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

Dye-sensitizedH(2) evolution photocatalysts have attractedconsiderable attention as promising systems for the photochemicalgeneration of H-2 from water. In this study, to mimic thereaction field of natural photosynthesis artificially, we synthesizeda hydrophobic Ru-(II) dye-sensitized Pt-TiO2 nanoparticlephotocatalyst, RuC ( 9 )@Pt-TiO2 (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), andintegrated 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 solutionenhanced by more than three times in the presence of DPPC vesicles(apparent quantum yield = 2.11%), whereas such a significant enhancementwas hardly observed when the vesicle formation was omitted. Theseresults indicate that the highly dispersed state of the hydrophobic RuC ( 9 )@Pt-TiO2 nanoparticlesin the DPPC bilayer vesicles is a key factor in achieving enhancedphotocatalytic H-2 production activity in aqueous solution.