Study On TiO₂ Nanotube Synthesized Via Hydrothermal Method And Photocatalytic Activity

TiO2 nanotubes have attracted much interest due to their high surface-to-volume ratios and sizedependent properties, compared to any other form of titania, and the potential applications in the areas such as photocatalysis, sensing and solar cell.In this paper, the TiO2 nanotube were prepared by hydrothermal method .We had concentrated on the factors affected on the growth of titania nanotube, such as the hydrothermal duration, the different temperatures for hydrothermal reactions and different organic solvent in post-treatment. The experiments showed that the nanotubes of titanium oxide would grow longer and the diameter of TiO2 nanotube would grow wider with the hydrothermal duration. But the longth and diameter of TiO2 nanotube would not increase after 48h. As the temperatures for hydrothermal reactions grow, the amount of TiO2 nanotube became bigger, and the structure and morphology of TiO2 nanotube were better. The optimum TiO2 nanotube was obtained at 150℃.The reaseach on different organic solvent in post-treatment reveal that the optimum aggegation was obtained after washed by ethanol. It is helpful to the recovery in the area of photocatalysts for practical use.TiO2 nanotube was annealed at different tempature, the XRD experiments showed that the crystal type of TiO2 nanotube arrays would be transformed from anatase to rutile as the annealing temperature increased. The annealing tempature that rutile appeared in air was lower than in nitrogen. EDX patterns and XPS spectra proved oxygen vacancies were available when TiO2 nanotube annealed in nitrogen.In this paper, degrading methylene blue under different conditions and the factors on the photocatalytic activity of TiO2 nanotube were discussed. The result showed that the photocatalytic activity of titania nanotube annealed in nitrogen was better than in air. That is because the photocatalytic efficiency can increase via oxygen vacancies.Recycling studies of the reactions of photocatalytic activity with aggregation of TiO2 nanotubes showed that aggregation structure was easily recycled, maintaining 98.46% of dye degradation after 10 catalytic cycles, but the activity of P25 decreased dramatically to 13.39%. This fact can be explained that TiO2 nanotubes suspension is instability in aqueous solution due to the structure of aggregation like clew. Thus the aggregation of TiO2 nanotubes must be promising in the area of photocatalyst in practice use.