Synthesis of three-dimensional mesoporous Cu-Al layered double hydroxide/g-C₃N₄ nanocomposites on Ni-foam for enhanced supercapacitors with excellent long-term cycling stability

In this study, a novel composite of Cu-Al layered double hydroxide (LDH) nanosheets and g-C₃N₄-covered Ni-foam was fabricated via a simple and facile two-step process. First, g-C₃N₄ sheets were deposited on Ni-foam by via electrodeposition method on a three-electrode system (Ni-foam@g-C₃N₄) and then, Cu-Al LDH nanosheets were grown on the Ni-foam via in situ redox reaction using a hydrothermal process (Ni-foam@Cu-Al LDH/g-C₃N₄). The FE-SEM image confirmed that the Cu-Al LDH nanosheets arose vertically and were anchored on the surface of electrodeposited g-C₃N₄ sheets, thus generating unique 3D porous interconnected networks. The electrochemical capacitive performances of the as-prepared samples were evaluated by cyclic volatammetry (CV), galvanostatic charge/discharge tests, and electrochemical impedance spectra (EIS) Nyquist plots. The specific capacitances of the Ni-foam@Cu-Al LDH/g-C₃N₄ nanocomposite measured from the CV curve (770.98 F g^-1 at 50 mV s^-1) and the galvanostatic charge/discharge curve (831.871 at 0.4 A g^-1) were significantly higher than the others. Moreover, the Ni-foam@Cu-Al LDH/g-C₃N₄ nanocomposite revealed a remarkable high-current capacitive behavior and the capacitance retention could be maintained at 92.71% even after 5000 cycles of CV. Thus, the obtained results demonstrated that the as-prepared nanocomposite has great potential to be used as a novel supercapacitor electrode.