Visible-light photocatalytic activity of TiO2−x by heat treatment and plasma-heat treatment

The partial reduction of TiO2 was attempted by heat treatment and plasma-heat treatment and it was carried out to investigate the photocatalytic characteristics of partially reduced TiO2 (TiO2−x) in the visible-light region. As a result, the plasma-heat treatment shows significantly stronger than the heat treatment for the visible-light photocatalytic activity of TiO2. The red-shifted absorption bands in the visible-light region of TiO2−x by plasma-heat treatment gave broader than one by heat treatment. The TiO2−x by heat treatment and plasma-heat treatment was changed white to beige color, and white to navy, respectively.