Preparation of a Cu-Doped Graphene Oxide–Glutamine Nanocomposite for Supercapacitor Electrode Applications: An Experimental and Theoretical Study

In this study, using graphene oxide (GO), glutamine (G), and Cu(II) nanoparticles, a nanocomposite was prepared. Then, the prepared nanocomposite was checked out by various techniques such as X-ray diffraction, Fourier transform infrared, Raman spectrum, scanning electron microscopy, and energy-dispersive X-ray, and the results showed that the desired structure was successfully prepared. Also, a three-electrode system was utilized to measure the electrochemical properties. The specific capacitance of a Cu-doped graphene oxide-glutamine nanocomposite (Cu/G-GO) of 1838 F g^–1 was obtained in a 1 M H₂SO₄ aqueous electrolyte under a current density of 3 A g^–1. Moreover, 85.43% of the initial capacitance of the electrode was preserved after 5000 cycles at 20 A g^–1 (10,000 cycles, 73.12%). Also, the quantum capacitance and the layer distance of GO and G-GO using density functional theory were calculated.