Formation of Core/Shell-Type ZnO/CeO2 Nanorods and CeO2 Nanotube Arrays by Aqueous Synthesis and Wet-Etching

Aqueous synthesis and wet-etching process for fabricating core/shell-type ZnO/CeO2 nanorods and CeO2 nanotube arrays without any chemical modification or assisted surfactant are reported. Ce ions are adsorbed on ZnO to form core/shell-type ZnO/CeO2 nanorods and polycrystalline CeO2 nanotubes are fabricated by wet-etching the ZnO cores with a dilute hydrochloric acid solution. The as-synthesized ZnO/CeO2 nanorods reveal that the ZnO cores are coated with CeO2 shells to form a plastered layer. The obtained CeO2 nanotubes show a perfect hexagonal structure and large cavities. The possible formation mechanism for the core/shell-type ZnO/CeO2 nanorods and CeO2 nanotube arrays is discussed.