Integrated Systems for Water Cleavage by Visible Light; Sensitization of TiO2 Particles by Surface Derivatization with Ruthenium Complexes

Irradiation of acidic (pH 2) solutions of RuL₃²⁺ 2Cl^? (L = diisopropyl 2,2′-bipyridine-4,4′ -dicarboxylate) in the presence of TiO₂ at 100°C leads to the loss of one bipyridyl ligand and the chemical fixation of RuL₂ at the surface of teh TiO₂ particles through formation of Ru-O-Ti bonds. These surface complexes are very stable and shift the absorption onset of TiO₂ beyond 600 mm. Efficient sensitization H₂-generation is achieved with this system beginning in the wave length domain between 590 and 665 nm. Preliminary water cleavage experiments with bifunctional TiO₂/Pt/RuO₂ redox catalyst are reported.