Enhancing persistent luminescence and photocatalytic properties in Ti as a trap center in ZnGa2O4

ZnGa2O4 and ZnGa2O4: Ti phosphors were synthesized by the solid state method, and their persistent luminescence and photocatalytic properties were investigated in detail. The results of this study showed that Ti4+ doping improved the persistent luminescence properties. Thermoluminescence measurements demonstrated that the trap concentration considerably increased upon incorporation of Ti (4+) ions into the ZnGa2O4 lattice. The traps generated by Ti doping were responsible for improvement in persistent luminescence. Furthermore, photocatalytic activity tests showed that the Ti-doped ZnGa2O4 phosphor exhibited much higher photocatalytic activity than the ZnGa2O4 host. UV-Vis diffuse reflectance spectra demonstrated that Ti-doped ZnGa2O4 shown a higher UV absorption efficiency. A comparison between the density of states of ZnGa2O4: Ti and ZnGa2O4 revealed that the bottom of the conduction band was modified by Ti doping. Hence, it could be concluded that Ti doping enhanced light harvest capability to generate more electron-hole pairs, and acted as a trap center by decreasing the recombination of photogenerated electrons and holes, resulting in the enhancement of both persistent luminescence and photocatalytic activity.