Characterization of a composite photocatalyst

Low loading of TiO2 on the zeolite ZSM-5 produced a photocatalyst of high e fficiency, especially with efficient light harvesting.(7) Comparison of 90 degrees pulse Si-29 NMR spectra with H-1-Si-29 CP-MAS spectra allows measur ement of -OH displaced from the zeolite surface by Si-O-Ti chemisorption. T he coverage by 2.5 wt % TiO2 is 16-18% of the BET surface area. A theoretic al 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 ph ase without further -OH displacement and increase of the coverage of the su rface. Energy filtered TEM shows that TiO2 growth occurs at irregularities on the ZSM-5 surface.