title: An exceptionally fast homogeneous carbon-free cobalt-based water oxidation catalyst.
abstract: An all-inorganic, oxidatively and thermally stable, homogeneous water oxidation catalyst based on redox-active (vanadate(V)-centered) polyoxometalate ligands, Na10[Co4(H2O)2(VW9O34)2]·35H2O (Na101-V2, sodium salt of the polyanion 1-V2), was synthesized, thoroughly characterized and shown to catalyze water oxidation in dark and visible-light-driven conditions. This synthetic catalyst is exceptionally fast under mild conditions (TOF > 1 × 10(3) s(-1)). Under light-driven conditions using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, 1-V2 exhibits higher selectivity for water oxidation versus bpy ligand oxidation, the final O2 yield by 1-V2 is twice as high as that of using [Co4(H2O)2(PW9O34)2](10-) (1-P2), and the quantum efficiency of O2 formation at 6.0 μM 1-V2 reaches ∼68%. Multiple experimental results (e.g., UV-vis absorption, FT-IR, (51)V NMR, dynamic light scattering, tetra-n-heptylammonium nitrate-toluene extraction, effect of pH, buffer, and buffer concentration, etc.) confirm that the polyanion unit (1-V2) itself is the dominant active catalyst and not Co(2+)(aq) or cobalt oxide.
authors.affiliation: Department of Chemistry and ‡Emerson Center for Scientific Computation, Emory University , 1515 Dickey Dr., Atlanta, Georgia 30322, United States .
authors.forename: Hongjin
authors.initials: H
authors.lastname: Lv
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.forename: Yurii V
authors.initials: YV
authors.lastname: Geletii
authors.forename: James W
authors.initials: JW
authors.lastname: Vickers
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Sumliner
authors.forename: Djamaladdin G
authors.initials: DG
authors.lastname: Musaev
authors.forename: Paul
authors.initials: P
authors.lastname: Kögerler
authors.forename: Petro F
authors.initials: PF
authors.lastname: Zhuk
authors.forename: John
authors.initials: J
authors.lastname: Bacsa
authors.forename: Guibo
authors.initials: G
authors.lastname: Zhu
authors.forename: Craig L
authors.initials: CL
authors.lastname: Hill