title: Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting.
abstract: In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.
authors.affiliation: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
authors.forename: Dirk
authors.initials: D
authors.lastname: Mersch
authors.affiliation: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
authors.forename: Chong-Yong
authors.initials: CY
authors.lastname: Lee
authors.affiliation: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
authors.forename: Jenny Zhenqi
authors.initials: JZ
authors.lastname: Zhang
authors.affiliation: ‡Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K.
authors.forename: Katharina
authors.initials: K
authors.lastname: Brinkert
authors.affiliation: §Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble Alpes, 38044 Grenoble, France.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fontecilla-Camps
authors.affiliation: ‡Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K.
authors.forename: A William
authors.initials: AW
authors.lastname: Rutherford
authors.affiliation: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
authors.forename: Erwin
authors.initials: E
authors.lastname: Reisner
mesh_terms: D002384:Catalysis; D002849:Chromatography, Gas; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry*; D008027:Light; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry / Q000379:methods*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D020560:Proteobacteria / Q000378:metabolism; D012993:Solar Energy; D046940:Synechococcus / Q000378:metabolism; D013816:Thermodynamics; D017971:Tin Compounds / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D045332:Photosystem II Protein Complex; D017971:Tin Compounds; D014867:Water; C109984:indium tin oxide; D006859:Hydrogen; D006864:Hydrogenase; D010100:Oxygen