title: EPR evidence for Co(IV) species produced during water oxidation at neutral pH.
abstract: Thin-film water oxidation catalysts (Co-Pi) prepared by electrodeposition from phosphate electrolyte and Co(NO(3))(2) have been characterized by electron paramagnetic resonance (EPR) spectroscopy. Co-Pi catalyst films exhibit EPR signals corresponding to populations of both Co(II) and Co(IV). As the deposition voltage is increased into the region where water oxidation prevails, the population of Co(IV) rises and the population of Co(II) decreases. The changes in the redox speciation of the film can also be induced, in part, by prolonged water oxidation catalysis in the absence of additional catalyst deposition. These results provide spectroscopic evidence for the formation of Co(IV) species during water oxidation catalysis at neutral pH.
authors.affiliation: Department of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616-0935, USA.
authors.forename: J Gregory
authors.initials: JG
authors.lastname: McAlpin
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Surendranath
authors.forename: Mircea
authors.initials: M
authors.lastname: Dinca
authors.forename: Troy A
authors.initials: TA
authors.lastname: Stich
authors.forename: Sebastian A
authors.initials: SA
authors.lastname: Stoian
authors.forename: William H
authors.initials: WH
authors.lastname: Casey
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Nocera
authors.forename: R David
authors.initials: RD
authors.lastname: Britt