Anthraquinone on Porous Carbon Nanotubes with Improved Supercapacitor Performance

Anthraquinone (AQ) molecules were selected to decorate the lab-made hierarchical porous carbon nanotubes (HPCNTs) to obtain electrode materials (AQ-HPCNTs) for supercapacitors, which showed a remarkable capacitance increment in comparison with pure HPCNTs when tested in 1 M H 2 SO 4 aqueous solution. At a current density of 1 A g –1, the AQ-HPCNTs (mass ratio 7:5) electrode showed an ultrahigh specific capacitance of 710 F g –1, which is much larger than that of the unmodified HPCNTs (304 F g –1 ). Even at a high discharge current density of 20 A g –1, the specific capacitance of the AQ-HPCNTs (mass ratio 7:5) electrode was still as high as 419 F g –1, indicating an excellent rate capability. Furthermore, all the AQ-HPCNTs electrodes exhibited a long cycle life. Electrochemical behaviors of AQ on the HPCNTs’ surface showed a double pair of redox peaks, which are appropriate for two types of π–π stacking interactions supported by infrared spectra. The excellent capacitive behaviors of the AQ-HPCNTs electrode materials are due to a strong positive synergistic effect between AQ and HPCNTs on the improvement of electrochemical performances.