Research On The Preparation And Property Of Rare Earth Ions/TiO₂ Nanopowders

Since pure TiO₂ has many advantages such as unique chemical stability,innoxious,better photocatalysis activity TiO₂ has become the optimal material of photocatalyst,gas sensor and cell battery.But the low photocatalysis efficiency arise from the narrow spectral response range,the slow reaction speed and the compounding of photo-generated carrier seriously block the application of TiO₂.In this paper,the TiO₂ nanopowders doped with different rare earth ions(La³⁺,Ce³⁺,Y³⁺)were prepared by plasma spray.The powders were characterized by TEM,XRD,UV-Vis and XPS.The photocatalytic activity of samples at different doping concentration in photocatalytic degradation of methyl orange was discussed and the effect mechanics were analyzed.The results of TEM indicate that the powders prepared by plasma spray appear globular shape or approximate globular shape,and that the scope of particle distributing is between 10 and 50 nm.The results of XRD indicate that the TiO₂ powders are the mixture of anatase and rutile,doping rare earth ions can promote the transformation from anatase to rutile which restrains the growth of TiO₂ particle.Simultaneity, doping rare earth ions changes the lattice parameter and causes the distortion of lattice.The results of UV-Vis indicate that the band-edge of intrinsic absorption of ion doped TiO₂ appears red shift from that of pure TiO₂, and the degree of red shift enhances as the content of ion doping content increases.The results of XPS indicate that part of rare earth ions have entered the crystal lattice and replaced Ti⁴⁺,a great number of rare earth elements get together at the surface of TiO₂ in the form of La₂O₃,Y₂O₃ and CeO₂.Cerium has became Ce⁴⁺from Ce³⁺in the course of growth TiO₂.In photocatalysis experiments the photocatalysis activity of TiO₂ increases obviously doped with La³⁺ and Y³⁺under the UV-light.The degradation rate of methyl orange increases firstly and then decreases with an increase in the contents of doping La³⁺and Y³⁺in catalyst.The optimal doping content of La³⁺is 0.5%,the degradation rate of methyl orange has been increased from 78.3%to 97.5%in 90 mins.The optimal doping content of Y³⁺is 0.1%,the degradation rate of methyl orange is 98.4%in 90 mins.The degradation rate of methyl orange has not be increased greatly at visible light condition,the degradation rate of methyl orange of La³⁺is the best.