skip to main content

DOE PAGESDOE PAGES

Title: The Influence of Fe Substitution in Lanthanum Calcium Cobalt Oxide on the Oxygen Evolution Reaction in Alkaline Media

The effect due to systematic substitution of cobalt by iron in La0.6Ca0.4Co1-xFexO3 towards the oxygen evolution reaction(OER) in alkaline media has been investigated. We synthesized these compounds by a facile glycine-nitrate synthesis and the phase formation was confirmed by X-ray diffraction and Neutron Diffraction elemental analysis. The apparent OER activity was evaluated by quasi steady state current measurements in alkaline media using a traditional three-electrode cell. X-ray photoelectron spectroscopy shows iron substitution causes an increase in the surface concentration of various cobalt oxidation states. Tafel slope in the vicinity of 60 mV/decade and electrochemical reaction order towards OH- near unity were achieved for the unsubstituted La0.6Ca0.4CoO3. Moreover, a decrease in the Tafel slope to 49 mV/decade was observed when iron is substituted in high amounts in the perovskite structure. The area specific current density showed dependence on the Fe fraction, however the relationship of specific current density with Fe fraction is not linear. High Fe substitutions, La0.6Ca0.4Co0.2Fe0.8O3 and La0.6Ca0.4Co0.1Fe0.9O3 showed higher area specific activity towards OER than La0.6Ca0.4CoO3 or La0.6Ca0.4FeO3. Finally, we believe iron inclusion in the cobalt sites of the perovskite helps decrease the electron transfer barrier and facilitates the formation of cobalt-hydroxide at the surface. Possible OER mechanismsmore » based on the observed kinetic parameters will be discussed.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5]
  1. Univ. of Rochester, NY (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Soutehrn California, Los Angeles, CA (United States)
  4. Univ. of Yamanashi, Kofu (Japan)
  5. West Virginia Univ., Morgantown, WV (United States)
Publication Date:
OSTI Identifier:
1286965
Grant/Contract Number:
AC05-00OR22725; DGE-0966089
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 163; Journal Issue: 9; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY electrocatalyst; oxygen evolution; transition metal perovskites; water electrolytes