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Title: Role of strain and conductivity in oxygen electrocatalysis on LaCoO3 thin films

The slow kinetics of the oxygen reduction and evolution reactions (ORR, OER) hinder energy conversion and storage in alkaline fuel cells and electrolyzers employing abundant transition metal oxide catalysts. Systematic studies linking material properties to catalytic activity are lacking, in part due to the heterogeneous nature of powder-based electrodes. We demonstrate, for the first time, that epitaxial strain can tune the activity of oxygen electrocatalysis in alkaline solutions, focusing on the model chemistry of LaCoO3, where moderate tensile strain can further induce changes in the electronic structure via spin state to increase activity. The resultant decrease in charge transfer resistance to the electrolyte reduces the overpotential in the ORR more notably than the OER and suggests a different dependence of the respective rate-limiting steps on electron transfer. This provides new insight into the reaction mechanism applicable to a range of perovskite chemistries, key to the rational design of highly active catalysts.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1185843
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 6; Journal Issue: 3; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY thin films; perovskite; electronic structure; oxygen reduction; water splitting; alkaline