Enhanced photocatalytic activity of nanotube-like titania by sulfuric acid treatment

Article type: Research Article

Authors: YANG, Shao-gui | QUAN, Xie | LI, Xin-yong | FANG, Ning | ZHANG, Ning | ZHAO, Hui-min

Affiliations: School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China

Note: [] Corresponding author. E-mail: [email protected]

Abstract: The TiO_2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150°C. The as-prepared nanotubes were then treated with H_2SO_4 solutions. The TiO_2 nanotube has a crystalline structure with open-ended and multiwall morphologies. The TiO_2 nanotubes before and after surface acid treatment were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-VIS dispersive energy spectrophotometry (DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II in aqueous solutions. It was found that the order of photocatalytic activity was as follows: TiO_2 nanotubes treated with 1.0 mol/L H_2SO_4 solution (TiO_{2 (1.0M H_2SO_4)} nanotubes) > TiO_2 nanotubes treated with 0.2 mol/L H_2SO_4<FORMULA> solution (TiO<FORMULA>_{2(0.2MH_2SO_4)} nanotubes) > TiO_2 nanotubes > TiO_2 powder. This was attributed to the fact that TiO_2 nanotubes treated with H_2SO_4 was composed of smaller particles and had higher specific surface areas. Furthermore, the smaller TiO_2 particles were beneficial to the transfer and separation of photo-generated electrons and holes in the inner of and on the surface of TiO_2 particles and reduced the recombination of photo-generated electrons and holes. Acid treatment was particularly effective for TiO_2 nanotubes, this increase in activity was correlated with the concentration of H_2O_4 solution.

Keywords: titania nanotube, photocatalytic activity, acid orange II, H[TeX:] _2SO[TeX:] _4 solutions

Journal: Journal of Environmental Sciences, vol. 17, no. 2, pp. 290-293, 2005