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Enlarged CoO Covalency in Octahedral Sites Leading to Highly Efficient Spinel Oxides for Oxygen Evolution Reaction
Author(s) -
Zhou Ye,
Sun Shengnan,
Song Jiajia,
Xi Shibo,
Chen Bo,
Du Yonghua,
Fisher Adrian C.,
Cheng Fangyi,
Wang Xin,
Zhang Hua,
Xu Zhichuan J.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201802912
Subject(s) - spinel , oxygen evolution , electrocatalyst , oxygen , cobalt , oxide , materials science , catalysis , cobalt oxide , inorganic chemistry , chemistry , electrochemistry , metallurgy , electrode , biochemistry , organic chemistry
Cobalt‐containing spinel oxides are promising electrocatalysts for the oxygen evolution reaction (OER) owing to their remarkable activity and durability. However, the activity still needs further improvement and related fundamentals remain untouched. The fact that spinel oxides tend to form cation deficiencies can differentiate their electrocatalysis from other oxide materials, for example, the most studied oxygen‐deficient perovskites. Here, a systematic study of spinel ZnFe x Co 2− x O 4 oxides ( x = 0–2.0) toward the OER is presented and a highly active catalyst superior to benchmark IrO 2 is developed. The distinctive OER activity is found to be dominated by the metal–oxygen covalency and an enlarged CoO covalency by 10–30 at% Fe substitution is responsible for the activity enhancement. While the pH‐dependent OER activity of ZnFe 0.4 Co 1.6 O 4 (the optimal one) indicates decoupled proton–electron transfers during the OER, the involvement of lattice oxygen is not considered as a favorable route because of the downshifted O p‐band center relative to Fermi level governed by the spinel's cation deficient nature.