Functional helical silica nanofibers with coaxial mixed mesostructures for the fabrication of PtCo nanowires that display unique geometry-dependent magnetism

Abstract

Helical mesoporous silicas are notable from a self-assembly and applications points of view. We report a novel confinement-free synthesis of chloropropyl-functionalized helical mesoporous silica nanofibers (CP-HMSNFs) possessing straight channels at the fiber center surrounded by concentric short-pitch helical channels. The chloropropyl groups are found mainly distributed at the central cylindrical portion of the fibers, allowing the selective inclusion of guest species to fabricate novel nanocomposite fibers. Moreover, the chloropropyl-functionalized nanofibers were applied as a hard template to fabricate helical platinum-cobalt (PtCo) alloy nanowires with small and narrowly distributed radii of gyration. The helical metal nanowires exhibited distinct ferromagnetic properties as compared with their straight counterpart.