title: Scalable Bromide-Triggered Synthesis of Pd@Pt Core-Shell Ultrathin Nanowires with Enhanced Electrocatalytic Performance toward Oxygen Reduction Reaction.
abstract: This article reports a novel scalable method to prepare ultrathin and uniform Pd@Pt nanowires (NWs) with controllable composition and shell thickness, high aspect ratio, and smooth surface, triggered by bromide ions via a galvanic replacement reaction between PtCl6(2-) and Pd NWs. It was found that bromide ions played a vital role in initiating and promoting the galvanic reaction. The bromide ions served as capping and oxidized etching agents, counterbalancing the Pt deposition and Pd etching on the surface to give final Pd@Pt core-shell nanostructures. Such a counterbalance and the formation PtBr6(2-) with lower redox potential could lower the reaction rate and be responsible for full coverage of a smooth Pt shell. The full coverage of Pt deposited on Pd NWs is important for the enhancement of the activity and stability, which depend strongly on the Pt content and Pt shell thickness. Significantly, the Pd@Pt NWs with Pt content of 21.2% (atomic ratio) exhibited the highest mass activity (810 mA mg(-1)(Pt)) and specific activity (0.4 mA cm(-2)). Interestingly, the mass activity (1560 mA mg(-1)(Pt)) and specific activity (0.98 mA cm(-2)) of Pd@Pt (21.2%) NWs increased to 2.45 and 1.95 times the initial values after 60k cycles tests, 8.5 and 9.0 times greater than those of Pt/C catalysts. In addition, these ultrathin NW electrocatalysts with large aspect ratio are easy to form into a freestanding film, which improves the mass transport, electrical conductivity, and structure stability.
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Hui-Hui
authors.initials: HH
authors.lastname: Li
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Si-Yue
authors.initials: SY
authors.lastname: Ma
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Qi-Qi
authors.initials: QQ
authors.lastname: Fu
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Liu
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Wu
authors.affiliation: Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, The People's Republic of China.
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Yu