Tin Oxide/Nitrogen-Doped Graphene Quantum Dots Composite Nanotubes: An Efficient Electrode for Supercapacitors

Tin oxide (SnO2) and nitrogen-doped graphene quantum dots (N-GQDs) composite nanotubes (SnO2/N-GQD NTs) were fabricated by the electrospinning technique and followed by the thermal annealing method for the application in supercapacitor as an electrode. SnO2/N-GQD NTs with different ratio of N-GQDs were prepared by adding different ratios of N-GQDs along with tin chloride during the electrospinning process. The prepared composite's structure and morphological properties were characterized by using different techniques like XRD, FE-SEM, TEM, and XPS. The supercapacitor performance of the SnO2/N-GQD NTs composite was analyzed by the electrochemical studies such as cyclic voltammetry and galvanostatic charge-discharge (GCD) measurement in 2 M KOH solution as electrolyte. The electrochemical analyses of SnO2/N-GQD NTs was tested at different scan rates and current densities. SnO2/N-GQD NTs prepared using 3 wt.% of N-GQDs showed an excellent capacity retention even after 5000 GCD cycles and exhibited a maximum specific capacitance of 420 mF g-1 at a current density of 8 mA cm-2 in comparison to pure SnO2 NTs (230 mF cm-2).