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The Roles of Composition and Mesostructure of Cobalt‐Based Spinel Catalysts in Oxygen Evolution Reactions
Author(s) -
Rabe Anna,
Büker Julia,
Salamon Soma,
Koul Adarsh,
Hagemann Ulrich,
Landers Joachim,
Friedel Ortega Klaus,
Peng Baoxiang,
Muhler Martin,
Wende Heiko,
Schuhmann Wolfgang,
Behrens Malte
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202102400
Subject(s) - spinel , cobalt , catalysis , oxygen evolution , oxygen , composition (language) , chemical engineering , materials science , chemistry , metallurgy , organic chemistry , engineering , electrode , electrochemistry , linguistics , philosophy
By using the crystalline precursor decomposition approach and direct co‐precipitation the composition and mesostructure of cobalt‐based spinels can be controlled. A systematic substitution of cobalt with redox‐active iron and redox‐inactive magnesium and aluminum in a cobalt spinel with anisotropic particle morphology with a preferred 111 surface termination is presented, resulting in a substitution series including Co 3 O 4 , MgCo 2 O 4 , Co 2 FeO 4 , Co 2 AlO 4 and CoFe 2 O 4 . The role of redox pairs in the spinels is investigated in chemical water oxidation by using ceric ammonium nitrate (CAN test), electrochemical oxygen evolution reaction (OER) and H 2 O 2 decomposition. Studying the effect of dominant surface termination, isotropic Co 3 O 4 and CoFe 2 O 4 catalysts with more or less spherical particles are compared to their anisotropic analogues. For CAN‐test and OER, Co 3+ plays the major role for high activity. In H 2 O 2 decomposition, Co 2+ reveals itself to be of major importance. Redox active cations in the structure enhance the catalytic activity in all reactions. A benefit of a predominant 111 surface termination depends on the cobalt oxidation state in the as‐prepared catalysts and the investigated reaction.