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.