title: Efficient water oxidation catalysts based on readily available iron coordination complexes.
abstract: Water oxidation catalysis constitutes the bottleneck for the development of energy-conversion schemes based on sunlight. To date, state-of-the-art homogeneous water oxidation catalysis is performed efficiently with expensive, toxic and earth-scarce transition metals, but 3d metal-based catalysts are much less established. Here we show that readily available, environmentally benign iron coordination complexes catalyse homogeneous water oxidation to give O(2), with high efficiency during a period of hours. Turnover numbers >350 and >1,000 were obtained using cerium ammonium nitrate at pH 1 and sodium periodate at pH 2, respectively. Spectroscopic monitoring of the catalytic reactions, in combination with kinetic studies, show that high valent oxo-iron species are responsible for the O-O forming event. A systematic study of iron complexes that contain a broad family of neutral tetradentate organic ligands identifies first-principle structural features to sustain water oxidation catalysis. Iron-based catalysts described herein open a novel strategy that could eventually enable sustainable artificial photosynthetic schemes.
authors.affiliation: Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Spain. Julio.lloret@udg.edu
authors.forename: Julio Lloret
authors.initials: JL
authors.lastname: Fillol
authors.forename: Zoel
authors.initials: Z
authors.lastname: Codolà
authors.forename: Isaac
authors.initials: I
authors.lastname: Garcia-Bosch
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Pla
authors.forename: Miquel
authors.initials: M
authors.lastname: Costas
mesh_terms: D002384:Catalysis; D002563:Cerium / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010504:Periodic Acid / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D009566:Nitrates; D010087:Oxides; C532772:cerium(IV) ammonium nitrate; D014867:Water; D010504:Periodic Acid; C066318:perferryl iron; D002563:Cerium; C009288:metaperiodate; D007501:Iron