Visible-Light-Responsive Carbon Dioxide Reduction System: Rhenium Complex Intercalated into a Zirconium Phosphate Layered Matrix

The intercalation of CO2 reduction catalyst [Re(bpy)(CO)(3)Cl] (bpy=2,2-bipyridine) into a layered zirconium phosphate (Zr(HPO4)(2)H2O, -ZrP) with an interlayer distance of 10.3 angstrom was performed. XRD, IR spectroscopy, and extended X-ray absorption fine structure measurements provided strong evidence that the Re complexes were intercalated into the layered interspace without significant structural change. The visible-light photoredox system for the catalytic conversion of CO2 was constructed by using Re/ZrP as catalyst, RhodamineB as photosensitizer, and triethanolamine as a sacrificial reagent. The emission intensity of RhodamineB near =580nm decreased with increasing amount of intercalated Re complex, suggesting the occurrence of an electron transfer from RhodamineB to the Re complex. Performing the reaction with isotopic (CO2)-C-13 demonstrated that the CO produced originated mostly from CO2. Furthermore, this CO2 reduction system showed remarkable durability and could be used repeatedly without significant loss in activity.