Cobalt nanofibers encapsulated in a graphite shell by an electrospinning process

Abstract

As cobalt is an important ferromagnetic material and the nanofibrous shape greatly improves the magnetic properties, we are introducing cobalt nanofibers encapsulated in graphite shell to gain the advantages of the nanofibrous shape as well as to produce protected materials. An electrospun nanofiber mat consisting of cobalt acetate and poly(vinyl alcohol) has been calcined in argon atmosphere at 850 degrees C. Calcination of cobalt acetate in an inert atmosphere leads to the production of pure cobalt which strongly enhanced graphitization of the utilized polymer to form a graphite shell. Physicochemical characterization analyses indicated that the final product was pure cobalt nanofibers enveloped in a 10 nm thick graphite shell. The graphite shell did not affect the magnetic properties of the synthesized graphite-encapsulated cobalt nanofibers compared with the bare ones which reveal preeminent magnetic characteristics; moreover the shell modifies some of these properties to be temperature independent.