Iron/vanadium co-doped tungsten oxide nanostructures anchored on graphitic carbon nitride sheets (FeV-WO(3)@g-C(3)N(4)) as a cost-effective novel electrode material for advanced supercapacitor applications

In this work, we studied the effect of iron (Fe) and vanadium (V) co-doping (Fe/V), and graphitic carbon nitride (g-C(3)N(4)) on the performance of tungsten oxide (WO(3)) based electrodes for supercapacitor applications. The lone pair of electrons on nitrogen can improve the surface polarity of the g-C(3)N(4) electrode material, which may results in multiple binding sites on the surface of electrode for interaction with electrolyte ions. As electrolyte ions interact with g-C(3)N(4), they quickly become entangled with FeV-WO(3) nanostructures, and the contact between the electrolyte and the working electrode is strengthened. Herein, FeV-WO(3)@g-C(3)N(4) is fabricated by a wet chemical approach along with pure WO(3) and FeV-WO(3). All of the prepared samples i.e., WO(3), FeV-WO(3), and FeV-WO(3)@g-C(3)N(4) were characterized by XRD, FTIR, EDS, FESEM, XPS, Raman, and BET techniques. Electrochemical performance is evaluated by cyclic voltammetry (CV), galvanic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). It is concluded from electrochemical studies that FeV-WO(3)@g-C(3)N(4) exhibits the highest electrochemical performance with specific capacitance of 1033.68 F g(−1) at scan rate 5 mV s(−1) in the potential window range from −0.8 to 0.25 V, that is greater than that for WO(3) (422.76 F g(−1)) and FeV-WO(3) (669.76 F g(−1)). FeV-WO(3)@g-C(3)N(4) has the highest discharge time (867 s) that shows it has greater storage capacity, and its coulombic efficiency is 96.7%, which is greater than that for WO(3) (80.1%) and FeV-WO(3) (92.1%), respectively. Furthermore, excellent stability up to 2000 cycles is observed in FeV-WO(3)@g-C(3)N(4). It is revealed from EIS measurements that equivalent series resistance and charge transfer values calculated for FeV-WO(3)@g-C(3)N(4) are 1.82 Ω and 0.65 Ω, respectively.