posted on 2020-03-19, 13:03authored byYan Duan, Nicolas Dubouis, Jiaqiang Huang, Daniel Alves Dalla Corte, Vanessa Pimenta, Zhichuan J. Xu, Alexis Grimaud
Recent studies have
revealed the critical role played by the electrolyte
composition on the oxygen evolution reaction (OER) kinetics on the
surface of highly active catalysts. While numerous works were devoted
to understand the effect of the electrolyte composition on the physical
properties of the catalysts’ surface, very little is known
yet about its exact impact on the OER kinetics parameters. In this
work, we reveal that the origin for the electrolyte-dependent OER
activity for Co-based catalysts originates from two different effects.
Increasing the alkaline electrolyte concentration for La1–xSrxCoO3−δ perovskites with x > 0 and for amorphous CoOOH
increases the pre-exponential factor, which can be explained either
by an increase of the concentration of active sites or by a change
in the entropy of activation. However, changing the alkali cation
results in a decrease of the apparent activation enthalpy for Fe-containing
amorphous films, traducing a change in intermediates’ binding
energies.