Spontaneous phase and morphology transformations of anodized titania nanotubes induced by water at room temperature.

We report a spontaneous phase transformation of titania nanotubes induced by water at room temperature, which enables the as-anodized amorphous nanotubes to be crystallized into anatase mesoporous nanowires without any other post-treatments. These mesoporous TiO(2) nanomaterials have a markedly improved surface area, about 5.5 times than that of the as-anodized TiO(2) nanotubes, resulting in a pronounced enhanced photocatalytic activity. The present approach not only allows a flexible control over the morphology of TiO(2) nanostructures but can fundamentally eliminate the need for high temperature operations for crystallizing amorphous TiO(2).