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Self‐Assembly of Spinel Nanocrystals into Mesoporous Spheres as Bifunctionally Active Oxygen Reduction and Evolution Electrocatalysts
Author(s) -
Lee Dong Un,
Li Jingde,
Park Moon Gyu,
Seo Min Ho,
Ahn Wook,
Stadelmann Ian,
RicardezSandoval Luis,
Chen Zhongwei
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201700369
Subject(s) - oxygen evolution , spinel , nanocrystal , mesoporous material , oxygen , electrochemistry , electrocatalyst , chemistry , oxide , inorganic chemistry , chemical engineering , catalysis , materials science , electrode , nanotechnology , organic chemistry , engineering , metallurgy
The present work introduces spinel oxide nanocrystals self‐assembled into mesoporous spheres that are bifunctionally active towards catalyzing both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The electrochemical evaluation reveals that (Ni,Co) 3 O 4 demonstrates a significantly positive‐shifted ORR onset and half‐wave potentials [−0.127 and −0.292 V vs. saturated calomel electrode (SCE), respectively], whereas Co 3 O 4 results in a negative‐shifted OER potential (0.65 V vs. SCE) measured at 10 mA cm −2 . Based on the DFT analysis, the potential at which all oxygen intermediate reactions proceed spontaneously is the highest for (Ni,Co) 3 O 4 ( U =0.66 eV) during ORR, whereas it is the lowest for Co 3 O 4 ( U =2.09 eV) during OER. The high ORR activity of (Ni,Co) 3 O 4 is attributed to the enhanced electrical conductivity of the spinel lattice, and the high OER activity of Co 3 O 4 is attributed to relatively weak adsorption energy promoting rapid release of evolved oxygen.