Reversible Surface Segregation of Pt in a Pt3Au/C Catalyst and Its Effect on the Oxygen Reduction Reaction

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• 作者：Kug-Seung Lee ; Hee-Young Park ; Hyung Chul Ham ; Sung Jong Yoo ; Hyoung Juhn Kim ; EunAe Cho ; Arumugam Manthiram ; Jong Hyun Jang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：May 9, 2013
• 年：2013
• 卷：117
• 期：18
• 页码：9164-9170
• 全文大小：393K
• 年卷期：v.117,no.18(May 9, 2013)
• ISSN：1932-7455

文摘

Reversible surface segregation of Pt in Pt₃Au/C catalysts was accomplished through a heat treatment under a CO or Ar atmosphere, which resulted in surface Pt segregation and reversed segregation, respectively. The Pt-segregated Pt₃Au/C exhibited a significantly improved oxygen reduction reaction (ORR) activity (227 mA/mg_metal) compared to that of commercial Pt/C (59 mA/mg_metal). For the Pt-segregated Pt₃Au/C, the increased OH-repulsive properties were validated by a CO bulk oxidation analysis and also by density functional theory (DFT) calculations. Interestingly, the DFT calculations revealed that the binding energy for Pt-segregated Pt₃Au (111) surfaces was 0.1 eV lower than that for Pt (111) surfaces, which has been previously reported to exhibit the optimum OH binding energy for the ORR. Therefore, the reversible surface segregation is expected to provide a practical way to control the surface states of Pt鈥揂u bimetallic catalysts to enhance ORR activity. In addition, the Pt-segregated Pt₃Au/C showed excellent electrochemical stability, as evidenced by its high-performance retention (96.4%) after 10鈥?00 potential cycles, in comparison to that of Pt/C (55.3%).