Sensitization of TiO2 by the MLCT Excited State of Col Coordination Compounds

Co+ coordination compounda, based on porphyrin or glyoxime ligands, anchored to TiO2 nanocrystallites interconnected in a mesoporous thin film were found to efficiently inject electrons into TiO2 when excited with visible or near-infrared light. When a cobale metalloporphysin sensitizer was employed charge separated state whose recombination kinetics were nonexponential but were first order in the concentration of TiO2 electrons. The MLCT excited state was found to inject electrons more efficiently than the pi ->pi* excited state of the present findinds provide an earth abundant metal to use in coordination compounds for sensitization of wide-band-gap semiconductor nanoparticles especially those whose conduction band edges are generally closer to the vacuum level.