Microwave-assisted synthesis of cobalt sulphide nanoparticle clusters on activated graphene foam for electrochemical supercapacitors

Abstract

Cobalt sulphide (Co₉S₈) nanoparticle clusters embedded in an activated graphene foam (AGF) structure were prepared using microwave-assisted hydrothermal synthesis. Morphological characterization of the as-prepared Co₉S₈/AGF showed that Co₉S₈ composed of cluster (sphere)-like nanoparticles was embedded in the matrix of a porous sheet-like AGF. The synergy between the Co₉S₈ nanoparticles and AGF in the Co₉S₈/AGF composite showed predominantly an improvement in the porous nature (surface area and pore volume) of the Co₉S₈ and the electrical conductivity of the composite electrode. The composite exhibited a specific capacitance of 1150 F g⁻¹ as compared to Co₉S₈ with a specific capacitance of 507 F g⁻¹ at a scan rate of 5 mV s⁻¹ and good cycling stability in 6 M KOH electrolyte. The Co₉S₈/AGF composite showed significant improvement in the specific capacitance compared to pure Co₉S₈ and specific capacitance values found in previously published reports by other studies for cobalt sulphide-based composites.