title: Stimulation of electro-oxidation catalysis by bulk-structural transformation in intermetallic ZrPt₃ nanoparticles.
abstract: 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 °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.
authors.affiliation: National Institute for Materials Science , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Gubbala V
authors.initials: GV
authors.lastname: Ramesh
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kodiyath
authors.forename: Toyokazu
authors.initials: T
authors.lastname: Tanabe
authors.forename: Maidhily
authors.initials: M
authors.lastname: Manikandan
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujita
authors.forename: Naoto
authors.initials: N
authors.lastname: Umezawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ueda
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ishihara
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ariga
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
keywords: bulk structural transformation; catalysts; intermetallic compounds; polymer membrane electrolyte fuel cells; surface energy