A two-dimensional phase of TiO2 with a reduced bandgap

Abstract

Titanium dioxide is the prototypical transition metal oxide photocatalyst. However, the larger than 3 eV bandgap of common bulk phases of TiO2 limits its light absorption to UV light, making it inefficient for solar energy conversion. Attempts at increasing visible light activity by narrowing the bandgap of TiO2 through doping have proven difficult, because of defect-induced charge trapping and recombination sites of photo-excited charge carriers. Here, we report the existence of a dopant-free, pure TiO2 phase with a narrow bandgap. This new pure TiO2 phase forms on the surface of rutile TiO2(011) by oxidation of bulk titanium interstitials. We measure a bandgap of only ~2.1 eV for this new phase, matching it closely with the energy of visible light. The ability of TiO2 photocatalysts to absorb solar light has so far been limited to the UV because of their large bandgap. Now, a surface phase of TiO2 that possess a narrower bandgap closely matching the visible light energy has been synthesized at the surface of pure rutile TiO2(011) faces.

Cite this article

Tao, J., Luttrell, T. & Batzill, M. A two-dimensional phase of TiO₂ with a reduced bandgap. Nature Chem 3, 296–300 (2011). https://doi.org/10.1038/nchem.1006

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