Electrochemically reduced graphene oxide/carbon nanotubes composites as binder-free supercapacitor electrodes

• Binder-free electrodes were fabricated with MWCNTs and ecrGO for supercapacitors.
• MWCNTs as “spacers” insert between the graphene sheets to enlarge surface areas.
• GO can be reduced to ecrGO by a facile and controllable electrochemical method.
• The ecrGO/MWCNTs composite (GO:MWCNTs = 5:1) showed the highest Csp.
• The composite (5:1) have high retention of 93% after 4000 charge/discharge cycles.

Binder-free composites of electrochemically reduced graphene oxide (ecrGO) and multiwalled carbon nanotubes (MWCNTs) were fabricated as supercapacitors electrodes operating in aqueous systems. GO was found to be electrochemically reduced according to the XRD and Raman data. Therefore, this facile and controllable method was applied to reduce GO in the GO/MWCNTs composites, generating ecrGO/MWCNTs composites. The ecrGO/MWCNTs composites exhibit higher specific capacitance (Csp) than ecrGO because the intercalation of MWCNTs into ecrGO sheets increases the surface areas, according to the TEM, XRD and N2 adsorption-desorption results. The composites with different mass ratios of GO to MWCNTs (10:1, 5:1, 1:1, 1:5, 1:10) were investigated. The ecrGO/MWCNTs composite (GO: MWCNTs = 5:1) showed the highest Csp from the cyclic voltammetry results at a scan rate of 10 mV s−1, and it expressed Csp of 165 F g−1 at a current density of 1 A g−1 and 93% retention after 4000 cycles of charge/discharge. When the mass ratio of GO to MWCNTs further decreases to 1:10, the Csp of the composites declines, and the ecrGO/MWCNTs composite (GO: MWCNTs = 1:10) performs a nearly pure double-layer capacitor. However, the composites containing more MWCNTs can maintain better capacitive behavior at higher rates of charge/discharge.

Binder-free GO/MWCNTs electrodes were fabricated from graphene oxides (GO) and multiwalled carbon nanotubes (MWCNTs), and then converted to the ecrGO/MWCNTs electrodes for supercapacitors via a facile and controllable electrochemical method. These MWCNTs as “spacers” intercalate between the ecrGO sheets to explore more surface areas of ecrGO, elevating the specific capacitance of ecrGO from 88 F g−1 to 110 F g−1.Figure optionsDownload as PowerPoint slide