Preparation, Characterization, and Photocatalytic Properties of Self-Standing Pure and Cu-Doped TiO Nanobelt Membranes.

A traditional hydrothermal method was modified to synthesize ultra-long sodium titanate nanobelts by simultaneously stirring the solution. The ultra-long sodium titanate nanobelts were converted to hydrogen titanate nanobelts through an ion exchanging way. A method was then used to prepare self-standing flexible large-area membranes; they were then subject to post-annealing at different temperatures to obtain a self-standing TiO nanobelt membrane with a slight decrease in flexibility. Cu-doped TiO membranes were prepared by ion exchanging and post-annealing in the same manner. X-ray diffractions, scanning electron microscopy, field-emission scanning electron microscopy, field-emission transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and UV-vis spectroscopy were used to characterize the samples. Photodegradation of methylene blue (MB) water solutions was used to evaluate the photocatalytic activity. It was seen that the pure sample presented obvious visible-light responding photocatalytic activity, possibly due to the self-sensitization of the MB molecule. The UV-induced photocatalytic activity is higher because of the photoinduced holes and electrons. It was suggested that the Cu dopant induced intra-gap states from electron traps and recombination centers, resulting in the decrease in both of the visible and UV induced photocatalysis.