Effect of Li(I) and TiO2 on the upconversion luminance of Pr:Y2SiO5 and its photodegradation on nitrobenzene wastewater

Based on the substrate of pr:y2sio5 upconversion nanomaterials,lithium ion li(i) doped pr:y2sio5 and tio2 nanofilm coated li,pr:y2sio5 composites were prepared by using a sol-gel method. x-ray diffractometer,sem,and fluorescence spectrometer have been employed to test the crystal structure,microimages,and upconversion luminescence performances. the doping of li(i) affects highly the crystal transition of pr:y2sio5 and x2-y2sio5 phase was well formed by doping 8% li(i). furthermore,the doping of li(i) also brings high luminance intensity of pr:y2sio5 and contributes to a maximum intensity of 9.76 × 106 cps doped 8%. too much of li(i) doping would result in big crystal size and fluorescence quenching of pr:y2sio5 material. however,the coating of tio2 nanofilm is not helping in increasing the upconversion fluorescence of li,pr:y2sio5 but is promoting the full use of the fluorescence. the luminescence intensities of tio2/li,pr:y2sio5 composites are getting down sharply with the coating amount since the luminescence emitted by li,pr:y2sio5 is quickly adsorbed in situ by the tio2 coating film. with the optimum coating concentration of 1%,the tio2/li,pr:y2sio5 composite shows excellent photodegradation performances on nitrobenzene wastewater,though it shows a low luminescence intensity. for 5 mg/l nitrobenzene wastewater,the composite presents a photodegradation rate of 97.08% in 4 hours. © 2015 yi yang et al.