TY  - JOUR
AU  - Wiegmann, Tim
AU  - Pacheco, Ivan
AU  - Reikowski, Finn
AU  - Stettner, Jochim
AU  - Qiu, Canrong
AU  - Bouvier, Mathilde
AU  - Bertram, Manon
AU  - Faisal, Firas
AU  - Brummel, Olaf
AU  - Libuda, Jörg
AU  - Drnec, Jakub
AU  - Allongue, Philippe
AU  - Maroun, Fouad
AU  - Magnussen, Olaf
TI  - Operando Identification of the Reversible Skin Layer on Co<sub>3</sub>O<sub>4</sub> as a Three-Dimensional Reaction Zone for Oxygen Evolution
JO  - ACS catalysis
VL  - 12
SN  - 2155-5435
CY  - Washington, DC
PB  - ACS
M1  - PUBDB-2022-01347
SP  - 3256 - 3268
PY  - 2022
AB  - Co oxides and oxyhydroxides have been studied extensively in the past as promising electrocatalysts for the oxygen evolution reaction (OER) in neutral to alkaline media. Earlier studies showed the formation of an ultrathin CoO<sub>x</sub>(OH)<sub>y</sub> skin layer on Co<sub>3</sub>O<sub>4</sub> at potentials above 1.15 V vs reversible hydrogen electrode (RHE), but the precise influence of this skin layer on the OER reactivity is still under debate. We present here a systematic study of epitaxial spinel-type Co<sub>3</sub>O<sub>4</sub> films with defined (111) orientation, prepared on different substrates by electrodeposition or physical vapor deposition. The OER overpotential of these samples may vary up to 120 mV, corresponding to two orders of magnitude differences in current density, which cannot be accounted for by differences in the electrochemically active surface area. We demonstrate by a careful analysis of operando surface X-ray diffraction measurements that these differences are clearly correlated with the average thickness of the skin layer. The OER reactivity increases with the amount of formed skin layer, indicating that the entire three-dimensional skin layer is an OER-active interphase. Furthermore, a scaling relationship between the reaction centers in the skin layer and the OER activity is established. It suggests that two lattice sites are involved in the OER mechanism.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000783841900001
C6  - pmid:35359579
DO  - DOI:10.1021/acscatal.1c05169
UR  - https://bib-pubdb1.desy.de/record/475499
ER  -