Two-step growth behavior of TiO₂nanorod array grown by hydrothermal synthesis
Yen-Wen Lu1, Wen-Jen Lee1*
1Department of Advanced Thin Films Process, National Pingtung University, Pingtung, Taiwan
* presenting author:李文仁,
Titanium dioxide (TiO2) is an n-type semiconductor with a bandgap energy of about 3.0 - 3.2 eV. Nanostructural TiO2 materials such as TiO2 nanospheres, nanotubes, nanowires, and nanorods have been widely applied in photocatalysts, lithium-ion batteries, gas sensors, dye-sensitized solar cells, and ultraviolet photodector due to its unique and excellent properties in optics, electronics, and photochemistry. The hydrothermal synthesis is a low-cost and simple technology for fabrication of several nanomaterials. In this study, the TiO2 nanorod arrays (TNAs) were grown on FTO-glass substrates by hydrothermal synthesis. The relations of reaction temperature, reaction time, and the growth behavior of TNAs have been carefully discussed and an interesting phenomenon is found. There are two kinds of growth behaviors observed in the process of TNAs grown by hydrothermal synthesis. At initial stage, the TiO2 nanorods are horizontally grown on the substrate. After a period of time, the growth of TiO2 nanorods is transited from horizontal to vertical growth. The growth behavior of TNAs is dominated by the reaction time and temperature of hydrothermal synthesis of TNAs. The transition time of horizontal-to-vertical growth is decreased with increasing reaction temperature of hydrothermal synthesis.

Keywords: Titanium dioxide, nanorods, hydrothermal synthesis, nanomaterial