Hydrogen Production from Hydrophobic Ruthenium Dye-Sensitized TiO2 Photocatalyst Assisted by Vesicle Formation

Dye-sensitized H2 evolution photocatalysts have attracted considerable attention as promising systems for the photochemical generation of H2 from water. In this study, to mimic the reaction field of natural photosynthesis artificially, we synthesized a hydrophobic Ru(II) dye-sensitized Pt-TiO2 nanoparticle photocatalyst, RuC9@Pt-TiO2 (RuC9 = [Ru(dC9bpy)2(H4dmpbpy)]2+; dC9bpy = 4,4′-dinonyl-2,2′-bipyridine, H4dmpbpy = 4,4′-dimethyl phosphonic acid-2,2′-bipyridine), and integrated it into 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid bilayer vesicle membranes. The photocatalytic H2 production activity in 0.5 M l-ascorbic acid aqueous solution enhanced by more than three times in the presence of DPPC vesicles (apparent quantum yield = 2.11%), whereas such a significant enhancement was hardly observed when the vesicle formation was omitted. These results indicate that the highly dispersed state of the hydrophobic RuC9@Pt-TiO2 nanoparticles in the DPPC bilayer vesicles is a key factor in achieving enhanced photocatalytic H2 production activity in aqueous solution.