Well‐Defined PtCo@Pt Core‐Shell Nanodendrite Electrocatalyst for Highly Durable Oxygen Reduction Reaction

The rational design of efficient electrocatalysts with controllable structure and composition is crucial for enhancing the lifetime and cost-effectiveness of oxygen reduction reaction (ORR). PtCo nanocrystals have gained attention due to their exceptional activity, yet suffer from stability issues in acidic media. Herein, an active and highly stable electrocatalyst is developed, namely 3D Pt₇Co₃@Pt core-shell nanodendrites (NDs), which are formed through the self-assembly of small Pt nanoparticles (≈6 nm). This unique structure significantly improves the ORR with an enhanced mass activity (MA) of 0.54 A mg_Pt ^-1, surpassing that of the commercial Pt/C (com-Pt/C) catalyst by three fold (0.17 A mg_Pt ^-1). The well-organized dendritic morphology, along with the Pt-rich shell, contributes significantly to the observed high catalytic activity and superior stability for acidic ORR, which exhibit a loss of 2.1% in MA and, impressively, an increase of 12.0% in specific activity (SA) after an accelerated durability test (ADT) of 40,000 potential-scanning cycles. This work offers insights for improving the design of highly stable Pt-based electrocatalysts for acidic ORR.