Synthesis and Characterization of Self-Organized Oxide Nanotube Arrays via a Facile Electrochemical Anodization

• Published in: Journal of physical chemistry. C 2008-12, Vol.112 (50), p.19852-19859
• Main Authors: Liu, Shikai, Fu, Wuyou, Yang, Haibin, Li, Minghui, Sun, Peng, Luo, Baomin, Yu, Qingjiang, Wei, Ronghui, Yuan, Mingxia, Zhang, Yanyan, Ma, Dong, Li, Yixing, Zou, Guangtian
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp803516d

Self-organized oxide nanotube arrays have been prepared by a facile two-electrode electrochemical anodization on Ti-2Al-1.5Mn alloy in a 0.5 wt % NH4F aqueous electrolyte. The surface morphology, structure, elemental analysis, and optical and photoelectrochemical behaviors of the nanotubular films are considered. The morphology greatly depends on the applied voltage and anodization time. The as-formed nanotubes under the optimized condition, at 20 V for 3 h, are highly ordered with ∼500 nm in length and the average tube diameter is about 90 nm. The possible “oxide growth and dissolution” mechanism is also discussed. By annealing the initially amorphous films at different temperatures, the importance of the crystalline nature is confirmed. A continuously remarkable red-shift of the absorption edge has been observed with increasing annealing temperature, which is related to the increasing crystallization and the possible new energy bands formed in the TiO2 band gap. The photoelectrochemical properties are investigated and the highest photocurrent of 3.11 mA/cm2 is obtained under AM1.5 100 mW/cm2 illumination at 0.65 V (vs Ag/AgCl). Significantly, a considerable and sustained water splitting behavior has also been observed, and the present convenient synthesis technique can also be extended to other binary or ternary oxide compositions for various applications.