Abstract
In this work, we report a systematic study on temperature-dependent local structural evolution, oxygen stoichiometry, and electrochemical properties of an oxygen-deficient perovskite Sr0.7Y0.3CoO3-δ (SYC30) for oxygen electrocatalysis. The obtained results are then closely compared with its analogue Sr0.9Y0.1CoO3-δ (SYC10) of different crystal structures to establish structure-activity relationships. The comparison shows that both SYC30 and SYC10 consist of alternate layers of oxygen-deficient Co1-polyhedra and oxygen-saturated Co2-octahedra with Co1-polyhedra being responsible for Vo•• migration. It is also found that the distribution and concentration of oxygen vacancies within the Co1-layer are, respectively, less symmetrical and lower in SYC30 than those in SYC10, making the former unfavorable for oxygen transport. A molecular orbital energy analysis reveals that the energy gap between Fermi level and O 2p level in the active Co1-polyhedra is larger in SYC30 than that in SYC10, further suggesting that SYC10 is a better oxide-ion conductor and thus a better electrocatalyst for oxygen reduction reaction, which is unambiguously confirmed by the subsequent electrochemical measurements.
Original language | English |
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Pages (from-to) | 35984-35993 |
Number of pages | 10 |
Journal | ACS Applied Materials and Interfaces |
Volume | 10 |
Issue number | 42 |
DOIs | |
State | Published - Oct 24 2018 |
Funding
This work was funded by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under award number DE-AR0000492 and Office of Fossil Energy, U.S. Department of Energy, under award number DE-FE-0023317, and National Science Foundation, under award number of CBET-1464112. Neutron scattering was carried out at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, which is one of the user facilities sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The authors thank M. J. This work was funded by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under award number DE-AR0000492 and Office of Fossil Energy, U.S. Department of Energy, under award number DE-FE-0023317, and National Science Foundation, under award number of CBET-1464112. Neutron scattering was carried out at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, which is one of the user facilities sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.
Keywords
- neutron diffraction
- oxygen electrocatalyst
- oxygen migration
- perovskite
- solid oxide fuel cell