Phase change of bimetallic PdCo electrocatalysts caused by different heat-treatment temperatures: Effect on oxygen reduction reaction activity

► Importance of controlling the heat-treatment temperature determining the fine structure (core-shell structure or alloy-phase structure) of PdCo bimetallic electrocatalysts. ► To date, there was little attention on the heat-treatment temperature in the preparation process of PdCo electrocatalysts. ► Recently, with synchrotron studies like EXAFS and HRPD, we have found that the drastic change in fine structure of PdCo occurred by different heat-treatment condition. ► Such change affected the ORR activity considerably.