Preparation of cobalt hydroxide nanosheets on carbon nanotubes/carbon paper conductive substrate for supercapacitor application

Multi-walled carbon nanotubes grown on the carbon paper substrate are prepared by in situ growth in a chemical vapor deposition system. Co(OH)2 is deposited on carbon nanotubes/carbon paper by electrodeposition methods. SEM images show that the successful growth of nanometer-sized Co(OH)2 nanosheets on the surface of carbon nanotubes/carbon paper substrate. The electrodes of Co(OH)2/carbon nanotubes/carbon paper composite are investigated for their use in supercapacitors with cyclic voltammograms, chronopotentiometric measurements and electrochemical impedance spectroscopy. The composite electrode shows the largest specific capacitance of 1083 F g−1 at a current density of 0.83 A g−1 in 6 M KOH electrolyte. Furthermore, this composite exhibits good cycling stability and lifetime. The implanted CNTs between carbon paper and Co(OH)2 act as a good conductive medium for electrodes in supercapacitors, and the interconnected nanosheets of the Co(OH)2 can facilitate the contact of the electrolyte with active materials, and thus increase the capacitance.