Facile Preparation and Photoinduced Superhydrophilicity of Highly Ordered Sodium-Free Titanate Nanotube Films by Electrophoretic Deposition

Minghua Zhou,Huogen Yu

doi:10.1155/2012/830321

Abstract

Highly ordered sodium-free titanate nanotube films were one-step prepared on F-doped SnO2-coated (FTO) glass via an electrophoretic deposition method by using sodium titanate nanotubes as the precursor. It was found that the self-assembled formation of highly ordered sodium titanate nanotube films was accompanied with the effective removal of sodium ions in the nanotubes during the electrophoretic deposition process, resulting in the final formation of protonated titanate nanotube film. With increasing calcination temperature, the amorphous TiO2phase is formed by a dehydration process of the protonated titanate nanotubes at 300°C and further transforms into anatase TiO2when the calcination temperature is higher than 400°C. Compared with the as-prepared titanate nanotube film, the calcined titanate nanotube film (300–600°C) exhibits attractive photoinduced superhydrophilicity under UV-light irradiation. In particular, 500°C-calcined films show the best photoinduced superhydrophilicity, probably due to synergetic effects of enhanced crystallization, surface roughness, and ordered structures of the films.

Highlights

Among various oxide semiconductors, titania appears promising and important for the use in environmental purification due to its strong oxidizing power, nontoxicity and long-term photostability [1,2,3,4,5,6,7,8,9,10]
When the sodium titanate nanotubes were deposited on the surface of FTO substrate by electrophoretic deposition (EPD) method, it is interesting to find that the as-prepared films show an ordered assembled structure of the nanotubes along their long-axis direction (Figure 1(b))
After the sodium titanate nanotube powder is deposited on the surface of FTO to form a film, it is found that no X-ray photoelectron spectroscopy (XPS) peaks corresponding to Na element are recorded in the asprepared film (Figure 3(b))

Summary

Introduction

Titania appears promising and important for the use in environmental purification due to its strong oxidizing power, nontoxicity and long-term photostability [1,2,3,4,5,6,7,8,9,10]. The further enhanced photoinduced hydrophilicity is necessary for practical uses To achieve this goal, great attentions should be focused on the textural design of the 2D TiO2 thin films. The EPD has a flexibility of depositing films on different shapes and sizes and can be extended to a large scale for commercial applications. Another advantage of this method is that it can be carried out at room temperature, thereby reducing the possibility of deterioration of the surrounding. It was demonstrated that the calcination of those titanate nanotube films above 300◦C converted into ordered TiO2 nanorod films with attractive photoinduced superhydrophilicity

Experimental

Results and Discussion

Conclusions