The Effect of Nitrogen on the Capacitive Properties of N-Doped rGO/CuCr<sub>2</sub>O<sub>4</sub> Composites as Materials for Supercapacitors

Abstract

A hybrid supercapacitor is an energy storage device that combines the properties of EDLCs and pseudocapacitors. In this research, the goal was to analyze the effect of hydrothermal temperature on the structure, morphology, and capacitive properties of the N-Doped reduced graphene oxide/Copper Chromite (N-Doped rGO/CuCr2O4) composite, which was being investigated as a potential material for hybrid supercapacitor electrodes. The method used was hydrothermal, with temperature variations of 120°C, 140°C, and 160°C. The structure and morphology of the composites were analyzed using Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX), X-Ray Diffractometer (XRD), and Fourier Transform Infrared Spectrometer (FTIR). Meanwhile, the capacitance and conductivity values of N-doped rGO/CuCr2O4 were measured using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) tests. The results of the XRD tests showed that an increase in temperature led to a greater dspacing value, indicating the presence of more substituted nitrogen atoms. This was supported by the results from EDX, which showed that the sample with a hydrothermal temperature of 160°C had the largest percentage of nitrogen. Nitrogen is important in increasing the conductivity of the material. The FTIR results revealed a covalent bond between Carbon (C) and Nitrogen (N). Meanwhile, the results of the CV test, performed at a scan rate of 5 mV/s and a potential window of 0-0.8 V, showed that the specific capacitance values were 99.5, 196.16, and 221.59 Fg-1 for the samples with hydrothermal temperatures of 120°C, 140°C, and 160°C, respectively. The EIS test measured the conductivity values of the samples, which were 0.123, 0.518, and 0.549 S/m for the samples with hydrothermal temperatures of 120°C, 140°C, and 160°C, respectively. Thus, the specific capacitance values were influenced by the electrical conductivity of the materials and the nitrogen doping content in the electrode composite material.