Local structures and photocatalytic reactivities of the titanium oxide and chromium oxide species incorporated within micro- and mesoporous zeolite materials: XAFS and photoluminescence studies

Transition metal oxides (titanium, chromium oxides) photocatalysts can be designed within the cavities and frameworks of various zeolites and mesoporous molecular sieves by ion-exchange and hydrothermal synthesis. A combination of in situ XAFS and photoluminescence spectroscopic techniques has revealed that these transition metal oxide species incorporated within zeolites exist in a highly dispersed state with a tetrahedral coordination and such a high dispersion state allows them to act as efficient photocatalysts for various photocatalytic reactions. These results clearly suggest that the utilization of zeolites and mesoporous materials is one of the most promising approaches to design and development of highly efficient and effective photocatalysts with well-defined local structures at the molecular level.