The electrochemical functionalization and exfoliation of 2H-MoS2 was performed using a natural MoS2 crystal as the cathode and graphite foil as the anode. The aryl diazonium salt used was 4-nitrobenzenediazonium tetrafluoroborate (NBD). 10 mM of NBD and 0.1 M of [TBA][PF6] (tetrabutylammonium hexafluorophosphate) were dissolved in acetonitrile, which was used as an electrolyte for the simultaneous electrochemical exfoliation and functionalization. The MoS2 crystal and the graphite foil were kept at a distance of 2 cm apart and a voltage of 12 V was applied between them. After 30 minutes, the expanded fct-EEM and fct-EEG were dispersed separately in a mixture of isopropanol (IPA) and H2O (1:1 v/v) under the assistance of ultrasonication (2 h). The dispersion was then centrifuged at 4000 rpm. The supernatants of the dispersions were used to fabricate the composite electrodes. The unfunctionalized electrochemically exfoliated MoS2 (EEM) and graphene (EEG) were fabricated using the same method without adding NBD to the solvent. The images of expanded MoS2 before and after the expansion as well as the production procedures can be seen in Figure .