Photocatalytic Activity of a Multicomponent System Assembled within Zeolites: Case of 2,4,6-Triphenylpyrylium or Ruthenium Tris(bipyridyl) Photosensitizers and Titanium Dioxide Relays within Zeolite Y

摘要

Samples of zeolite Y containing 2,4,6-triphenylpyrylium or tris(bipyridyl)ruthenium(II) have been prepared and their photophysical and photochemical properties compared to those of the same samples containing encapsulated nanoscopic TiO_2 clusters as relays. The emission of encapsulated Ru(bpy)_3~(2+) and TP~+ photolumophores undergoes static quenching in the presence of codoped TiO_2 clusters. This is the expected behavior for systems, where photosensitizer and relay lack diffusional mobility. Time-resolved diffuse reflectance laser flash photolysis shows the transient generation of TP~* pyranyl radical and Ru(bpy)_3~(3+), upon irradiation of TP~+ and Ru(bpy)_3~(3+) in the presence of TiO_2, respectively. This provides firm support for the occurrence of photoinduced electron transfer between excited TP~+ as acceptor and TiO_2 clusters as donors and from Ru(bpy)_3~(2+) to the conduction band of TiO_2. Using the photoinactivation of horseradish peroxidase as a test reaction in aqueous medium, a synergism has been found with respect to the activity of Ru(bpy)_3~(2+) or TP~+ photocatalysts when incorporated inside the supercages of zeolite Y in the presence of TiO_2 nanoclusters.