One-step preparation of MgO hollow spheres and hexagonal cylinders via Zn template

Polycrystalline hollow spheres and single crystalline hexagonal cylinders of MgO have been fabricated by chemical vapor deposition using ZnO and Mg as the starting materials. The Zn produced during the chemical reaction serves as template material, and vaporization of which leads to the formation of the hollow structures. The presence of trace amount of Si in the source material is identified to be critical for the existence of the stable MgO hollow structures, which otherwise would be damaged during the Zn template removal process. The same principle can be readily adopted in many other material systems and result a variety of hollow structures for catalyst, sensor and medical applications.