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 leading to increased 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.
Kelsey A
KA
Stoerzinger
‡Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.|§Department of Physics, Sungkyunkwan University, Suwon 440-746, South Korea.
Woo Seok
WS
Choi
‡Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.|∥Department of Physics, Pusan National University, Busan 609735, South Korea.
Hyoungjeen
H
Jeen
‡Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Ho Nyung
HN
Lee
⊥Mechanical Engineering Department, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Yang
Y
Shao-Horn
alkaline; electronic structure; oxygen reduction; perovskite; thin films; water splitting