“…The reaction of this electron-hole pair with a variety of electron acceptors and donors, and the electron-hole recombination processes, have been well studied [7,8]. The formation of cation radicals of organic substrates, following electron transfer to the excited semiconductor has been unambiguously characterized both from product analysis [9] and by spectroscopic studies [10]. The trapped hole in TiO 2 can lead to the formation of hydroxyl radicals, which can abstract a hydrogen atom from weak C-H bonds and reacts with multiple bonds, including reactions with aromatic systems, leading to the formation of free radicals.…”