Surface condition manipulation and oxygen reduction enhancement of PtAu/C catalysts synergistically modified by CeO₂ addition and N₂ treatment

In this study, the electrochemical activity of Pt₅₀Au ₅₀/C toward oxygen reduction reaction has been promoted by the manipulation of their surface condition through CeO₂ addition and N₂ heat treatment synergistically. Pt₅₀Au₅₀/C with CeO₂ additions (PtAuCe) were prepared by the DP process and then further treated at 520-620 K under N₂. The surface segregation profile of the PtAuCe alloys and surface-activity correlation has been elucidated systematically by use of the surface analysis and electrochemical characterization. It is observed that the inherent surface segregation of Au of Pt-Au systems at high temperatures based on the thermodynamic models has been changed due to the CeO₂ modification, and accordingly in the PtAuCe catalysts, CeO₂-induced Pt surface segregation and surface reconstruction takes place. As a result, the variations in surface compositions affect the ORR activity of the Pt-Au catalysts, and the enhancement of Pt or Au surface composition causes the promotion or deterioration in ORR activity for various heat-treated catalysts, respectively