Hydrothermal Synthesis of Vanadium Pentoxides–Reduced Graphene Oxide Composite Electrodes for Enhanced Electrochemical Energy Storage

Graphene-based nanomaterials (graphene nanosheets/graphene nanoribbons) decorated with vanadium pentoxide (V 2 O 5 ) nanobelts ( i.e. GVNBs) were synthesized via one-step low-temperature facile hydrothermal/solvothermal method as high-performance electrochemical composite electrodes. VNBs were formed in the presence of graphene oxide (GO), a mild oxidant, which transforms into reduced GO (rGO HT ) assisted in enhancing the electronic conductivity with mechanical strength for GVNBs. From surface sensitive electron microscopy and spectroscopy structural characterization techniques and analyses, rGO HT nanosheets/ nanoribbons appear to be inserted into and coated with the layered crystal structure of VNBs, which further confirmed the enhanced electrical conductivity of VNBs. The electrochemical energy storage capacity of GVNBs is investigated using electrochemistry and the specific capacitance C s are determined from both the cyclic voltammetry (CV) with scan rate and galvanostatic charge/discharge V-t profiles with varying current density. The GVNBs having rGO-rich composite V 1 G 3 (V 2 O 5 /GO = 1:3) showed superior performance followed by V 2 O 5 -rich V 3 G 1 (V 2 O 5 /GO = 3:1) as compared with V 1 G 1 (V 2 O 5 /GO = 1:1) composites besides pure component (rGO HT and V 2 O 5 ) materials. Moreover, V 1 G 3 and V 3 G 1 composites showed excellent cyclic stability and the capacitance retention of > 80% after 200 cycles. Furthermore, by performing extensive simulations and modeling of electrochemical impedance spectroscopy data, we determined various circuit parameters (charge transfer and solution resistance, double layer and low frequency capacitance). These findings highlight the comparative performance of nanocomposite hybrid electrode materials.