Preparation of metallic cobalt–graphene composites with enhanced electrochemical activity

Metallic cobalt–graphene composites were synthesized through coprecipitation synthetic method followed by hydrothermal treatment at 180 °C. The composite material as prepared was characterized using X-ray diffraction (XRD), SEM, TEM, Energy dispersive spectrometer (EDS) analysis and Thermogravimetric (TG) analysis. The results indicate that metallic cobalt particles possess a good dispersion on the surface of graphene. The electrochemical performance of metallic cobalt–graphene composites was characterized by Cyclic voltammetry (CV) and galvanostatic charge–discharge tests. The specific capacitance of the composite material approaches 1340 F g−1 at current density of 1.5 A g−1 with a capacitance retention rate of 82% at current density of 3.5 A g−1. The results suggest that the combination of metallic cobalt and graphene leads to synergistic performance, which inherits the overall system with enhanced electrochemical performance.

► Metallic cobalt–graphene composites were synthesized through two-step method. ► The addition of graphene prevents the agglomeration of metallic cobalt particles. ► The specific capacitance of metallic cobalt–graphene composites is 1340 F g−1. ► The synergistic effect enhances electrochemical performance of metallic cobalt.