Visible-Light-Induced Self-Cleaning Property of Bi2Ti2O7‑TiO2 Composite Nanowire Arrays

• Published in: Langmuir 2015-06, Vol.31 (21), p.5962-5969
• Main Authors: Liu, Hang, Chen, Yajie, Tian, Guohui, Ren, Zhiyu, Tian, Chungui, Fu, Honggang
• Format: Article
• Language: English
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.5b00516

Bi2Ti2O7-TiO2 composite nanowire arrays were prepared via a two-step sequential solvothermal and subsequent calcination process. The morphology and structure of the Bi2Ti2O7-TiO2 composite nanowire array composite were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The UV–visible diffuse reflectance spectroscopy analysis indicated that the absorption spectrum of the Bi2Ti2O7-TiO2 composite nanowire array composite was extended to the visible-light region due to the existence of Bi2Ti2O7. The Bi2Ti2O7-TiO2 composite nanowire arrays exhibit superhydrophilicity with water contact angles of 0° after irradiation with visible light, and the superhydrophilic nature is retained for at least 15 days. This effect enables us to consider self-cleaning applications that do not require permanent UV exposure. Compared to pure Bi2Ti2O7 and TiO2, the vertically aligned Bi2Ti2O7-TiO2 composite nanowire arrays showed more significant visible-light self-cleaning performance due to the synergistic effect of superhydrophilicity and significant photocatalytic activity caused by effective electron–hole separation at the interfaces of the two semiconductors, which was confirmed by the electrochemical analysis and surface photovoltage technique.