Visible light photodegradation of phenol on MWNT-TiO2 composite catalysts prepared by a modified sol-gel method

A synergetic effect could be ascribed to MWNT acting as photosensitizer in a photocatalytic process. This can be described in terms of (a) photo-induced electron transfer into the TiO2 conduction band following light absorption by MWNT. The catalytic nature of the process demands that (b) back electron transfer occurs from the valence band of TiO2 with formation of a hole, which is neutralized by oxidation of the adsorbed OH−.