Local coordination and ordering engineering to design efficient core-shell oxygen reduction catalysts

For most core–shell nanostructured Pt-based alloy electrocatalysts, the local environment and configuration of surface Pt layers are randomly generated, which would hinder the further improvement of the utilization, activity and stability of Pt atoms. Herein, we have selected AuCu alloys with different structural ordering as substrates and deposited a Pt shell on their surface via the precise control of replacing Cu with Pt atoms. Various physical and electrochemical characterizations indicate that the structural ordering of an AuCu core could influence the distribution of surface Pt atoms due to the rearrangement of surface atoms. After optimization, the obtained catalysts displayed a high mass activity (0.75 A·mg_Pt⁻¹) and specific activity (0.491 mA·cm_Pt⁻²) for the oxygen reduction reaction (ORR), which were nearly 7.5 times and 3.6 times those of commercial Pt/C, respectively. In addition, the catalysts could also exhibit a high stability with a negligible activity decay after 10,000 cycles of accelerated durability tests (ADTs). The density functional theory (DFT) calculation reveals that the precisely controlled Pt local environment could lower the Gibbs free energy barrier for the rate-determining step of ORR more than a random distribution could, thus enhancing the catalytic performance of the prepared catalysts. © 2020 Electrochemical Society Inc.. All rights reserved.