| Water-splitting Performance of TiO2 Nanotube Arrays Annealed in NH3 Ambient |
| Se-Im Kim, Sung-Jin Kim, Bee-Lyong Yang |
| Department of Information and Nano-Materials Engineering, Kumoh National Institute of Technology |
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| ABSTRACT |
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Increase of surface area and decrease of band gap in $TiO_2$ semiconductors are significant to improve the efficiency of water splitting by photoelectrolysis. In this study $TiO_2$ nanotube arrays with ~7 um length and ~100 nm diameter were fabricated by an anodizing technique of titanium foils using DMSO (dimethyl sulfoxide)-based electrolytes. Then to control the band gap of the $TiO_2$ arrays, they were annealed at $550^{circ}C$ for up to 180 min in $NH_3$ gas ambient. The samples annealed in $NH_3$ gas for 30 min and 60 min showed superior photo-conversion efficiency for water splitting under white and visible light. A $TiO_2$ nanotube annealed in $NH_3$ gas ambient for a period longer than 120 min showed 1 order higher leakage current. It is believed that the decrease of band gap and increase of conductivity in $TiO_2$ nanotube arrays due to $NH_3$ gas treatments result in the superior water-splitting performance. |
| Key words:
$TiO_2$, Nanotube, Nitrogen doping, Photocatalysis |
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