2017/10/31 by Dongkyu Lee, Ryan Jacobs, Youngseok Jee +8 · 51 citations
Chemistry · Materials Science · Mathematics · Physics and Astronomy · #Advancements in Solid Oxide Fuel Cells #Analytical Chemistry (journal) #Catalytic Processes in Materials Science #Chemistry #Crystallography #Electronic and Structural Properties of Oxides #Epitaxy #Materials science #Mathematics #Mineralogy #Nanotechnology #Oxygen #Reduction (mathematics) #cond-mat.mtrl-sci
paper · pdf · doi:10.1021/acs.jpcc.7b06374
published in The Journal of Physical Chemistry C 121(46), 25651-25658 (American Chemical Society)
openalex publication_date 2017/10/31 · openalex created_date 2017/11/10 · arxiv created 2017/12/15 · arxiv updated 2017/12/19 · openalex updated_date 2026/08/06
The slow kinetics of the oxygen reduction reaction (ORR) is one of the key challenges in developing high performance energy devices, such as solid oxide fuel cells. Straining a film by growing on a lattice-mismatched substrate has been a conventional approach to enhance the ORR activity. However, due to the limited choice of electrolyte substrates to alter the degree of strain, a systematic study in various materials has been a challenge. Here, we explore the strain modulation of the ORR kinetics by growing epitaxial La 0.6 Sr 0.4 CoO 3−δ (LSCO) films on yttria-stabilized zirconia substrates with the film thickness below and above the critical thickness for strain relaxation. Two orders of magnitude higher ORR kinetics is achieved in an ultrathin film with ∼0.8% tensile strain as compared to unstrained films. Time-of-flight secondary ion mass spectrometry depth profiling confirms that the Sr surface segregation is not responsible for the enhanced ORR in strained films. We attribute this enhancement of ORR kinetics to the increase in oxygen vacancy concentration in the tensile-strained LSCO film owing to the reduced activation barrier for oxygen surface exchange kinetics. Density functional theory calculations reveal an upshift of the oxygen 2p-band center relative to the Fermi level by tensile strain, indicating the origin of the enhanced ORR kinetics.