Hydrogen Production from Aqueous Solutions of Glycerol on TiO2/Ru-MCM-41 Photocatalysts Using Solar Light

Ru-MCM-41 molecular sieves were prepared (Si/Ru atomic ratio = 50 or 100) by a hydrothermal method and impregnated with TiO2. The materials were characterized by XRD, N2 physisorption, DRS, SEM and TEM. Their potential application to hydrogen production by photolysis of water using solar light was tested in a batch reactor using mixtures of water and glycerol (0–6.85 mol L−1) at pH varying from 1 to 11. The photocatalytic efficiency under simultaneous UV (0.05 μW cm−2) and visible light (90.07 W m−2) irradiation was compared to the activity of TiO2/MCM-41 (i.e., no Ru incorporated) and commercial Degussa TiO2 P25. The most active material was 20%TiO2/Ru-MCM-41(100) whose performance (220.6 µmol gTi −1 H2) was approximately 47 times higher than TiO2 P25. Characterization results showed the deposition of TiO2 and revealed the formation of RuO2 on the surface. Hydrogen generation was improved due to higher charge separation at the TiO2/RuO2 heterojunction and to the enhancement of visible light absorption caused by surface plasmon resonance (SPR). Hydrogen production increased with glycerol concentration, tending to stabilize around 40.3 µmol h−1 gTi −1 above 4 mol L−1 of glycerol. Hydrogen generation reached its maximum at extreme values of pH (1 and 11).