Enhanced photocatalytic activity of a B 12 -based catalyst co-photosensitized by TiO 2 and Ru(ii) towards dechlorination.

A novel hybrid photocatalyst denoted as B 12 -TiO 2 -Ru(ii) was prepared by co-immobilizing a B 12 derivative and trisbipyridine ruthenium (Ru(bpy) 3 2+ ) on the surface of a mesoporous anatase TiO 2 microspheres and was characterized by DRS, XRD, SEM and BET et al. By using the hybrid photocatalyst, DDT was completely didechlorinated and a small part of tridechlorinated product was also detected in the presence of TEOA only after 30 min of visible light irradiation. Under simulated sunlight, the hybrid exhibited a significantly enhanced photocatalytic activity for dechlorination compared with B 12 -TiO 2 under the same condition or itself under visible light irradiation due to the additivity in the contribution of UV and visible part of the sunlight to the electron transfer. In addition, this hybrid catalyst can be easily reused without loss of catalytic efficiency. This is the first report on a B 12 -based photocatalyst co-sensitized by two photosensitizers with wide spectral response.