Preparation And Modification Of Nanosized TiO₂ By Microemulsion Method And Study On Its Photocatalytic Activity Under Visible Light

Inthispaper,thestabilityofmicroemulsionsystem cyclohexane/Tween80/n-butanol/water were investigated by using maximum water solubilization amount as target,in which orthogonal experiment was designed to obtain the optimal ratio of microemulsion components.Nano-TiO₂ was successfully prepared with high monodispersity in this microemulsion system using concentrated sulfuric acid as inhibitors,tetrabutyl titanate as titanium source.The products were all spherical shape with high crystalinity of anatase phase and the size distribution was uniform,the average particle size was about 14 nm.In the cyclohexane/Tween80/n-butanol/water microemulsion system,TiO₂ was modified by Ag?Fe?Co?Yb?Ce and N doping respectively.The impact of metal or non-metal element doping into TiO₂ on the crystal phase and performance of photocatalytic activity was investigated.The results showed that Ag-doping into TiO₂would not affect the crystal structure of anatase TiO₂,while TiO₂ doped Fe was pure anatase when the amount of Fe-TiO₂ was greater than 0.1wt%.Co?Yb?Ce and N-doped nano-TiO₂ products were all mixed crystals of monoclinic TiO₂?often referred to as?-TiO₂?and the cubic anatase TiO₂.When the calcination temperature was between 700?and 800?,they were all converted to the pure anatase,which demonstrated that the doping of Co?Yb?Ce?N effectively suppressed TiO₂transformation from anatase to rutile phase transition and improved the crystal transformation temperature.The photocatalytic activity of single element doping nano-TiO₂ was evaluated and the result showed that TiO₂ doped Ce or N had the best performance of degradation on new carmine and the efficiency could reach above80%.N-Ce co-doping into TiO₂ was conducted in the same microemulsion system.The products were characterized by XRD and TEM,the results showed that the shape of N-Ce co-doped TiO₂ was spherical and the average particle size was about 20 nm with high crystalinity of anatase phase.PL and XPS analysis indicated that Ce element exists in the form of Ce⁴⁺,N atoms were successfully doped into the crystal lattice of TiO₂ substituting oxygen atoms to form Ti-O-N or O-Ti-N bond.N and Ce atoms could be served as trapping centers of electrons and holes to inhibit recombination of photo-generated electrons and holes.The photocatalytic activity of N-Ce co-doping nano-TiO₂ was evaluated under visible light.Compared with single element doping TiO₂,pure TiO₂ and P25,N-Ce-TiO₂ showed the best degradation efficiency of the new carmine under the visible light region,which reached 95%within 90 min.