Addition of multiwalled carbon nanotube and graphene nanosheet in cobalt oxide film for enhancement of capacitance in electrochemical capacitors

摘要

In order to enhance the capacitance of electrochemical capacitors, multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets (GNS) were added to cobalt oxide (Co _3O _4) paste. The composite film based on Co _3O _4/MWCNT/GNS (95:4:1 wt%) exhibited a capacitance of 294 F/g while the capacitance of Co _3O _4/MWCNT (95:5 wt%) and pure Co _3O _4 film is 205 and 163 F/g, respectively. The enhanced capacitance of Co _3O _4/MWCNT/GNS composite film was attributed to the electrochemical contributions of the Co _3O _4 nanoparticle attached to the GNS as well as their significantly increased specific surface areas by MWCNTs. Furthermore, the composite films showed faradaic redox capacitive behavior to double-layer capacitive behavior due to the different nanostructures of the composites.