Prolific intercalation of VO2 (D)/polypyrrole/g-C3N4 as an energy storing electrode with remarkable capacitance

Abstract

The authors report a fresh synthesis of nanocomposites of VO₂ (D)/polypyrrole/g-C₃N₄ through in situ chemical oxidation polymerization of pyrrole, utilizing FeCl₃ as an oxidizing agent by varying the weight ratio of VO₂ (D) with a fixed amount of g-C₃N₄. In addition, the electrochemical behavior of the synthesized composites was analyzed in 1 M H₂SO₄ electrolyte with the help of cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). According to the statistics of different ratios of VO₂ (D), it plays an indispensable role in the electrochemical properties of the synthesized composites. It has been found that the PGV0.3 sample at a scan rate of 2 mV s⁻¹ shows tremendous specific capacitance of 3263 F g⁻¹ with excellent cycling stability of 99.71% after 2000 cycles, and this value also correlates well with the GCD findings. However, the energy density of PPY at a current density of 0.5 A g⁻¹ is found to be 15.6 W h kg⁻¹, while that of PGV0.3 is 138.2 W h kg⁻¹, which is nearly 8.86 times more than the energy density of PPY. The power densities of PPY and PGV0.3 at a current density of 0.5 A g⁻¹ are found to be 151.7 W kg⁻¹ and 218.69 W kg⁻¹, respectively. The values of solution resistance (R_s) and charge transfer resistance (R_ct) of pyrrole and VO₂ (D) are 5.60 Ω and 3.77 Ω, and 0.34 Ω and 0.11 Ω, respectively, while for PGV0.3 they are 1.28 Ω and 0.07 Ω, respectively. In this way, the authors have witnessed a quite appreciable capacitance furnished through the fabricated and optimized PGV0.3 electrode material in three-electrode and two-electrode systems.