Electronic band structure, optical absorption and photocatalytic activity of anatase doped with bismuth or carbon

The electronic band structure, frequency-dependent dielectric function and absorption spectra of the anatase containing oxygen vacancy or doped with bismuth or carbon have been calculated with the aid of the pseudopotential plane-wave method. Basing on the calculated data, the available experimental data on the visible light absorption are discussed. The main conclusion is that the Bi3+ ions cannot replace the Ti4+ ions in the structure of anatase. The conclusion is confirmed by the calculations of the energy of the defect formation. The visible light absorption can be explained by the presence of the carbon impurities or additional phases, probably Bi2O3 or Bi4Ti3O12.

► The band structure of anatase containing oxygen vacancy or doped with bismuth or carbon have been calculated.
► The absorption spectra and energy formation of the Bi-defect also have been evaluated.
► The conclusion is that in anatase the Bi atoms cannot replace Ti atoms.
► So the visible part of the experimental absorption spectra has no relation to the Bi-bands in anatase.
► And this is probably associated with carbon impurities or with the accompanying Bi-containing phases.