Dispersion and Structure Studies of Molybdenum Oxide on Anatase TiO_2

摘要

X-ray photoelectron spectroscopy(XPS) and extended X-ray absorption fine structure(EXAFS) were used to characterize the structure of the mixture of molybdenum oxide and anatase calcined at 723 K. The results indicate that molybdenum oxide can disperse onto the surface of anatase(TiO 2) and the dispersion threshold is 11.2 mg in per gram of MoO 3 or 4.8 Mo atoms/nm 2 TiO 2. When the content of MoO 3 is below the dispersion threshold, MoO 3 species is in highly dispersed state interacting strongly with TiO 2 support and in discrete tetrahedral coordination, [MoO 4], on the surface of TiO 2. When the MoO 3 loading is above this value, MoO 3 exists in both dispersed phase and crystalline phase. MoO 3 in dispersed phase is still a discrete [MoO 4] tetrahedron; MoO 3 in crystal phase is in octahedral coordination.