Thermodynamic Stability and Intrinsic Activity of La_1−xSr_xMnO₃ (LSM) as an Efficient Bifunctional OER/ORR Electrocatalysts: A Theoretical Study

Abstract

Perovskite oxides, being transition metal oxides, show promise as bifunctional catalysts being able to catalyze both oxygen evolution reactions (OER) and oxygen reduction reactions (ORR). These two reactions play a crucial role in energy storage and energy conversion devices. An important feature of perovskite catalyst is their ability to be tuned, as tuning can positively affect both reactivity and stability. In this study, Density Functional Theory (DFT) has been utilized to calculate both the equilibrium phase stability and the overpotentials (reactivity performance indicator of the catalysts) of La1−xSrxMnO3 (LSM) structures with different stoichiometry by introducing Mn and O vacancies for both the OER/ORR reactions. The electronic structures reveal that combined Mn and O vacancies can lead to higher catalytic activity for both OER and ORR due to the optimum filling of antibonding orbital electrons. Moreover, both O p-band centers and equilibrium phase stability plots show that LSM structures can be stable at normal OER/ORR operating conditions in an alkali medium.

Keywords

• bifunctional
• electrocatalyst
• OER/ORR
• DFT
• overpotentials
• stability