Temperature-dependent differences in wettability and photocatalysis of TiO2 nanotube arrays thin films

• Published in: Applied surface science 2015-11, Vol.356, p.546-552
• Main Authors: Zhang, Miao, Yao, Guang, Cheng, Yunlang, Xu, Yanyan, Yang, Lei, Lv, Jianguo, Shi, Shiwei, Jiang, Xishun, He, Gang, Wang, Peihong, Song, Xueping, Sun, Zhaoqi
• Format: Article
• Language: English
• Subjects: Annealing; Annealing temperature; Anodization; Anodizing; Arrays; Morphology; Nanostructure; Photocatalysis; Thin films; TiO2-nanotube; Titanium; Titanium dioxide; Wettability
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.08.117

•The anodization conditions were studied carefully and the uniform surface morphology was obtained under certain conditions.•Unique morphology composed by nanowire@nanotube can be seen after calcining treatment.•The water contact angle before and after UV light illumination were test repetitively, and the error of water contact angle were measured. Tiny change of contact angle was observed when samples were annealed at 600°C.•The sample annealed at 600°C exhibits the highest photocatalytical activity among the samples. TiO2 nanotubes arrays (TiO2-NTAs) layers were successfully formed by electrochemical anodization on a titanium (Ti) surface in fluorine-containing electrolytes under different processing voltages and annealing temperatures. The formed TiO2-NTAs layers annealed at different temperatures were compared in terms of their morphologies, structures and band gaps. Their wetting abilities, photo-induced hydrophilicities and photocatalytic performances were also evaluated. It was found the sample anodized at 40V for 2h have the most uniform surface morphology. The TiO2-NTAs structures annealed at 600°C for 2h in air show multiphase crystallinity and have the narrowest band gap (2.89eV). These structures have noticeable nanowires on the top of the nanotubes. Their photocatalytic activity, tested by degradation of aqueous methylene orange solutions under UV light illumination for 2h, is the highest among all samples (degradation efficiency was 89.05%). Specimens annealed at 200, 400 and 800°C show light-induced hydrophilicity. However, small contact angle change was observed when samples were annealed at 600°C.