Electrochemical performance of NiCo2O4/functionalized graphene oxide with phenylalanine and tryptophane as efficient electrodes to enhance capacitance properties in supercapacitors

Abstract

In this work, NiCo2O4 is synthesized by the hydrothermal process, then, covalently functionalized aromatic-aliphatic amino acids, including phenylalanine (Phe), and tryptophan (Trp) were added to graphene sheets. Graphene with amino acid modification exhibits stable dispersion in both water and typical organic solvents. Here, we proposed a straightforward and adaptable approach towards the design of NiCo2O4 blending with functionalized graphene oxide (FGO) used as electrochemical electrodes for energy storing applications to improve the electrochemical features such as specific capacitance (Cs), cyclic stability, energy density and power density. To study the nanostructures and characteristics of produced compounds, Fourier-transform infrared spectroscopy (FT-IR), X-ray Powder Diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) images and Brunauer–Emmett–Teller (BET) analysis were utilized. Measurement of electrochemical including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were used to evaluate energy storage efficiency. Measurements of the electrochemical performance display that the specific capacitance (Cs) can reach 1137.7 F. g−1. Furtheremore, it has exceptional cyclic stability, retaining 97.2 % of its capacitance even after 5000 cycles.