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 Pt50Au50/C toward oxygen reduction reaction has been promoted by the manipulation of their surface condition through CeO2 addition and N-2 heat treatment synergistically. Pt50Au50/C with CeO2 additions (PtAuCe) were prepared by the DP process and then further treated at 520-620 K under N-2. 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