Role of support on the photocatalytic activity of titanium oxide Original Research Article

We demonstrate an enhanced photocatalytic activity for TiO2 when it is dispersed on ZrO2 and zeolite compared to that dispersed on Al2O3 and CeO2. In these composite systems, TiO2 exists as a dispersed particulate phase and the extent of dispersion is the highest on ZrO2 support. Na–Y zeolite possesses the maximum Lewis acidity followed by ZrO2, Al2O3 and CeO2. Optical absorption property of TiO2 dispersed on ZrO2, zeolite and CeO2 is better than that of unsupported TiO2. In the above mentioned systems, photocatalytic activity of TiO2 shows a strong dependence on the surface acidity of the support. A significantly high photocatalytic activity for hydrogen generation from water–methanol mixture is observed for the TiO2–ZrO2 system. The enhanced activity of TiO2 dispersed on ZrO2 is attributed to the enhanced optical absorption and increased life time of the photogenerated charge carriers assisted by the surface acidic sites. Present study leads to a new result that a highly dispersed phase of TiO2 on a support having higher surface acidity exhibits enhanced photocatalytic activity. This strategy may be useful for the design of new catalysts yielding high photocatalytic activity. Presence of a co-catalyst like Pd metal enhances the photocatalytic activity further.