Fabrication of electrochemically reduced graphene oxide/cobalt oxide composite for charge storage electrodes

• Composite (reduced graphene oxide (Er-GO) and Co3O4) electrodes were electrodeposited by cyclic voltammetry.
• The electrodes are formed by Co3O4 nanoflakes and wrinkled Er-GO nanosheets.
• Er-GO/CoOx electrodes show remarkably enhanced electrochemical response when compared to single Er-GO and Co3O4.
• Optimized Er-GO/CoOx composites have a specific capacitance of 608 F g− 1 at 1 A g− 1 in 1 M KOH.

Electrochemically-reduced graphene oxide (Er-GO) and cobalt oxides (CoOx) were co-electrodeposited by cyclic voltammetry, from an electrolyte containing graphene oxide and cobalt nitrate, directly onto a stainless steel substrate to produce composite electrodes presenting high charge storage capacity. The electrochemical response of the composite films was optimized by studying the parameters applied during the electrodeposition process, namely the number of cycles, scan rate and ratio between GO/Co(NO3)2 concentrations in the electrolyte. It is shown that, if the appropriate conditions are selected, it is possible to produced binder-free composite electrodes with improved electrochemical properties using a low-cost, facile and scalable technique. The optimized Er-GO/CoOx developed in this work exhibits a specific capacitance of 608 F g− 1 at a current density of 1 A g− 1 and increased reversibility when compared to single CoOx.