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

Abstract

Cobalt sulphide (Co9S8) nanoparticles clusters embedded in activated graphene foam (AGF) structure were prepared using microwave-assisted hydrothermal synthesis. Morphological characterization of as-prepared Co9S8/AGF showed that Co9S8 composed of cluster (sphere)-like nanoparticles 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 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. Co9S8/AGF composite showed significant improvement on the specific capacitance compared to pure Co9S8 and specific capacitance values found in previously published reports by other studies for cobalt sulphidebased composites.