Tuning the Electronic and Molecular Structures of Catalytic Active Sites with Titania Nanoligands

A series of supported 1−60% TiO2/SiO2 catalysts were synthesized and subsequently used to anchor surface VO x redox and surface WO x acid sites. The supported TiO x , VO x , and WO x phases were physically characterized with TEM, in situ Raman and UV−vis spectroscopy, and chemically probed with in situ CH3OH-IR, CH3OH-TPSR and steady-state CH3OH dehydration. The CH3OH chemical probe studies revealed that the surface VO x sites are redox in nature and the surface WO x sites contain acidic character. The specific catalytic activity of surface redox (VO4) and acidic (WO5) sites coordinated to the titania nanoligands are extremely sensitive to the degree of electron delocalization of the titania nanoligands. With decreasing titania domain size,