title: Redox-transmetalation process as a generalized synthetic strategy for core-shell magnetic nanoparticles.
abstract: Although multicomponent core-shell type nanomaterials are one of the highly desired structural motifs due to their simultaneous multifunctionalities, the fabrication strategy for such nanostructures is still in a primitive stage. Here, we present a redox-transmetalation process that is effective as a general protocol for the fabrication of high quality and well-defined core-shell type bimetallic nanoparticles on the sub-10 nm scale. Various core-shell type nanomaterials including Co@Au, Co@Pd, Co@Pt, and Co@Cu nanoparticles are fabricated via transmetalation reactions. Compared to conventional sequential reduction strategies, this transmetalation process has several advantages for the fabrication of core-shell type nanoparticles: (i) no additional reducing agent is needed and (ii) spontaneous shell layer deposition occurs on top of the core nanoparticle surface and thus prevents self-nucleation of secondarily added metals. We also demonstrate the versatility of these core-shell structures by transferring Co@Au nanoparticles from an organic phase to an aqueous phase via a surface modification process. The nanostructures, magnetic properties, and reaction byproducts of these core-shell nanoparticles are spectroscopically characterized and identified, in part, to confirm the chemical process that promotes the core-shell structure formation.
authors.affiliation: Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
authors.forename: Woo-Ram
authors.initials: WR
authors.lastname: Lee
authors.forename: Min Gyu
authors.initials: MG
authors.lastname: Kim
authors.forename: Joon-Rak
authors.initials: JR
authors.lastname: Choi
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Park
authors.forename: Seung Jin
authors.initials: SJ
authors.lastname: Ko
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Oh
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Cheon