine the optimal synthesis conditions of TiO₂ nanotubes.The photoelectrocatalytic properties of W/N co-doped TiO₂nanotubes and the synergistic effect of W and N on the photocatalytic activity of TiO₂nanotubes were investigated by electrochemical tests and visible light photocatalytic degradation experiments.?3?W/S codoped TiO₂ nanoparticles were synthesized by sol-gel method using sodium tungstate and thiourea as W and S sources,respectively.On this basis,zeolite loaded W/S co-doped TiO₂ nanoparticles with high photocatalytic activity were prepared by introducing ball-milled artificial zeolite powder as carrier.The effects of zeolite supports and W/S co-doping on the structure and morphology of TiO₂ nanoparticles were analyzed by XRD,SEM,EDX and Raman spectrum characterizations.The addition of zeolite to provide zeolite sites and combine with photogenerated electrons reduces the recombination of photogenerated electrons and holes and greatly enhances the visible light catalytic activity of TiO₂.