Superior Bifunctional Electrocatalytic Activity of Ba0.5Sr0.5Co0.8Fe0.2O3-δ/ Carbon Composite Electrodes: Insight into the Local Electronic Structure

Carbon acts as an activity booster for Ba0.5Sr0.5Co0.8Fe0.2O3-δ for the oxygen reduction and evolution reactions due to the occurrence of electronic effects that change the local perovskite electronic configuration. The change of the Co oxidation state in Ba0.5Sr0.5Co0.8Fe0.2O3-δ when it is coupled with carbon can account for the superior catalytic activity of composite electrodes compared to single material electrodes.