Electrochemical Properties of Low Bi Doped La0.60Dy0.10Sr0.30Mn(1-x)BixO3 Perovskite Magneticaloric Materials

Abstract

Developing low-cost, high-durability and high-performance electrocatalytic materials are needed for hydrogen/oxygen evolution (HER/OER) and oxygen reduction reactions (ORR) which are crucial steps for regenerative fuel cells. Although Pt-based, RuO2 and IrO2 materials are widely used for these purposes, other alternative materials are required with desired properties. In this regard, we studied the electrochemical properties of lanthanum-based perovskites which were synthesized by sol-gel method. We investigated the addition of 10% Dy and 30% Sr into the A site and a small amount of Bi (x: 0, 0.03 and 0.1) added into the B site of La0.60Dy0.10Sr0.30Mn(1-x)BixO3 perovskites on HER, OER and ORR in 1 M KOH alkaline media at room temperature. While the addition of 0% and 3% Bi exhibited poor HER activities, the effect of 10% Bi in the structure enhanced HER activities by lowering onset potential from -1.389 V to -1.036 V (vs. Ag/AgCl) and increasing specific current density at -1.4 V from -13.3 mA cm-2 to -121.8 mA cm-2. Similarly, OER activity was also improved due to 10% Bi and onset potential and specific current density was found to be 0.758 V and 88.3 mA cm-2, respectively. The large Tafel slopes indicate that the ORR mechanism is possible in the structure but at a slow rate. The addition of 10% Bi in the structure resulted in a very high resistance of 19.3 kΩ and it reduced to a desired value of 3.5 kΩ due to ion conducting paths developed in the catalysts.