Facile fabrication of free-standing TiO2 nanotube membranes with both ends open via self-detaching anodization

We report the first direct synthesis of free-standing TiO2 nanotube membranes based on self-detaching electrochemical anodization. The films with high-quality surfaces and both-side-open tubes could be obtained by appropriate thermal treatment during the process. The membranes are optically transparent after subsequent annealing to induce crystallization. The possible mechanism of the multi-step electrochemical process is also presented. This self-detaching process developed here is easy and efficient without additional chemical dissolution or etching and is shown to open new prospects for the application of TiO2 nanotubes in various fields.