Hybrid electrode composed of multiwall carbon nanotubes decorated with magnetite nanoparticles for aqueous supercapacitors

This work describes a use of a composite nanomaterial which consists of multiwall carbon nanotubes covered by iron oxide nanoparticles as a hybrid electrode in aqueous supercapacitor. The investigated nanomaterial was manufactured in a two-step simple chemical synthesis in which the first step was a functionalization of carbon nanotubes whereas the second one was the deposition of iron oxide. According the morphological and structural characterization, the carbon nanotubes with diameters of 10–40 nm were successfully covered by randomlydispersed magnetite nanoparticles with average diameter of 10 nm. Moreover, the thermogravimetric analysis results indicated that the mass ratio between carbon nanotubes and iron oxide nanoparticles was about 65–35%. The electrochemical performance of studied hybrid electrode was tested in 1M aqueous KCl electrolyte. The highest specific capacitance of 143 F g‒1 was recorded at a discharge current density of 1 A g‒1. The investigated nanomaterial also exhibited excellent cycling stability i.e. 81% retention of the initial capacitance after 3000 cycles.