Growth of rutile TiO_2 nanorods on anatase TiO_2 thin films on Si-based substrates

摘要

Synthesis of titania (TiO_2) nanorods on various substrates has recently attracted attention for energy and environmental applications. Herein, we report growth of nanostructured TiO_2 on Si(111) and glass borosilicate substrates by a two-step method. A thin film of anatase TiO_2 was first laid down by spin coating and annealing, followed by the growth of rutile TiO_2 nanorods with a hydrothermal method. To understand the role of the polycrystalline anatase TiO_2 seed layer, we selected a relatively high temperature for the hydrothermal reaction, e.g., 175 °C at which no rutile TiO_2 nanorods could grow without the precoated anatase TiO_2 layer. The morphology and microstructure of both the polycrystalline anatase and rutile nanorod layers were characterized by electron microscopy and x-ray powder diffraction. Such a two-step fabrication method makes it possible to grow TiO_2 nanorods on almost any substrate.