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

Dye-sensitized H 2 evolution photocatalysts have attracted considerable attention as promising systems for the photochemical generation of H 2 from water. In this study, to mimic the reaction field of natural photosynthesis artificially, we synthesized a hydrophobic Ru(II) dye-sensitized Pt-TiO 2 nanoparticle photocatalyst, RuC 9 @Pt-TiO 2 ( RuC 9 = [Ru(dC 9 bpy) 2 (H 4 dmpbpy)] 2+; dC 9 bpy = 4,4′-dinonyl-2,2′-bipyridine, H 4 dmpbpy = 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 H 2 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 RuC 9 @Pt-TiO 2 nanoparticles in the DPPC bilayer vesicles is a key factor in achieving enhanced photocatalytic H 2 production activity in aqueous solution.