Band gap engineering of double-cation-impurity-doped anatase-titania for visible-light photocatalysts: a hybrid density functional theory approach

In this study, we have used cation-passivated codoping of Nb with Ga/In and also of W with Zn/Cd to modulate the band structure of anatase-TiO(2) to extend absorption to longer visible-light wavelengths. We adopted generalized Kohn-Sham theory with the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional for exchange and correlation. It has been found that (W, Cd)-doped TiO(2) should be a strong candidate for visible-light photocatalyst materials owing to the largest extent of band gap narrowing and the formation of continuum band, without movement of the valence band. It is argued that this design principle for band-edge modification can also be applied to other wide-band-gap semiconductors.