Surface Au Doping Enhances Activity and Stability of PtCo Alloy for Oxygen Reduction Reaction: Insights from In Situ Characterization

Pt-transition metal alloys exhibit high oxygen reduction reaction (ORR) activity but suffer from instability due to non-noble metal leaching and the unclear role of doping sites. Herein, we synthesized PtCo alloy with site-specific Au doping, including surface-doped (PtCo-Au_sur ) and bulk-doped (PtCoAu alloy), to investigate the effects of Au incorporation. In situ synchrotron radiation characterization and electrochemical measurements reveal that surface Au doping could effectively tailor the Pt electronic structure by lowering the d-band center and promoting OH intermediate transition, while a robust Au-Pt shell effectively mitigates Co leaching. Consequently, PtCo-Au sur achieves a mass activity of 0.98 A mg Pt -1 at 0.9 V with 75% retention after 100,000 cyclic voltammetry cycles, and in fuel cells delivers peak power density of 3.1 W cm^-2 under H₂-O₂ conditions and 1.75 W cm^-2 under H₂-Air conditions. This study establishes surface Au doping as an effective strategy for designing durable, high-performance Pt-based fuel cell catalysts.