Mesoporous TiO₂ nanostructures: A route to minimize Pt loading on titania photocatalysts for hydrogen production

Mesostructured TiO₂ nanocrystals have been prepared using Pluronic F127 as the structure-directing agent. Platinum nanoparticles at different contents (0.1-1.0 wt%) have been photochemically deposited onto the mesoporous TiO₂. TEM investigation of 0.2 wt% Pt/TiO₂ calcined at 450 °C reveals that the TiO₂ particles are quite uniform in size and shape with the particle sizes of TiO₂ and Pt being 10 and 3 nm, respectively. The photocatalytic activities of the Pt loaded TiO₂ have been assessed and compared with those of nonporous commercial Pt/TiO₂-P25 by determining the rates and the photonic efficiencies of molecular hydrogen production from aqueous methanol solutions. The results show that the amount of hydrogen evolved on Pt/TiO₂-450 at low Pt loading (0.2 wt%) is three times higher than that evolved on Pt/TiO₂-P25 and twelve times higher than that evolved on Pt/TiO ₂-350. Despite the BET surface area of the TiO₂-450 photocatalyst being 3.5 times higher than that of TiO₂-P25, a 60% smaller amount of the Pt co-catalyst is required to obtain the optimum photocatalytic hydrogen production activity. The reduced Pt loading on the mesoporous TiO₂ will be important both from a commercial and an ecological point of view.