Lanthanide based double perovskites: Bifunctional catalysts for oxygen evolution/reduction reactions

In this work, we are reporting the facile synthesis of double perovskite oxide materials LnBa0_.5Sr_0·5Co_1·5Fe_0·5O₆ (LnBSCF, Ln = Pr, Nd, Sm, and Gd) using citrate-nitrate based sol-gel method. These double perovskite oxide materials exhibit bifunctional catalytic activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The phase formation and structure of the prepared oxides have been determined by powder X-ray diffraction, SEM analysis. Presence of various phases is analyzed and quantified by mean of Le-Bail refinement of XRD profiles. SEM analyses confirm the morphology and composition of prepared catalysts. Electrochemical measurements, e.g. Linear Sweep Voltammetry, Cyclic Voltammetry and Electrochemical Impedance spectroscopy were used to study catalytic performance of prepared catalyst towards both oxygen evolution and oxidation reduction reactions in alkaline solution. Better catalytic performance was obtained in case of double perovskites as compared to parent perovskite for both reactions. Best catalytic performance was observed for Gd based double perovskite.