title: Surface Interrogation Scanning Electrochemical Microscopy of Ni(1-x)Fe(x)OOH (0 < x < 0.27) Oxygen Evolving Catalyst: Kinetics of the "fast" Iron Sites.
abstract: Nickel-iron mixed metal oxyhydroxides have attracted significant attention as an oxygen evolution reaction (OER) catalyst for solar fuel renewable energy applications. Here, we performed surface-selective and time-dependent redox titrations to directly measure the surface OER kinetics of Ni(IV) and Fe(IV) in NiOOH, FeOOH, and Ni(1-x)Fe(x)OOH (0 < x < 0.27) electrodes. Most importantly, two types of surface sites exhibiting "fast" and "slow" kinetics were found, where the fraction of "fast" sites in Ni(1-x)Fe(x)OOH matched the iron atom content in the film. This finding provides experimental support to the theory-proposed model of active sites in Ni(1-x)Fe(x)OOH. The OER rate constant of the "fast" site was 1.70 s(-1) per atom.
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Hyun S
authors.initials: HS
authors.lastname: Ahn
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Bard