Dissected carbon nanotubes functionalized by 1-hydroxyanthraquinone for high-performance asymmetric supercapacitors

In the present paper, 1-hydroxyanthraquinone (HAQ) has been adsorbed onto dissected carbon nanotubes (rDCNTs) with reduced graphene oxide layers through noncovalent interaction. As a result, we realized the functionalization of rDCNTs, which means multi-electron electrochemical active groups have been transplanted to the carbon-based materials to further improve the pseudocapacitance. The surface area of dissected carbon nanotubes is increased by several times compared to MWCNTs by an oxidative unzipping process while the conductive backbones of MWCNTs are preserved. The special structure and electrical conductivity of the composites guarantee an outstanding super-capacitive performance for the as-prepared material. In the three-electrode configuration, the HAQ-functionalized rDCNTs (HAQ-rDCNTs) electrode exhibits a higher specific capacitance value (as high as 324 F g−1 at 1 A g−1, two times higher than bare DCNTs) and an ultrahigh rate capability (77.7% capacitance retention at 50 A g−1) in aqueous electrolyte solutions. For further practical application, a novel asymmetric supercapacitor (ASC) has been assembled by using DCNTs as the positive electrode and HAQ-rDCNTs as the negative electrode in a H2SO4 electrolyte. As the result, the device shows an excellent energy storage performance. At a voltage of 1.4 V, the as-fabricated ASC exhibits a high energy density of 12.3 W h kg−1 at a power density of 700 W kg−1.