Photoluminescence properties of cerium-doped zinc oxide nanotubes prepared using electrodeposition technique

Well-ordered ZnO and Ce-doped ZnO (Ce-ZnO) nanotubes arrays with external diameter of 60 nm are obtained by oxidizing the Zn and Ce-Zn nanotube arrays electrodeposited into self-made anodic aluminum oxide template under different deposition potentials. The ratio of Ce to Zn in Ce-ZnO nanotubes can be modulated by deposition potentials. Like ZnO nanotubes, all Ce-ZnO nanotubes display polycrystalline hexagonal wurtzite structure without a distinctly preferential orientation. Nevertheless, due to smaller Zn ions being partly replaced by larger Ce ions, lattice parameters of Ce-ZnO nanotubes slightly increase in comparison with ZnO nanotubes. The only present ultraviolet (UV) emission peak as well as absent defect emission peak in all samples including ZnO nanotubes, indicates that all nanotubes synthesized by the electrochemical deposition possess good crystallinity. Compared with ZnO nanotubes, Ce-ZnO nanotubes fabricated under deposition potential of - 1.35 and - 1.4 V exhibit stronger UV emission. Especially in the case of - 1.35 V, Ce-ZnO nanotubes with the Ce:Zn ratio of 1:7 display twice the UV emission intensity of ZnO nanotubes, which shows doping an appropriate amount of Ce into ZnO nanotubes can sharply increase UV emission. The reason for the enhancement of UV emission is that CeO2 in Ce-ZnO nanotubes also has the stronger UV emission. These hollow Ce-ZnO nanotubes could have potential application in UV light-emitting diodes, photocatalysis, gas sensor, drug delivery, or other nanodevices.