Photocatalytic Oxidation of Methyl Orange over Boron-doped TiO2 Nanotube Arrays
Date Issued
2010
Date
2010
Author(s)
Shang, Wei-Ting
Abstract
The objective of this study was to modify TiO2 nanotube arrays with boron via two doping methods including chemical vapor deposition and electrodeposition. With various characterizations including Field-Emission Scanning Electron Microscope (FE-SEM), Raman Spectrophotometer, X-Ray Diffractometer (XRD), UV-Visible Spectrophotometer (UV-Vis) and Fourier Transform Infrared Spectrophotometer (FT-IR), the effects of aspect ratios of TiO2 nanotube arrays on the doping performance were investigated. The photoactivity of B-doped TiO2 nanotube arrays was also examined in terms of the oxidation efficiency of methyl orange (MO).
The XRD patterns of TiO2 nanotube arrays calcined at 500 ℃ showed that the intensity of anatase peak increased with increasing the aspect ratio. After boron doping, the intensity of anatase peaks decrease. The UV-Vis DRS spectra indicated that the absorption intensity of the B-doped TiO2 nanotube arrays was enhanced both in the UV and visible regions. In addition, all the B-doped TiO2 nanotube arrays exhibit red shifts.
The results indicated that the photoactivity of TiO2 nanotube arrays is significantly dependent on the aspect ratio. An increase in the aspect ratio of TiO2 nanotube arrays leads to an improved efficiency of MO oxidation. Furthermore, the photoactivity of TiO2 nanotube arrays was enhanced after B doping via either chemical vapor deposition or electrodeposition. The optimum boron doping concentration prepared by electrodeposition was lower than that by chemical vapor deposition. Meanwhile, the enhancement of photocatalytic performance of B-modified TiO2 nanotube arrays is apparent when the aspect ratio is lower. This result is probably owing to the fact that the larger the aspect ratio, the less TiO2 nanotube arrays can be modified. Based on the FT-IR spectra, the intensity of MO absorption bands over B-modified TiO2 nanotube arrays vanished after 0.5 h UV illumination whereas the MO signal over unamended TiO2 nanotube arrays remained obvious after 2 h UV illumination.
Subjects
Anodic oxidation
Boron doping
Chemical vapor deposition
Electrodeposition
Photocatalysis
TiO2 nanotube arrays
Type
thesis
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