title: Engineered electron-transfer chain in photosystem 1 based photocathodes outperforms electron-transfer rates in natural photosynthesis.
abstract: Photosystem 1 (PS1) triggers the most energetic light-induced charge-separation step in nature and the in vivo electron-transfer rates approach 50 e(-)  s(-1)  PS1(-1). Photoelectrochemical devices based on this building block have to date underperformed with respect to their semiconductor counterparts or to natural photosynthesis in terms of electron-transfer rates. We present a rational design of a redox hydrogel film to contact PS1 to an electrode for photocurrent generation. We exploit the pH-dependent properties of a poly(vinyl)imidazole Os(bispyridine)2Cl polymer to tune the redox hydrogel film for maximum electron-transfer rates under optimal conditions for PS1 activity. The PS1-containing redox hydrogel film displays electron-transfer rates of up to 335±14 e(-)  s(-1)  PS1(-1), which considerably exceeds the rates observed in natural photosynthesis or in other semiartificial systems. Under O2 supersaturation, photocurrents of 322±19 μA cm(-2) were achieved. The photocurrents are only limited by mass transport of the terminal electron acceptor (O2). This implies that even higher electron-transfer rates may be achieved with PS1-based systems in general.
authors: Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum (Germany).
authors: Tim
authors: T
authors: Kothe
authors: Sascha
authors: S
authors: Pöller
authors: Fangyuan
authors: F
authors: Zhao
authors: Philippe
authors: P
authors: Fortgang
authors: Matthias
authors: M
authors: Rögner
authors: Wolfgang
authors: W
authors: Schuhmann
authors: Nicolas
authors: N
authors: Plumeré
mesh_terms: D057005:Bioengineering; D003432:Cross-Linking Reagents; D004579:Electron Transport; D004583:Electrons; D020100:Hydrogels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008027:Light; D010084:Oxidation-Reduction; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D045331:Photosystem I Protein Complex
keywords: bio-electrochemistry; electron transfer; pH response; photovoltaics; redox hydrogel