Hard template synthesis of crystalline mesoporous anatase TiO2 for photocatalytic hydrogen evolution

Abstract

Mesoporous crystalline anatase TiO₂ has been synthesized by using the nanocasting method with mesoporous silica KIT-6 as the hard template and titanium alkoxide as the precursor. Three key synthetic parameters play important roles in the formation of crystalline porous materials. These are precursor/template ratios, calcination temperatures and immersion time (in 2 M NaOH to remove template). The synthesized materials are characterized with powder X-ray diffraction (XRD), N₂ adsorption–desorption isotherm analysis and energy-dispersive X-ray spectroscopy (EDX) elemental analysis. Owing to the template confinement effect, mesoporous anatase TiO₂ instead of rutile phase was obtained at the calcination temperature of 750 °C. Materials with a surface area as high as 207 m² g⁻¹ have been obtained. The photocatalytic activities of the as-prepared mesoporous TiO₂ were studied with a loading of 0.5% Pt. The materials with higher surface areas showed higher H₂ evolution activities. The H₂ evolution activity of the mesoporous anatase sample prepared under optimal conditions was 5.5 times higher than that of bulk anatase TiO₂. The work represents a step forward in the development of highly efficient photocatalysts based on crystalline high surface area porous materials and our results indicate that the hard template method may be an effective method to achieve this goal.