Journal of Physical Chemistry B, Vol.104, No.36, 8679-8684, 2000
Characterization of a composite photocatalyst
Low loading of TiO2 on the zeolite ZSM-5 produced a photocatalyst of high efficiency, especially with efficient light harvesting.(7) Comparison of 90 degrees pulse Si-29 NMR spectra with H-1-Si-29 CP-MAS spectra allows measurement of -OH displaced from the zeolite surface by Si-O-Ti chemisorption. The coverage by 2.5 wt % TiO2 is 16-18% of the BET surface area. A theoretical monolayer of anatase TiO2 loaded to 2.5 wt % is calculated to cover 10%-20% of the BET surface, depending upon the orientation of the anatase unit cell. Loading TiO2 above 2.5 wt % leads to further growth of the titania phase without further -OH displacement and increase of the coverage of the surface. Energy filtered TEM shows that TiO2 growth occurs at irregularities on the ZSM-5 surface.