Details

Autor(en) / Beteiligte

• Morales, Dulce M.
• Kazakova, Mariya A.
• Medina, Danea
• Villalobos, Javier
• Schuck, Götz
• Risch, Marcel
• Schuhmann, Wolfgang

Titel

MnFeNi‐Based Composite as a Case Study of a Bifunctional Oxygen Electrocatalyst under Dynamically Changing Electrode Potentials

Ist Teil von

• ChemCatChem, 2024-05, Vol.16 (9), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• High‐performance bifunctional electrocatalysts for the oxygen reduction (ORR) and oxygen evolution reaction (OER) are essential components in energy conversion and storage technologies. Yet, their poor reversibility hinders their applicability. A highly active ORR/OER catalyst, consisting of multiwalled carbon nanotubes‐supported MnFeNiOx nanoparticles, was subjected to sequences of chronoamperometric steps alternating between the ORR, the OER and highly cathodic potentials (Ec). Rotating ring disk electrode methods revealed that applying Ec leads to a small increase in the current and peroxide species yield during the ORR while enhancing substantially the OER. X‐ray absorption spectroscopy showed irreversible changes in the chemical state of MnFeNiOx correlating with its catalytic properties. The complexity of changes that a composite catalyst may undergo under varying potentials, the importance of monitoring product formation, and the convenience of using dynamic electrochemical sequences for the assessment of catalyst reversibility, as well as for the activation and/or restoration of their catalytic properties, are highlighted. MnFeNiOx is exposed to chronoamperometric sequences involving oxygen reduction (ORR) and oxygen evolution (OER) potentials, as well as highly cathodic pulses Ec. Rotating (ring) disk electrode methods revealed that Ec recovers partially the ORR currents, increases the yield of peroxide species, and enhances substantially the OER activity. These results are correlated to changes in metal valence determined by X‐ray absorption spectroscopy.