Photocatalytic activation of CO2 under visible light by rhenium complex encapsulated in molecular sieves

The photocatalytic activation of CO2 over molecular sieve-encapsulated cati onic rhenium complex has been investigated under visible light (lambda >350 nm). The cationic rhenium complex, [Re(I)(CO)(3)(bpy)(py)](+)(bpy=2,2'-bip yridine, py=pyridine), has been encapsulated by ion-exchange method using t he aqueous solution of [Re(I)(CO)(3) (bpy)(py)]+PF6- into the microporous N aY and the mesoporous AlMCM-41 molecular sieve acting as supramolecular het erogeneous host. To confirm the encapsulation of [Re(I)(CO)(3)(bpy)(py)](+) into the pores of molecular sieve, Xe-NMR and FT-IR spectroscopies have be en applied before and after the [Re(I)(CO)(3)(bpy)(py)](+) encapsulation. T o investigate the photophysical and photochemical properties, molecular sie ve-encapsulated cationic rhenium complex has been studied by UV-Visible dif fuse reflectance spectroscopy (UV-DRS) with photoirradiation (lambda >350 n m) at room temperature. By monitoring the photoreaction of CO2 over the pho tocatalysts, the conversion of CO2 into CO and carbonate species has been o bserved by using in-situ FT-IR and time-resolved mass spectroscopy. From th e experimental results, the photocatalytic activation mechanism of CO2 on t he catalyst under visible light (lambda >350 nm) could be proposed via the photo-induced reaction of two electrons and two protons, resulting from wat er decomposition.