C. Ooka et al., Crystallization of hydrothermally treated TiO2 pillars in pillared montmorillonite for improvement of the photocatalytic activity, J MAT CHEM, 9(11), 1999, pp. 2943-2952
A novel pillared clay, i.e. pillared montmorillonite with crystallized TiO2
, has been developed as a highly active photocatalyst. The TiO2 pillars in
pillared montmorillonite were crystallized to anatase by hydrothermal treat
ment, while the porosity of the pillared clay was retained. The size of the
crystallized TiO2 pillars and the average pore diameter showed good agreem
ent, and both sizes could be controlled in the range ca. 40-90 Angstrom by
changing the treatment conditions. The photocatalytic properties of the TiO
2 pillars were investigated in the degradation of trichloroethylene in wate
r. The hydrothermal crystallization enhanced the catalytic activity both pe
r unit weight of TiO2 and per exposed unit surface area of TiO2. The cataly
tic activity of the TiO2 pillars was also enhanced by quantum-size effects:
as the TiO2 pillar size decreased, the pillared montmorillonites exhibited
higher catalytic activity and showed larger blue-shifts in their UV absorp
tion spectra.