Efficient vapor-liquid-solid synthesis of copper doped zinc oxide (Cu:ZnO) nanonails with highly homogeneous dopant distribution

Abstract

Copper doped zinc oxide (Cu:ZnO) nanonails with uniformly distributed Cu ions through the nail structure were synthesized via a vapor-liquid-solid technique using seed Cu:ZnO nanoparticles. The seed nanoparticles were prepared with a simple precipitation method. The structure and morphology of nanonails and the distribution of Cu ions were investigated using X-ray diffraction, electron energy loss spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elemental mapping analysis. The defect states in the Cu:ZnO nanonails were characterized by room temperature photoluminescence (PL) spectra. The obtained Cu:ZnO nanonails have single phase wurtzite structure of ZnO and incorporated copper ions are in the Cu2+ oxidation state. SEM and TEM micrographs revealed that nanostructures with well-defined nail morphology composed of a hexagonal cap (~350 nm in diameter) and a prismatic shaft (~550 nm in diameter) connected with cylindrical neck (~250 nm in diameter). Both SEM and TEM elemental mapping analysis proved that the usage of Cu:ZnO seed nanoparticles resulted in highly homogeneous distribution of Cu ions into ZnO nanonails. High crystallinity of the Cu:ZnO nanonails was revealed with PL spectra composed of predominant second order diffraction peak and near band edge of UV emission peak and also weak defect related deep level green and violent emission peaks.