Photoformed electron transfer from TiO2 to metal clusters

Detection of mobile charge carriers consistent with a process involving electron transfer from TiO2 to metal particle was measured by EPR and FTIR in the presence of a hole scavenger and under UV irradiation. The main role of the metal (Ag, Au or Cu) was to scavenge the photogenerated electrons leading to an improvement in charge separation with respect to unmodified TiO2 alone, The improvement of charge separation yielded a greater number of holes that were available for surface reaction. A higher rate of reaction on the bleaching of Rhodamine 6G was measured when metal clusters were added to TiO2. Monitoring of solution pH during the degradation of the dye suggest a range of products were formed, whose nature depended both on the presence of metal and on the particular metal present. (C) 2008 Elsevier B.V. All rights reserved.