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Evidence of Mars‐Van‐Krevelen Mechanism in the Electrochemical Oxygen Evolution on Ni‐Based Catalysts
Author(s) -
Ferreira de Araújo Jorge,
Dionigi Fabio,
Merzdorf Thomas,
Oh HyungSuk,
Strasser Peter
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202101698
Subject(s) - oxygen evolution , catalysis , electrochemistry , redox , oxygen , chemistry , inorganic chemistry , electrolyte , hydroxide , reaction mechanism , organic chemistry , electrode
Water oxidation is a crucial reaction for renewable energy conversion and storage. Among the alkaline oxygen evolution reaction (OER) catalysts, NiFe based oxyhydroxides show the highest catalytic activity. However, the details of their OER mechanism are still unclear, due to the elusive nature of the OER intermediates. Here, using a novel differential electrochemical mass spectrometry (DEMS) cell interface, we performed isotope‐labelling experiments in 18 O‐labelled aqueous alkaline electrolyte on Ni(OH) 2 and NiFe layered double hydroxide nanocatalysts. Our experiments confirm the occurrence of Mars‐van‐Krevelen lattice oxygen evolution reaction mechanism in both catalysts to various degrees, which involves the coupling of oxygen atoms from the catalyst and the electrolyte. The quantitative charge analysis suggests that the participating lattice oxygen atoms belong exclusively to the catalyst surface, confirming DFT computational hypotheses. Also, DEMS data suggest a fundamental correlation between the magnitude of the lattice oxygen mechanism and the faradaic efficiency of oxygen controlled by pseudocapacitive oxidative metal redox charges.