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

摘要

Platinum–cobalt nanowires can be constructed into twisted, magnetically active helical shapes using a novel silica template. Mesoporous silica is a sieve-like material, ideal for directing the growth of metal nanowires. Previously, researchers have developed helical mesoporous silicas to grow spiral metal nanowires. Now, Chia-Min Yang from National Tsing Hua University in Taiwan and co-workers have made these templates more versatile. By introducing silanes bearing chloropropyl groups into the synthesis mixture, the materials self-assembled into nanofibres having a straight central core surrounded by concentric short-pitch helical channels. Because the hydrophobic chloropropyl groups localized near the nanofibre core, the team used them to selectively deposit various materials into the helical templates — iron oxide, pure platinum metal and ferromagnetic platinum–cobalt nanocomposites with possible high-density storage applications.