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Reactive Electrophilic OI- Species Evidenced in High-Performance Iridium Oxohydroxide Water Oxidation Electrocatalysts.


ABSTRACT: Although quasi-amorphous iridium oxohydroxides have been identified repeatedly as superior electrocatalysts for the oxygen evolution reaction (OER), an exact description of the performance-relevant species has remained a challenge. In this context, we report the characterization of hydrothermally prepared iridium(III/IV) oxohydroxides that exhibit exceptional OER performances. Holes in the O?2p states of the iridium(III/IV) oxohydroxides result in reactive OI- species, which are identified by characteristic near-edge X-ray absorption fine structure (NEXAFS) features. A prototypical titration reaction with CO as a probe molecule shows that these OI- species are highly susceptible to nucleophilic attack at room temperature. Similarly to the preactivated oxygen involved in the biological OER in photosystem?II, the electrophilic OI- species evidenced in the iridium(III/IV) oxohydroxides are suggested to be precursors to species involved in the O-O bond formation during the electrocatalytic OER. The CO titration also highlights a link between the OER performance and the surface/subsurface mobility of the OI- species. Thus, the superior electrocatalytic properties of the iridium (III/IV) oxohydroxides are explained by their ability to accommodate preactivated electrophilic OI- species that can migrate within the lattice.

SUBMITTER: Massue C 

PROVIDER: S-EPMC5813174 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Reactive Electrophilic O<sup>I-</sup> Species Evidenced in High-Performance Iridium Oxohydroxide Water Oxidation Electrocatalysts.

Massué Cyriac C   Pfeifer Verena V   van Gastel Maurice M   Noack Johannes J   Algara-Siller Gerardo G   Cap Sébastien S   Schlögl Robert R  

ChemSusChem 20171108 23


Although quasi-amorphous iridium oxohydroxides have been identified repeatedly as superior electrocatalysts for the oxygen evolution reaction (OER), an exact description of the performance-relevant species has remained a challenge. In this context, we report the characterization of hydrothermally prepared iridium(III/IV) oxohydroxides that exhibit exceptional OER performances. Holes in the O 2p states of the iridium(III/IV) oxohydroxides result in reactive O<sup>I-</sup> species, which are ident  ...[more]

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