title: Triplet state photosensitization of nanocrystalline metal oxide electrodes by zinc-substituted cytochrome c: application to hydrogen evolution.
abstract: The interfacing of nanostructured semiconductor photoelectrodes with redox proteins is an innovative approach to the development of artificial photosynthetic systems. In this paper, we have investigated the photoinduced electron-transfer reactions of zinc-substituted cytochrome c, ZnCyt-c, immobilized on mesoporous, nanocrystalline metal oxide electrodes. Efficient electron injection from the triplet state of ZnCyt-c is observed into TiO(2) electrodes (t(50%) approximately 100 micros) resulting in a long-lived charge-separated state (lifetime of up to 0.4 s). Further studies were undertaken as a function of electrolyte pH and metal oxide employed. Optimum yield of a long-lived charge-separated state was observed employing TiO(2) electrodes at pH 5, consistent with our previous studies of analogous dye-sensitized metal oxide electrodes. The addition of EDTA as a sacrificial electron donor to the electrolyte resulted in efficient photogeneration of molecular hydrogen, with a quantum yield per one absorbed photon of 10 +/- 5%.
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Yeni
authors.initials: Y
authors.lastname: Astuti
authors.forename: Emilio
authors.initials: E
authors.lastname: Palomares
authors.forename: Saif Ahmed
authors.initials: SA
authors.lastname: Haque
authors.forename: James Robert
authors.initials: JR
authors.lastname: Durrant
mesh_terms: D003460:Crystallization; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004492:Edetic Acid / Q000737:chemistry; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D011522:Protons; D014025:Titanium / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D008670:Metals; D010087:Oxides; D011522:Protons; C050095:zinc cytochrome c; C009495:titanium dioxide; D006859:Hydrogen; D045304:Cytochromes c; D004492:Edetic Acid; D014025:Titanium