To make the device, super-long vertically aligned CNTs (VACNT) were first synthesized by water-assisted chemical vapor deposition (CVD) and then transformed into HACNTs using a roller. Next, through an electrochemical deposition process, GQDs were uniformly anchored on the surface of the CNTs, which produced a porous structure. Finally, the as-synthesized GQD/CNT composite film was assembled in a symmetrical two-electrode configuration to fabricate a supercapacitor.

The device retained its initial capacitance after 1,000 charge-discharge cycles and no obvious degradation in the capacitance could be observed during the cycling experiment. This confirms the good affinity of electrodeposited GQDs to the HACNT scaffolds.

Full details can be found in the journal Nanotechnology.