Investigation on optical and photoelectrochemical properties of self-assembled titania nanotube arrays prepared by anodization

• Main Authors: Lim, Ying Chin, Zainal, Zulkarnain, Hussein, Mohd Zobir, Tan, Wee Tee
• Format: Article
• Language: English
• Published: Malaysian Analytical Sciences Society 2016
• Online Access: http://psasir.upm.edu.my/id/eprint/27949/1/Investigation%20on%20optical%20and%20photoelectrochemical%20properties%20of%20self-assembled%20titania%20nanotube%20arrays%20prepared%20by%20anodization.pdf; http://psasir.upm.edu.my/id/eprint/27949/; http://www.ukm.my/mjas/new_mjas/

Well ordered and vertically oriented titania nanotubes (TNT) are of great scientific interest due to their high surface area, fewer interfacial grain boundaries and excellent charge transfer between interfaces; all are critical properties in photoelectrochemical and photocatalysis application. In this study, self-assembled TNT electrodes were synthesized by anodization of pure Ti in 0.5 wt.% NH4F solution (NH4F/H2O), in mixture of aqueous-organic solution (NH4F/H2O/EG) and in an organic solution (NH4F/EG). Choice of electrolytic medium has an influence on the crystalline structure, regularity, elemental composition and band gap of TNT. All the samples showed a red shift and stronger absorption in the wavelength between 500-700 nm ascribed to the surface colour and increase crystallinity upon calcination. TNT formed in NH4F/H2O solution has the highest direct band gap of 3.34 eV due to quantization effect. From Liner Sweep Photovoltammetry analysis, the lowest photocurrent was recorded for TNT anodized in NH4F/H2O and a twofold and fivefold increase on the magnitude of photocurrent was obtained for those formed in NH4F/H2O/EG and NH4F/EG solution, respectively. Hence, highest photoefficiency of 2.79 % was recorded for TNT formed in NH4F/EG probably due to the formation of longer length tube.