A facile method for the synthesis of tapered ZnO:Cu nanorod arrays and its secondary growth

A facile thermal diffusion method has been employed to synthesize tapered ZnO:Cu nanorod arrays. The plain hexagonal ZnO nanorods gradually turned into round cylinder and then tapered nanorods during thermal treatment. The shape evolution was explained by the terrace–ledge–kink model. Moreover, a small amount of copper has been incorporated into the nanorods during high temperature thermal treatment. Both X-ray photoelectron spectrum and photoluminescence results indicated that a number of oxygen vacancies exist in copper diffused samples. In addition, a catalyst free secondary growth was achieved on the tapered ZnO:Cu nanorod arrays. High resolution transmission electron microscope result showed that the tapered nanorods after secondary growth remained as a single crystal and the thinner section was epitaxially grown on the tip.

► A novel morphology evolution of ZnO nanorod arrays induced by annealing.
► The morphology evolution mechanism has been discussed systematically.
► It is a new method for the preparation of tapered ZnO:Cu nanorod arrays.
► Secondary growth has been done on the tapered nanorods.