title: Synthesis and characterization of 9 nm Pt-Ni octahedra with a record high activity of 3.3 A/mg(Pt) for the oxygen reduction reaction.
abstract: Nanoscale Pt-Ni bimetallic octahedra with controlled sizes have been actively explored in recent years owning to their outstanding activity for the oxygen reduction reaction (ORR). Here we report the synthesis of uniform 9 nm Pt-Ni octahedra with the use of oleylamine and oleic acid as surfactants and W(CO)6 as a source of CO that can promote the formation of {111} facets in the presence of Ni. Through the introduction of benzyl ether as a solvent, the coverage of both surfactants on the surface of resultant Pt-Ni octahedra was significantly reduced while the octahedral shape was still attained. By further removing the surfactants through acetic acid treatment, we observed a specific activity 51-fold higher than that of the state-of-the-art Pt/C catalyst for the ORR at 0.93 V, together with a record high mass activity of 3.3 A mgPt(-1) at 0.9 V (the highest mass activity reported in the literature was 1.45 A mgPt(-1)). Our analysis suggests that this great enhancement of ORR activity could be attributed to the presence of a clean, well-preserved (111) surface for the Pt-Ni octahedra.
authors.affiliation: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
authors.forename: Sang-Il
authors.initials: SI
authors.lastname: Choi
authors.forename: Shuifen
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authors.lastname: Xie
authors.forename: Minhua
authors.initials: M
authors.lastname: Shao
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Odell
authors.forename: Ning
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authors.lastname: Lu
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Peng
authors.forename: Lesia
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authors.lastname: Protsailo
authors.forename: Sandra
authors.initials: S
authors.lastname: Guerrero
authors.forename: Jinho
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authors.lastname: Park
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Xia
authors.forename: Jinguo
authors.initials: J
authors.lastname: Wang
authors.forename: Moon J
authors.initials: MJ
authors.lastname: Kim
authors.forename: Younan
authors.initials: Y
authors.lastname: Xia