Nanostructured VO2 photocatalysts for hydrogen production.

Vanadium dioxide (VO(2)) is a well-known semiconductor material with a band gap of 0.7 eV, and is seldom used as a photocatalyst. We report here a new crystal structure for nanostructured VO(2), with body-centered-cubic (bcc) structure and a large optical band gap of approximately 2.7 eV, which surprisingly shows excellent photocatalytic activity in hydrogen production. The bcc VO(2) phase exhibited a high quantum efficiency of approximately 38.7% when synthesized as nanorods. Using films of the aligned VO(2) nanorods, the hydrogen production rate can be tuned by varying the incident angle of UV light on the films and reaches a high rate of 800 mmol/m(2)/h from a mixture of water and ethanol under UV light, at a power density of approximately 27 mW/cm(2), allowing possible commercial application of this material as photoassisted hydrogen generators.