  Titanium dioxide is a photocatalytic substance of great practical importance.
However, with its bandgap in the ultraviolet (UV) regime, native forms
(undoped) of TiO2 generally exhibits poor photocatalytic activities under
visible light. Here we report a facile one-step low-temperature method to treat
native TiO2 with NaH in a solution-based protocol. The NaH treatment
effectively induces the Ti(III) species and oxygen vacancies into the TiO2 host
lattice, and enables the bandgap of TiO2 to be conveniently adjusted from the
UV region to the red end of the visible spectrum. The modified TiO2 exhibited
significantly enhanced photocatalytic capability under visible light, and lead
to faster photo-degradation of organic chemical material. Compared with other
ways to reduce the bandgap of TiO2, the approach reported here provides unique
advantages for safe, large-scale and economic production of narrow-bandgap TiO2
materials.
