Preparation And Photocatalytic Properties Of Low-dimensional TiO₂ Materials By Electrostatic Jet Method

Currently TiO₂ was the most promising photocatalytic material.TiO₂ nanoparticles or microspheres had large specific surface areas.Their photocatalytic effects were excellent,but it was difficult to recycle.TiO₂ fibers prepared by electrospinning could solve this problem,while the photocatalytic properties of TiO₂ fibers couldn't reach the actual requirements.Preparation of TiO₂ material which had both photocatalytic properties and recycling requirements was the focus of current research in this field.In the paper,electrostatic jet method?electrospraying,electrospinning?was applied to prepare the mixed crystal low-dimensional TiO₂ materials,which having fiber-microsphere composite structures were composed of rutile TiO₂ and anatase TiO₂ by a certain percentage.Because of microspheres distributing on fibers,they not only had large surface area,but also was easily to recycle.The process for the mixed crystal low-dimensional TiO₂ materials was optimized.The effects of viscosity?surface tension and conductivity of the precursor solutions on the morphologies of samples were investigated,and the mechanisms of action were elucidated.The constituents?structures and photocatalytic properties of samples were characterized.The following results showed that:?1?Composite microspheres were fabricated by electrostatic jet method using the TiO₂precursor solutions with 3⁹wt%PVAc concentration.3wt%was entirely spherical and 5⁹wt%were like erythrocytes structures.Meanwhile 9wt%began to produce fibers.Anatase TiO₂microspheres were obtained from composite microspheres calcined at 550?for 2h.In the light conditions,the degradation effect of TiO₂ microspheres from the precursor solution with 3wt%PVAc concentration on 10mg/L methylene blue solution in 40 min was best.The optimum concentration of TiO₂ microspheres was 2g/L,but the optimum calcination temperature was600?.?2?Through electrospinning technique,composite fibers whose surfaces were roughness were fabricated by the TiO₂ precursor solutions containing rutile nanoparticles.Mixed crystal TiO₂ fibers were prepared from composite fibers calcined at 550?for 2h,which were composed of rutile TiO₂ and anatase TiO₂ by a certain percentage.Photocatalytic results showed that,the photocatalytic propertie of 8:2 rutile/anatase mixed crystal TiO₂ fibers was excellent,compare with anatase TiO₂ fibers,whose degradation rate increased 6.36%.?3?The mixed crystal low-dimensional TiO₂ materials having fiber-microsphere composite structures were prepared by coaxial electrospinning technique.When core and shell advance rates were both 0.32ml/h,calcination temperature was 550?,the degradation rate of low-dimensional TiO₂ materials was 91.56%,better than the mixed crystal TiO₂ fibers.