Thermal Reduction Route to the Fabrication of Coaxial Zn/ZnO Nanocables and ZnO Nanotubes

Coaxial Zn/ZnO nanocables and ZnO nanotubes have been fabricated via a thermal reduction route using ZnS powder as the source material. The samples were characterized using X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. The as-synthesized Zn/ZnO nanocables consisted of a metallic core (Zn) ≈50 nm in diameter and a semiconductor outer shell (ZnO) ≈5 nm in thickness and several micrometers in length. A good epitaxial relationship between the Zn core and ZnO shell was observed, and misfit dislocations were observed at the Zn/ZnO interface, which accommodated the relatively large lattice mismatch. The outer diameter and wall thickness of the ZnO nanotubes are ≈60 and ≈10 nm, respectively. The possible formation mechanisms for the Zn/ZnO nanocables and ZnO nanotubes are discussed.