▎ 摘　　要

Core shell few-layer graphene-coated magnetic nanoparticles (GCMNPs) were synthesized by catalytic chemical vapor deposition of methane at atmospheric pressure. The GCMNPs, of cobalt and iron dispersed on an alumina support, catalyze themselves the decomposition of methane, which is the source of carbon. The pretreatment conditions influence the final alumina pore size distribution and GCMNP diameter. The nanoparticles' magnetic properties have been found to be strongly dependent on their size. A high-saturation magnetization value of 238 e.m.u./g was found for our monodispersed diameter body-centered-cubic FeCo nano particles. The nanoparticles exhibited a significant capacitive performance, including a specific capacitance value of 367.2 F/g, high energy density of 86 Wh/kg, and excellent cyclability in aqueous electrolyte.