In:
ChemSusChem, Wiley, Vol. 10, No. 23 ( 2017-12-08), p. 4786-4798
Kurzfassung:
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 I− 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 O I− 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 O I− 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 O I− species. Thus, the superior electrocatalytic properties of the iridium (III/IV) oxohydroxides are explained by their ability to accommodate preactivated electrophilic O I− species that can migrate within the lattice.
Materialart:
Online-Ressource
ISSN:
1864-5631
,
1864-564X
DOI:
10.1002/cssc.201701291
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2017
ZDB Id:
2411405-4