Bismuth Substituted Strontium Cobalt Perovskites for Catalyzing Oxygen Evolution

In this study, we employ the strategy of substitution with more electronegative/acidic A-site ions in the cobalt perovskites to alter O 2p-band center, surface hydroxide affinity, and oxygen evolution reaction (OER) activity and stability in the basic electrolyte. Galvanostatically charged Bi_0.2Sr_0.8CoO_3-δ (δ close to zero) was shown to exhibit record OER specific activity exceeding not only La_xSr_1-xCoO_3-δ but also charged SrCoO_3-δ (δ close to zero), one of the most active oxide OER catalysts reported so far. The enhanced OER activity of charged Bi_0.2Sr_0.8CoO_3-δ can be attributed to greater hydroxide affinity facilitating the deprotonation of surface bound intermediates due to the presence of strong Lewis acidic A-site Bi³⁺ ions, while the high stability can result from lowered O 2p-band center relative to the Fermi level. This work provides a novel example in the rational design of highly active oxide catalysts for OER by leveraging the inductive effect.