Photochemical Hydrogen Evolution in K_4Nb_6O_(17) Semiconductor Particles Sensitized by Phosphonated Trisbipyridine Ruthenium Complexes

摘要

Three different phosphonated trisbipyridine ruthenium complexes, [(4-CH_3-4'-CH_2PO(OH)_2-2,2'-bipyridine)-(bpy)_2Ru] centre dot (PF_6)_2 (Ru-P1), [(4-CH_3-4'-CH_2PO(OH)_2-2,2'-bipyridine)3Ru] centre dot (PF_6)_2 (Ru-P2), and [(4,4'-CH_2PO-(OH)_2-2,2'-bipyridine)_3Ru] centre dot (PF_6)_2 (Ru-P3) were synthesized and their photochemical and electrochemical properties were studied. These ruthenium complexes were strongly adsorbed on the surface of the layered metal oxide semiconductor K_4Nb_6O_(17) that was partially acid-exchanged and sensitized up to pH 10, while the carboxylated ruthenium complex, (4,4'-COOH-2,2'-bipyridine)_3Ru centre dot Cl_2 (Ru-C) that was previously studied was sensitized only below pH 4. The visible light water reduction at K_4Nb_6O_(17) that was internally platinized and sensitized by these phosphonated Ru-complexes was comparatively studied using a reversible electron donor iodide.