From carbon nanotubes to functional graphene nanoribbons for high performance supercapacitors

Graphene nanoribbons (GNRs) have great application potential as electrode materials for supercapacitor because of their edge-enriched active surface area, excellent conductivity and unique structure. Here, functional GNRs were prepared by the oxidation unzipping of carbon nanotubes (CNTs) with followed low-temperature heat treatment. Benefiting from the unique one-dimensional structure, a large number of oxygen functional groups (14.41 at.%), and superior specific surface area (184.44 m2 g-1), the optimized GNR-200 electrode achieves a high specific capacitance of 225.9 F g-1 at 0.5 A g-1, which is five times better than that of pure CNTs (39.6 F g-1). Most importantly, the assembled GNR-200//GNR-200 symmetric supercapacitor delivers an energy density of 15.52 Wh kg-1 and good electrochemical stability with the capacitance retention of 92.85 % after 20,000 cycles.