Stimulation of Electro-oxidation Catalysis by Bulk-Structural Transformation in Intermetallic ZrPt3 Nanoparticles

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• 作者：Gubbala V. Ramesh ; Rajesh Kodiyath ; Toyokazu Tanabe ; Maidhily Manikandan ; Takeshi Fujita ; Naoto Umezawa ; Shigenori Ueda ; Shinsuke Ishihara ; Katsuhiko Ariga ; Hideki Abe
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：September 24, 2014
• 年：2014
• 卷：6
• 期：18
• 页码：16124-16130
• 全文大小：476K
• ISSN：1944-8252

文摘

Although compositional tuning of metal nanoparticles (NPs) has been extensively investigated, possible control of the catalytic performance through bulk-structure tuning is surprisingly overlooked. Here we report that the bulk structure of intermetallic ZrPt₃ NPs can be engineered by controlled annealing and their catalytic performance is significantly enhanced as the result of bulk-structural transformation. Chemical reduction of organometallic precursors yielded the desired ZrPt₃ NPs with a cubic FCC-type structure (c-ZrPt₃ NPs). The c-ZrPt₃ NPs were then transformed to a different phase of ZrPt₃ with a hexagonal structure (h-ZrPt₃ NPs) by annealing at temperatures between 900 and 1000 掳C. The h-ZrPt₃ NPs exhibited higher catalytic activity and long-term stability than either the c-ZrPt₃ NPs or commercial Pt/C NPs toward the electro-oxidation of ethanol. Theoretical calculations have elucidated that the enhanced activity of the h-ZrPt₃ NPs is attributed to the increased surface energy, whereas the stability of the catalyst is retained by the lowered bulk-free-energy.

Keywords:

catalysts; intermetallic compounds; bulk structural transformation; surface energy; polymer membrane electrolyte fuel cells