Visible-Light-Active Titania Photocatalysts: The Case of N-Doped s—Properties and Some Fundamental Issues
Figure 4
Schematic representation of the energy band structure of
pure and -doped anatase and rutile (energies not to scale). Note the modest
shift of 0.03 eV in of the conduction band to higher energies and the
contraction energy in the -doped rutile . represents the
energy of the dopant levels above the valence band. Higher levels of doping,
for example, three atoms per supercell, cause a small shift of to higher
energies for which is overcompensated by the presence of -derived states
just above VB, so that the excitation energy from these states
to the conduction band is reduced by <0.1 eV compared to pure anatase (
denotes the width of the valence bands). Adapted from results reported in [47].
