Co-electrophoretic deposition of Co3O4 and graphene nanoplates for supercapacitor electrode

•Fabrication of Co3O4-graphene nano-composites for supercapacitor, is proposed.•A co-deposition of Co3O4-graphene via elctrophoretic deposition method is proposed.•The co-deposition with different morphology and size in EPD process is considered. In this work, we used the electrophoretic deposition (EPD) technique for the fabrication of Co3O4-Graphene nano-composite as the binder-free electrode for electrochemical supercapacitors. Cobalt nitrate salt was used as the charging agent for EPD of graphene, Co3O4, and their co-deposition. Characterization of the obtained layer by optical microscopy and scanning electron microscopy (SEM) revealed that there was no deposition in the suspension without additive such as nitrate cobalt salt, whereas a uniform layer was formed in the presence of nitrate cobalt salt. Energy dispersive spectroscopy (EDS) analysis of the graphene coating deposited via EPD approved the successful electrodeposition of Co nano-petals between graphene nano-plates. Cyclic voltammetry (CV) was done for measuring the capacitance of the deposited layer in the range of 10–100 mVs−1. The Co3O4 and Co3O4-Graphene nano-composite revealed 236.5 and 319.6 F g−1 at 10 mVs−1 scan rate, respectively. Enhancement in the specific capacitance of the composite was attributed to association graphene in the microstructure.