Valence Change Ability and Geometrical Occupation of Substitution

Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe2O4 (X = Mn, Co, Ni, Fe...
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Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe2O4 (X = Mn, Co, Ni, Fe) Chao Wei, Zhenxing Feng, Murat Baisariyev, Linghui Yu, Li Zeng, Tianpin Wu, Haiyan Zhao, Yaqin Huang, Michael J. Bedzyk, Thirumany Sritharan, and Zhichuan J. Xu Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.6b00713 • Publication Date (Web): 13 Jun 2016 Downloaded from http://pubs.acs.org on June 14, 2016

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Chemistry of Materials

Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe2O4 (X = Mn, Co, Ni, Fe) Chao Wei,†,⊥ Zhenxing Feng, ‡,⊥, Murat Baisariyev,† Linghui Yu,† Li Zeng,¶ Tianpin Wu,§ Haiyan Zhao,ǁ Yaqin Huang,Δ Michael J. Bedzyk,¶,# Thirumany Sritharan,† Zhichuan J. Xu†,* †

School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore; ‡

School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon, 97331, United States; ¶

Graduate Program of Applied Physics, Northwestern University, Evanston, Illinois, 60208, United States;

#

Materials Science and Engineering, Northwestern University, Evanston, Illinois, 60208, United States;

§

X-ray Science Divisions, Argonne National Laboratory, Lemont, Illinois, 60439, United States;

ǁ

Chemical and Materials Engineering Department, University of Idaho, Idaho Falls, Idaho, 83401, United States;

Δ

College of Materials Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, P.R. China. Supporting Information Placeholder

In recent years, spinel ferrites have attracted much attention as a merging material for oxygen reduction reaction 1 2-3 4(ORR), advanced battery electrodes, and supercapacitors. 5 Generally, the spinel structure can be described by a formu    la Xλ Bλ X λ B2-λ O , where λ is the inversion degree in-between 0 and 1, and superscripts T and O denote the tetrahedral and octahedral sites, respectively. Depending on the cation distribution, a spinel can be normal (λ=0, 100% X in tetrahedral sites), inverse (λ=1, 100% X in octahedral sites), or partially inverse (0