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'-dimethylaminobenzo ic acid (DMABA) has been adsorbed onto nanoscale pores of TiO2/Y-zeolite an d its spectroscopic properties have been studied. The DMABA adsorbed on TiO 2/Y-zeolite shows dual emission band originated from the locally excited st ate 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 heter ogeneous systems. This is attributed to an efficient electron donation from the excited singlet state of DMABA to the conduction band of TiO2 on the z eolite. The conduction band electron of TiO2 can be transported through the frame as demonstrated by the photocatalytic reduction of methyl orange dis solved in aqueous solution. The quantum efficiency of the photocatalytic re duction of methyl orange is about 34% using 320 nm light. The DMABA is litt le destroyed during the degradation of methyl orange. (C) 2001 Elsevier Sci ence B.V. All rights reserved.