Electrochemical performance enhancement of ZnO/g-C3N4 nanocomposites using urea and thiourea precursors for supercapacitor applications

Abstract

Supercapacitors are becoming strong options for energy storage devices. They offer quick charging and discharging, high density, and long-lasting stability over many cycles. This research focuses on the synthesis of graphitic carbon nitride (g-C₃N₄) and sulfur-doped graphitic carbon nitride using urea (U-g-C₃N₄) and thiourea (TU-g-C₃N₄), respectively, along with the fabrication of ZnO/g-C₃N₄ based nanocomposites for supercapacitor electrode applications. The study aims to enhance electrochemical performance by integrating ZnO with U-g-C₃N₄ and TU-g-C₃N₄ as separate nanocomposites, leveraging their synergistic properties to improve energy storage capabilities. The fabricated ZnO/U-g-C₃N₄ and ZnO/TU-gC₃N₄ nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV–Vis spectroscopy to analyze their structural, morphological, and optical properties. Furthermore, electrochemical tests, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were conducted to evaluate their electrochemical performance. The results indicated that the ZnO/TU-g-C₃N₄ nanocomposites achieved an impressive specific capacitance of 415F/g at a 50 mV/s, which is significantly higher than the capacitance values observed for ZnO/U-g-C₃N₄ (408F/g) and ZnO (223F/g). Furthermore, ZnO/U-g-C₃N₄ and ZnO/TU-g-C₃N₄ demonstrated superior electrochemical stability, this indicates improved redox activity and superior charge storage ability. The results underscore the potential of ZnO/U-g-C₃N₄ and ZnO/TU-g-C₃N₄ nanocomposites as effective electrode materials for advanced supercapacitor applications.