(513bd) Ab Initio Study of Vacancy Formation in La1-XSrxMnO3 (LSM) and Its Effect on Thermodynamic Stability and Intrinsic Activity As Bi-Functional Oer/ORR Catalyst

We used density functional theory calculations to study the efficient bi-functional i.e. oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electro-catalyst, which is vital to the new generation of electrochemical energy storage and conversion devices such as metal-air batteries and Fuel cells. This work selects La_1-xSr_xMnO₃ (LSM) perovskite oxides as a model system because of their low-cost and high versatility in compositions and tunable electronic structures. The vacancy formation energies show that both O and Mn vacancy can be created via different pathways to achieve the desired LSM structures at different experimental conditions such as O-rich and O-poor environments. The electrochemical reactivity of the various vacancies can be correlated to the fundamental electronic properties. Our calculations predict that some of the vacancies have the potential for higher intrinsic activity than pristine LSM, a fact confirmed by previous experimental results.

Acknowledgements: Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund (ACS-PRF, 58740-UR6) for support of this research. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562, TACC at the stampede2 through allocation [TG-DMR140131]. Use of the Center for Nanoscale Materials was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.