Development Of Carbon And Potassium-Incorporated Titanium Dioxide Nanotube Arrays For Solar Energy Harvesting Applications

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Date
2013-05
Authors
Krengvirat, Warapong
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Publisher
Universiti Sains Malaysia
Abstract
TiO2 nanotube arrays have attracted great interest as the most promising candidate for solar energy harvesting applications. However, poor visible-light absorption and high recombination of charge carriers still remain as challenging issues for their practical applications. Hence, the objective of this work was to develop carbon and potassium-incorporated TiO2 nanotube arrays for solar energy harvesting applications, including photodecolorization, photoelectrochemical cell (PEC) and dye-sensitized solar cells (DSSC). Visible-light responsive TiO2 nanotube arrays were rapidly grown with a rate of ~289 nm min-1 by anodic oxidation in ethylene glycol (EG) containing 0.5 wt% ammonium fluoride (NH4F) and 1 wt% H2O. The presence of adsorbed-carbonate species and interstitial carbon in TiO2 nanotubes originated from the pyrogenation of EG resulted in the generation of localized state, and thus enabled the visible-light absorption. Anatase TiO2 nanotube arrays with high surface area (110.9 m2 g-1) were obtained by facile immersion of as-anodized nanotube arrays in hot water at ~90C. Such hot water-treated nanotube arrays exhibited efficient visible-light photodegradation of methylene blue with the decomposition rate of ~11 % h-1. This value is relatively higher than heat-treated arrays (~9 % h-1) and P25 powder (~2 % h-1). However, heat treatment at 400C for 4 h was found as essential approach to obtain better crystallinity for high PEC and DSSC properties.
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Keywords
Carbon And Potassium-Incorporated Titanium Dioxide Nanotube Arrays , Solar Energy Harvesting Applications
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