TiO2/Y-zeolite encapsulating intramolecular charge transfer molecules:: a new photocatalyst for photoreduction of methyl orange in aqueous medium

An intramolecular charge transfer (ICT) molecule, p-N,N'-dimethylaminobenzoic acid (DMABA) has been adsorbed onto nanoscale pores of TiO2/Y-zeolite and its spectroscopic properties have been studied. The DMABA adsorbed on TiO2/Y-zeolite shows dual emission band originated from the locally excited state and the ICT state. The ICT emission of DMABA in TiO2/Y-zeolite is very weak as compared with that observed in homogeneous solution and other heterogeneous systems. This is attributed to an efficient electron donation from the excited singlet state of DMABA to the conduction band of TiO2 on the zeolite. The conduction band electron of TiO2 can be transported through the frame as demonstrated by the photocatalytic reduction of methyl orange dissolved in aqueous solution. The quantum efficiency of the photocatalytic reduction of methyl orange is about 34% using 320 nm light. The DMABA is little destroyed during the degradation of methyl orange. (C) 2001 Elsevier Science B.V. All rights reserved.