The utility of polycrystalline anatase TiO2 and SrTiO3 semiconductor electrodes sensitized by ruthenium(II) tris(2,2′-bipyridine-4,4′-dicarboxylic acid) (1) and by zinc tetrakis(4-carboxyphenyl)porphyrin (2) as component photoelectrodes in a multipanel array has been evaluated. The efficiency for photocurrent generation of a single sensitized electrode is decreased as the sensitizer loading on the surface is increased beyond monolayer coverage. Power curves for both sensitizers were obtained in aqueous solutions of potassium iodide, hydroquinone, hydroquinonesulfonate (potassium salt), durohydroquinone, and potassium ferrocyanide as electron donors. From stability and efficiency considerations, hydroquinone is the most appropriate electron donor among this group. The maximum quantum efficiency attained on the metal oxide coated electrodes described herein for monochromatic excitation of 1 was 41% on TiO2 (surface coverage 3.0 × 10-10 mol/cm2) and 57% on SrTiO3 (surface coverage 5.9 × 10-11 mol/cm2). With 2 at 420 nm a maximum quantum efficiency on TiO2 was 9.5% (surface coverage 1.7 × 10-10 mol/cm2) and on SrTiO3 was 27% (surface coverage 5.0 × 10-12 mol/cm2). Better efficiencies were observed with adsorbed than with chemically bonded 1. The quantitative reproducibility of the observed photocurrents was a sensitive function of the preparation and porosity of the metal oxide surface. Porous TiO2 gave better photoresponse than photodoped SrTiO3 as a photosensitized electrode. Despite these relatively high quantum efficiencies, the steady-state photocurrents produced on these sensitized electrodes were too low for practical operation in a multipanel device.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry