Sm1-XSrxMnO3 (X = 0.1, 0.2, 0.3, and 0.4) Perovskite (SSM) with A-Site Doping Optimized as Oxygen Reduction Reaction (ORR) Electrocatalyst

Abstract

A highly selective, stable and efficient non-precious metal catalyst is crucial for alkaline fuel cell applications. Recently, rare earth-based perovskite showed improved oxygen reduction reaction (ORR) which is analogous to commercial Pt/C. In this paper, strontium doped SmMnO₃ (Sm_1-xSr_xMnO₃ (x=0.1, 0.2, 0.3, and 0.4)) are synthesized by sol-gel route. The structure, valence state, and morphology of these samples were analyzed and oxygen adsorption behavior was investigated. Further, using the RRDE electrode (rotating ring disk electrode) the electro-catalytic behavior of the prepared catalyst toward ORR were investigated. The absorption of molecular oxygen by SmMnO₃ catalyst was improved and the Mn valence state was tailored by doping Sr into the crystal lattice of SmMnO₃. Sm_1-xSr_xMnO₃ (x = 0.3) displayed highest ORR activity and stability among the synthesized electrocatalyst, with kinetic current density and onset potentials of 1.15 mA/cm², and 0.92 V, respectively. High stability and electron transfer number around 4 makes the prepared electrocatalyst a viable alternate to commercial Pt/C for alkaline fuel cell application.