Improving the electrochemical characteristics by synergy effect of MoO₃-Nb₂O₅ nanocomposite for high energy supercapacitor

The development of high-performance supercapacitor electrodes has been intensely explored for future high-power storage applications, especially in light of the looming depletion of fossil fuels and the need for renewable resources. Herein, a nanocomposite of molybdenum trioxide-niobium pentoxide (MoO₃-Nb₂O₅ NC) was synthesized using a straightforward ultrasonication procedure. The synthesized MoO₃-Nb₂O₅ NC’s crystallinity, purity, surface texture, morphology, atomic composition, and electronic state were evaluated using various analytical techniques including XRD, FT-IR, FE-SEM, HR-TEM, EDX, and XPS. Further, the cyclic voltammetry (CV) study indicates that the MoO₃-Nb₂O₅ NC offers a high specific capacitance of 1213 F/g at 10 mV/s scan rate. The electrochemical impedance spectroscopy (EIS) of MoO₃-Nb₂O₅NC provides data on the charge transfer resistance (R_ct) and solution resistance (R_s). Furthermore, galvanostatic charge–discharge (GCD) analysis displays extended charge–discharge times and commendable rate capability for the MoO₃-Nb₂O₅ NC, with a specific capacitance of 853 F/g at a current density of 1 A/g. Moreover, the cyclic stability of the MoO₃-Nb₂O₅ NC exhibits superior capacitive retention of 93.3% even after 3000 extended cycles. The asymmetric supercapacitor (ASC) device, based on MoO₃-Nb₂O₅//AC, delivers an energy density of 22.1 Wh/kg at a corresponding power density of 2206 W/kg. Impressively, the MoO₃-Nb₂O₅//AC ASC device maintains superior cyclic stability of 92.6% even after 5000 consecutive charge–discharge cycles.