Pd-Ti-MCM-48 cubic mesoporous materials for solar simulated hydrogen evolution.

A facile synthetic method (in ≥4 h) for simultaneously loading high amts. of TiO2 (Si/Ti = 3) and Pd0 co-catalyst (0.1% per g of total catalyst) in cubic mesoporous MCM-48 material was developed at room temp. The solar simulated photocatalytic H evolution from photocatalysts contg. Pd0 and TiO2 nanoclusters in periodic cubic MCM-48 and aperiodic mesoporous SiO2 was compared. The periodicity of the mesoporous SiO2 support, the oxidn. state of Pd, the location and dispersion of Pd0 have a significant impact on the photocatalytic activity. Periodic cubic MCM-48 mesoporous SiO2 contg. Pd0 in close contact with TiO2 exhibit superior H evolution rates compared to Pd0-TiO2 contg. aperiodic mesoporous SiO2. The highly ordered and open 3-dimensional mesoporous cubic MCM-48 support has high surface area and facilitate good dispersion and close contact of TiO2 and Pd0. At very low loadings of 0.1% of Pd, H yield is 560 μ mol h-1, which is among the highest reported in the literature for Pd0 contg. TiO2 based materials under solar simulated conditions. Probably the pore architecture of the support is also an important parameter that governs the photocatalytic activity. The Pd0-mesoporous materials in general possess higher activity than Pd2+ contg. mesoporous materials. The photocatalysts were extensively characterized by a variety of techniques such as powder XRD, N sorption anal., transmission and scanning electron microscopic studies, photoluminescence, diffuse reflectance spectroscopy (DRS), CO Chemisorption, and XPS. [on SciFinder(R)]