Anatase has a larger band gap than rutile TiO2. While this reduces the light that can be absorbed, it may raise
the valence band maximum to higher energy levels relative to redox potentials of adsorbed molecules. This
increases the oxidation ‘power’ of electrons and facilitates electron transfer from the TiO2 to adsorbed
molecules13. This explanation has also been expanded to explain surface orientation dependent activities by
suggesting that different surfaces exhibit different band gaps14