Stabilization and compressive strain effect of AuCu core on Pt shell for oxygen reduction reaction

A great challenge in fuel cell development involves improving the durability and electrocatalytic activity of Pt-based electrocatalysts, while reducing the Pt loading. Herein, we report for the first time the synthesis of core-shell AuCu@Pt nanoparticles, which exhibit superior electrocatalytic activity and excellent stability towards oxygen reduction reaction (ORR). The Au component in the AuCu alloy core is crucial toward stabilizing the Pt shell during ORR. The extraordinary electrocatalytic activity of the AuCu@Pt nanoparticles for ORR is attributed to the compressive strain effect exerted by the AuCu alloy core on the Pt shell, which is induced by the slightly smaller lattice parameter of the AuCu core. In contrast, pure Au core with a larger lattice parameter than Pt would induce a tensile strain effect on the Pt shell, decreasing the electrocatalytic activity of Pt for ORR. This study illustrates that tuning the surface strain in Pt-based nanomaterials can be an effective way to manipulate the specific electrocatalytic activity. Moreover, the replacement of precious Pt core with the less expensive AuCu alloy can significantly reduce Pt loading and the associated catalyst cost, while achieving a superior electrocatalytic activity.