Self-assembled reduced graphene oxide/carbon nanotube thin films as electrodes for supercapacitors

Abstract

Graphene oxide/carbon nanotube (GO/CNT) hybrid films are self-assembled on a Ti substrate via simple casting of aqueous dispersion. The amphiphilic nature of graphene oxide sheets allows adsorption of CNTs onto their surface in water, capable of forming a highly stable dispersion. Binder-free electrodes are prepared using the annealed GO/CNT films for high performance supercapacitors. The hybrid film electrodes with a moderate CNT content, typically 12.5 wt%, give rise to remarkable electrochemical performance with extremely high specific capacitances of 428 and 145 F g⁻¹ at current densities of 0.5 and 100 A g⁻¹, respectively, as well as a remarkable retention rate of 98% of the initial value after 10 000 charge/discharge cycles. The synergistic effects arising from (i) the enlarged surface area of electrodes due to the intercalation of CNTs between the stacked GO sheets with associated large electrochemical active sites and (ii) the improved conductivity through the formation of a 3D network aided by CNTs are mainly responsible for these findings.