Efficient bifunctional catalytic activity of nanoscopic Pd-decorated La0.6Sr0.4CoO3-δ perovskite toward Li-O2 battery, oxygen reduction, and oxygen evolution reactions

Palladium decoration is performed on La0.6Sr0.4CoO3-delta (LSC) with different loadings (5 to 30 wt.%) to improve its oxygen reduction reaction (ORR) activity without sacrificing its oxygen evolution reaction (OER) capability. The Pd decoration yields a higher specific surface area as loading concentration increases and leads to the formation of more porous active sites for efficient activity. Both aqueous and organic media are used to study the electrocatalytic activity of the prepared Pd-LSC composite. In aqueous media, the Pd-LSC materials exhibit higher ORR and OER activities than native LSC and RuO2. For example, as Pd loading increases in aqueous media (5 < 10 < 20 < 30 wt.%), the performance improves and becomes comparable to the that of a conventional Pt/C catalyst, whereas 20 wt.% loading establishes better OER activity. This interesting result in aqueous media logically alerts us to study the electrocatalytic activity in organic medium toward Li-O-2 battery application. Similar to the aqueous media, the Pd-LSC composite outperformed the native materials, like LSC and ketjen black. More specifically, 30 wt.% loading delivers the highest discharge capacity and longest cycle life compared to the other compositions. Postmortem studies are also performed to ensure the electrocatalytic activity of the Pd-LSC composite. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.