Preparation And Photocatalytic Properties Of TiO_2-xN_x/Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ Composite Materials

Photocatalytic degrading pollution using semiconductor materials is a kind ofenergy efficient and green environmental technology, which is paid close attention dueto no second pollution and low energy consumption et al. It possess the advantage ofmild reaction condition, degrading organic pollution to inorganic little molecules suchas carbon dioxide and water and high degradation efficient. At present, It has becomethe hot spot that searching and designing the photocatalytic materials with high catalyticactivity.In this study, a kind of new style photocatalytic composite materialsTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+was fabricated by Sol-gel coating process that thesurface of long afterglow phosphor (Sr2MgSi2O7:Eu2+,Dy3+) was coated withnitrogen-doped TiO2. Morphology, structure and photocatalytic properties ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+under the different treatments were investigated usingX-ray diffraction (XRD), scanning electron microscope (SEM), opticaldiffuse-reflection spectra (DRS) and photoluminescence spectrum (PL).It was studied that the effect of the calcination temperature, calcination time,coating rate, coating time and acidity on the structure and morphology ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materials. The results show that the crystalstructure of Sr2MgSi2O7:Eu2+,Dy3+is not almost affected by the coating of TiO2-xNx.The main phase of TiO2-xNxis the anatase structure under calcination temperature400oC for1h. The phase transition from anatase to rutile is restrained by the dopingnitrogen. The effect of coating of TiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materialsis the most best and luminescence properties of that are also the highest under acidity0.03mol/L, calcination temperature400oC for1h, coating rate4:1for1.5h. But thestrength of emission spectroscopy of TiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+compositematerials is lower than that of Sr2MgSi2O7:Eu2+,Dy3+.It was studied that the effect of the different fabricated conditions ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materials on the degradation efficiency of methyl orange. The results show that the photodegradation of20mg/L methyl orangesolution is94.5%under2h illumination in the suspending system ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+, which was fabricated under calcined at400oC for1h,coated rate4:1for1.5h, which indicates the catalytic activity ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materials is high under above-mentionedconditions. It was certified that the hole plays a leading role using different captureagents in the process that methyl orange was photocatalytic degraded byTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materials. we recognize thatTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+produce Eu+and hole under the illumination condition.The transfer of the hole in the energy band of Sr2MgSi2O7:Eu2+,Dy3+and TiO2-xNxisthe main reason of the increase of the photocatalytic efficiency ofTiO2-xNx/Sr2MgSi2O7:Eu2+,Dy3+composite materials.