Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 13: Solid-liquid interfaces: Reactions and electrochemistry I
O 13.11: Vortrag
Montag, 9. März 2026, 17:30–17:45, TRE/PHYS
In-situ magneto-optical tracking of redox reactions in NiFe electrocatalysts — •Sandhya Chandola1,2, Karuppasamy Dharmaraj2, Jörg Rappich2, and Norbert Esser1 — 1Institut für Festkörperphysik,TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Schwarzschildstr. 8, 12489 Berlin, Germany
Nickel/Iron (NiFe)-based electrocatalysts are known to be efficient catalysts for the oxygen evolution reaction (OER), involved in water splitting. By using a polarization sensitive optical spectroscopy technique, Reflection Anisotropy Spectroscopy (RAS), at near normal incidence, we show how the polarization state of the reflected light can be directly correlated with the oxidation state changes of NiFe catalysts via two entangled magnetic effects, which are the magneto-optical Kerr effect (MOKE) at the surface of the NiFe layer and Faraday rotation within the layer. The polarization state can be used to monitor phase transitions which are not observed in unpolarized absorption spectra.
Increasing amounts of Fe in the NiFe films correspond to greater changes in the RAS/MOKE intensities, up to the solubility limit of ~ 25% Fe, after which the spectra do not show any more changes. RAS/MOKE is shown to be a valuable spectroscopic technique which can probe changes in the redox states for different NiFe ratios, due to the indirect influence of magneto-optical effects with the implied role of ferromagnetic ordering in enhancing catalytic activity.
Keywords: Magneto-Optic; Electrocatalyst; NiFe; OER