Photosensitization of different ruthenium(II) complex dyes on TiO2 for photocatalytic H2 evolution under visible-light

Hydrogen production over dye-sensitized Pt/P25 under visible-light irradiation was investigated by using methanol or TEOA as an electron donor. Ru2(bpy)4L1–PF6 shows the best photosensitization due to its largest conjugation system, widest range of visible-light and ‘antenna effect’ among the used three Ru(II)-bipyridyl dyes. Ru2(bpy)4L1–PF6 loosely linked with TiO2 also exhibit more steady and higher increases in H2 evolution upon prolonging the irradiation time than the tightly linked N719. The dynamic equilibrium between the linkage of ground dye and divorce of oxidized dye from TiO2 can enhance the electron-injection and hinder the backward transfer, and then improve the H2 evolution efficiency.