High-Performance Ni(II)@Amine-Functionalized Graphene Oxide Composite as Supercapacitor Electrode: Theoretical and Experimental Study

Graphene oxide (GO) has been broadly utilized as a starting precursor for electrochemical applications due to its unique tunable characteristics. In this work, a Ni(II)@amine-functionalized graphene oxide composite was introduced as a high-performance supercapacitor electrode theoretically and experimentally. The composite (Ni@A-GO) was fabricated through a facile synthesis route, utilizing nickel stabilized on glutamine. Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) were utilized to characterize the synthesized sample. The first-principle study revealed a significantly higher quantum capacitance of Ni@A-GO than GO. In line with theoretical results, experimental investigation exhibited its high capacitance of 1136 F g(-1) at a 2 A g(-1) current density with a significant capacitance retention of 84% at 5 A g(-1) as well as good stability for 12 000 cycles, in a three-electrode system. Moreover, an asymmetric two-electrode device (Ni@A-GO//AC), assembled using Ni@A-GO as a positive electrode and activated carbon (AC) as a negative electrode, demonstrated an excellent specific capacitance of 478 F g(-1) at 2 A g(-1) with good stability for 5000 cycles, promising its practical application as a high-performance supercapacitor electrode.