Fluoride-free self-templated synthesis of hollow TiO₂ nanostructures for hydrogen evolution

Hollow TiO₂ nanostructures have been fabricated by a facile self-templated hydrothermal synthesis without the assistance of any fluoride compound. The hollow nanostructures with diameters of approximately 2 μm are composed of mesoporous shell walls of 200 nm in thickness. On the basis of the investigation result, it was found that the inside-out Ostwald ripening was responsible for the hollowing process in which the evacuation of solid cores was mainly driven by the minimization of overall surface energy. The hollow nanostructures exhibited enhanced photocatalytic activity by means of hydrogen evolution from methanol solution which is attributed to their unique structural features.