Preparation And Catalytic Performance Of Rare Earth Doped Nano-TiO₂

Semiconductor photocatalyst represented by titanium dioxide is widely used in many fields such as green,energy saving and environmental protection.TiO₂ shows the characteristics of good chemical stability,non-pollution to the environment and low preparation cost,but it's application is limited to a certain extent due to wider band gap and wider spectral absorption.By means of rare earth element doping,metal loading,and semiconductor compounding,it can be realized that broaden the absorption range of the spectrum effectively,enhance the carrier separation efficiency,and then improve the catalytic performance of TiO₂.That methods have become the biggest hot spot for studying TiO₂modification.According to the limitations,TiO₂ is modified from three aspects in current paper,thus enhancing the catalytic performance of TiO₂.First,one-step hydrothermal method was used to prepare La-doped nano-TiO₂photocatalysts.Titanium sulphate and ruthenium oxide were used as starting materials and reacted for 12 hours at a hydrothermal temperature of 180°C to prepare titania microspheres.Rhodamine B with a concentration of 10 mg/L was degraded to measure the photocatalytic activity of the catalyst.The samples were characterized by SEM,EDS,XRD and UV-Vis DRS.The experimental results show that the La-doped titania microspheres can be prepared by one-step hydrothermal method with particle size of 73nm.When the molar ratio of titanium oxysulfate to urea is 1:2,the catalytic activity was best and the degradation rate of Rhodamine B achieve 87%.When 0.5%La was blended,the catalytic performance is better,and the degradation rate of 10mg/L Rhodamine B is 95%at 70min.The photocatalytic activity is increased by 8%by doping with rare earth La.Secondly,with titanium titanyl sulfate as the source of titanium and lanthanum nitrate as raw material,Nd-doped nano-TiO₂ was prepared by one-step hydrothermal method.The samples were characterized by XRD,SEM,TEM,and UV-Vis DRS.The experimental results show that the as-synthesized samples are all micro-spherical TiO₂,with uniform dispersion and little agglomeration.The doping of rare earth Nd did not change the crystal shape of TiO₂.It was still anatase after doping and had a particle size of 80 nm.The dopped rare earth Nd could make the band gap of TiO₂ more narrow,further widen the photoresponse range of TiO₂,and enhance the photocatalytic performance effectively.The optimal preparation conditions of TiO₂ are as follows:initial concentration of titanium was 0.05 mol/L,molar ratio of titanium to urea was 1:2,pH of reaction solution was 2,and reaction temperature was180°C.The prepared Nd-TiO₂ exhibits the best catalytic activity when the Nd doping content is 0.08%,and the degradation rate of the Rhodamine B can reach 98%.The photocatalytic activity can be increased by 12%with doping rare earth Nd.Thirdly,carbon-doped mesoporous TiO₂ hollow microspheres?C-TiO₂?were obtained through hydrothermal reaction and high-temperature calcination using glucose as a template and carbon source.The hydrothermal temperature was 180°C for 12 hours and C-TiO₂ was a carrier,AgNO₃ and Na H₂PO₄ loaded into the TiO₂ mesoporous channels,to improve the photocatalytic activity of TiO₂ by in-situ generation of Ag₃PO₄ in the photocatalytic process.The samples were characterized by XRD,SEM,TEM,and UV-Vis DRS.Rhodamine B was used as a simulated contaminant to characterize the catalytic performance of the sample under UV and visible light.The experimental results show that the degradation rate of C-TiO₂ reach95.3%at 35 min under UV irradiation.Ag sensitized TiO₂ with 5.6%silver loading show the best photocatalytic activity,the degradation rate is 98.6%under ultraviolet light for 20minutes,and the degradation rate reach 99.3%for 40 min under visible light.