The electrochemical profile and supercapacitor material performance were evaluated to further understand the features of the VG-M material and explore its potential application. VG-M and VG-S working electrodes were fabricated via a simple dropcasting method (active material loading mass is ~0.2 mg) for electrochemical measurement in 1M H2SO4 electrolyte (Figure ). Cyclic voltammetry (CV) was carried out to determine the electrochemical profiles of the fabricated electrodes. As shown in Figure , the CV curves of VG-M and VG-S at a scan rate of 100 mV/s both presents as a nearly flawless rectangle within a pair of symmetric and broad redox. Such shape indicates their combined mechanism of electrical double-layer capacitance (EDLC) and pseudo-capacitance. The pseudo-capacitance behavior can be attributed to the Faradaic reactions introduced by the residual oxygen functionalities. The CV curves with different scan rates are shown in Figure . The capacitive contribution of VG-M was calculated as ~75.8% at 100 mV/s (Figure ) according to a kinetic calculation, which strongly supports its capacitance-controlled charge storage mechanism. Galvanostatic charge-discharge (GCD) was also performed to evaluate the performance of the materials (Figure ). The capacitance performance and rate capability can thus be obtained via GCD. As shown in Figure , VG-M has a highest specific capacitance of 174 F/g at 1 A/g, and has a high retention of 75.9% at 40 A/g, while VG-S has a significantly lower capacitance of 19 F/g and a slightly higher retention at 40 A/g. Cycle performance of VG-M was measured by applying GCD with a current density of 40 A/g, and a high retention of 93% can be achieved after 10,000 cycles (Figure ).