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Title: In Situ X-ray Absorption Spectroscopy of a Synergistic Co–Mn Oxide Catalyst for the Oxygen Reduction Reaction

Abstract

Identifying the catalytically active site(s) in the oxygen reduction reaction (ORR), under real-time electrochemical conditions, is critical to the development of fuel cells and other technologies. We have employed in situ synchrotron-based X-ray absorption spectroscopy (XAS) to investigate the synergistic interaction of a Co−Mn oxide catalyst which exhibits impressive ORR activity in alkaline fuel cells. X-ray absorption near edge structure (XANES) was used to track the dynamic structural changes of Co and Mn under both steady state (constant applied potential) and nonsteady state (potentiodynamic cyclic voltammetry, CV). Under steady state conditions, both Mn and Co valences decreased at lower potentials, indicating the conversion from Mn-(III,IV) and Co(III) to Mn(II,III) and Co(II), respec-tively. Rapid X-ray data acquisition, combined with a slow sweep rate in CV, enabled a 3 mV resolution in the applied potential, approaching a nonsteady (potentiody-namic) state. Changes in the Co and Mn valence states were simultaneous and exhibited periodic patterns that tracked the cyclic potential sweeps. To the best of our knowledge, this represents the first study, using in situ XAS, to resolve the synergistic catalytic mechanism of a bimetallic oxide. Strategies developed/described herein can provide a promising approach to unveil the reaction mechanism for other multimetallic electrocatalysts.

Authors:
ORCiD logo [1];  [2];  [1];  [3];  [1];  [4];  [1];  [1]; ORCiD logo [1]; ORCiD logo [2];  [3]; ORCiD logo [2]; ORCiD logo [1]
  1. Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
  2. College of Chemistry and Molecular Sciences, Hubei Key Lab of Electrochemical Power Sources, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
  3. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
  4. Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Alkaline-Based Energy+B11:C29 Solutions (CABES); Cornell Univ., Ithaca, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1566594
DOE Contract Number:  
SC0019445
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 141; Journal Issue: 4; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), electrocatalysis, hydrogen and fuel cells, charge transport, membranes, water, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Yang, Yao, Wang, Ying, Xiong, Yin, Huang, Xin, Shen, Luxi, Huang, Rong, Wang, Hongsen, Pastore, James P., Yu, Seung-Ho, Xiao, Li, Brock, Joel D., Zhuang, Lin, and Abruña, Héctor D. In Situ X-ray Absorption Spectroscopy of a Synergistic Co–Mn Oxide Catalyst for the Oxygen Reduction Reaction. United States: N. p., 2018. Web. doi:10.1021/jacs.8b12243.
Yang, Yao, Wang, Ying, Xiong, Yin, Huang, Xin, Shen, Luxi, Huang, Rong, Wang, Hongsen, Pastore, James P., Yu, Seung-Ho, Xiao, Li, Brock, Joel D., Zhuang, Lin, & Abruña, Héctor D. In Situ X-ray Absorption Spectroscopy of a Synergistic Co–Mn Oxide Catalyst for the Oxygen Reduction Reaction. United States. doi:10.1021/jacs.8b12243.
Yang, Yao, Wang, Ying, Xiong, Yin, Huang, Xin, Shen, Luxi, Huang, Rong, Wang, Hongsen, Pastore, James P., Yu, Seung-Ho, Xiao, Li, Brock, Joel D., Zhuang, Lin, and Abruña, Héctor D. Thu . "In Situ X-ray Absorption Spectroscopy of a Synergistic Co–Mn Oxide Catalyst for the Oxygen Reduction Reaction". United States. doi:10.1021/jacs.8b12243.
@article{osti_1566594,
title = {In Situ X-ray Absorption Spectroscopy of a Synergistic Co–Mn Oxide Catalyst for the Oxygen Reduction Reaction},
author = {Yang, Yao and Wang, Ying and Xiong, Yin and Huang, Xin and Shen, Luxi and Huang, Rong and Wang, Hongsen and Pastore, James P. and Yu, Seung-Ho and Xiao, Li and Brock, Joel D. and Zhuang, Lin and Abruña, Héctor D.},
abstractNote = {Identifying the catalytically active site(s) in the oxygen reduction reaction (ORR), under real-time electrochemical conditions, is critical to the development of fuel cells and other technologies. We have employed in situ synchrotron-based X-ray absorption spectroscopy (XAS) to investigate the synergistic interaction of a Co−Mn oxide catalyst which exhibits impressive ORR activity in alkaline fuel cells. X-ray absorption near edge structure (XANES) was used to track the dynamic structural changes of Co and Mn under both steady state (constant applied potential) and nonsteady state (potentiodynamic cyclic voltammetry, CV). Under steady state conditions, both Mn and Co valences decreased at lower potentials, indicating the conversion from Mn-(III,IV) and Co(III) to Mn(II,III) and Co(II), respec-tively. Rapid X-ray data acquisition, combined with a slow sweep rate in CV, enabled a 3 mV resolution in the applied potential, approaching a nonsteady (potentiody-namic) state. Changes in the Co and Mn valence states were simultaneous and exhibited periodic patterns that tracked the cyclic potential sweeps. To the best of our knowledge, this represents the first study, using in situ XAS, to resolve the synergistic catalytic mechanism of a bimetallic oxide. Strategies developed/described herein can provide a promising approach to unveil the reaction mechanism for other multimetallic electrocatalysts.},
doi = {10.1021/jacs.8b12243},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 4,
volume = 141,
place = {United States},
year = {2018},
month = {12}
}