Facile synthesis of cobalt oxide/reduced graphene oxide composites for electrochemical capacitor and sensor applications

•Co3O4 anchored onto reduced graphene oxide via hydrothermal method.•The composite showed a low detection limit of 0.62 μM for the H2O2 sensor.•The composite exhibited a high specific capacitance of 545 F g−1 at 0.5 A g−1.

Reduced graphene oxide sheets decorated with cobalt oxide nanoparticles (Co3O4/rGO) were produced using a hydrothermal method without surfactants. Both the reduction of GO and the formation of Co3O4 nanoparticles occurred simultaneously under this condition. At the same current density of 0.5 A g−1, the Co3O4/rGO nanocomposites exhibited much a higher specific capacitance (545 F g−1) than that of bare Co3O4 (100 F g−1). On the other hand, for the detection of H2O2, the peak current of Co3O4/rGO was 4 times higher than that of Co3O4. Moreover, the resulting composite displayed a low detection limit of 0.62 μM and a high sensitivity of 28,500 μA mM−1cm−2 for the H2O2 sensor. These results suggest that the Co3O4/rGO nanocomposite is a promising material for both supercapacitor and non-enzymatic H2O2 sensor applications.

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