Studies on the enhanced photocatalytic hydrogen evolution over Pt/PEG-modified TiO2 photocatalysts

Polyethylene glycol (PEG) with different average molecular weight (400, 2000, 6000, 20 000) was used as a templating reagent to synthesize PEG-modified TiO2 photocatalyst by sol-gel method. This study revealed that PEG molecules of appropriate size acted significantly in well-controlled crystal growth and the enlargement of surface area via the pore-forming function. The Pt cocatalyst was loaded by the photochemical deposition method to investigate its photocatalytic activity for H-2 evolution from an aqueous ethanol solution. The Pt/PEG-modified TiO2 photocatalyst showed higher photocatalytic activity than Pt/unmodified TiO2 and Pt/Degussa P25-TiO2, among which Pt/PEG6000-TiO2 demonstrated the highest activity with an average H-2 evolution rate of 1615 mu mol h(-1). Therefore, the utilization of PEG to modify the microstructure of TiO2 was proved to be an efficient way to acquire improved photocatalytic performance. The extended studies of the reaction at different temperatures and from a series of hydrocarbon sacrificial reagents were also performed over Pt/PEG6000-TiO2. The results were helpful to obtain further understanding of the photocatalytic reaction. (C) 2008 Published by Elsevier Ltd. on behalf of International Association for Hydrogen Energy.