*2.4. Charaterization and Electrochemical Performance Evaluations*

The crystal structure of AC and NAC composition was determined using a X-ray diffraction pattern (XRD PANalytical, X'Pert-PRO MPD using Cu Kα radiation) at a wavelength of 0.15406 nm with an angle θ ranging from 10◦ to 70◦ . The scanning step size was 0.02◦ , and also the rate of scanning was 0.1 s per step. Raman spectroscopy (Laser Raman Spectrometer, China). Raman spectra were recorded using 523 nm laser source, at wavelength ranging from 500 to 2700 cm−<sup>1</sup> . The different functional groups and vibrational modes associated with the (AC and NAC) material were studied using FTIR analysis in the range of 400 to 4000 cm−<sup>1</sup> . The SEM and Raman spectroscopy analysis were carried out to understand the morphology of the material and to know to the presents of defects in the (AC and NAC).

The electrochemical performance was evaluate using three-electrode system CH instrument (model-CHI660D) in aqueous 2M KOH electrolyte. In this configuration, carbon electrodes, platinum (Pt), and Ag/AgCl, were employed as the working, counter, and reference electrodes, respectively. The working electrode concocted by means of active material (AC's and NAC), conducting graphite, and polyvinylidene fluoride (PVDF) were

mixed at a weight percentage of 80:10:10, and N-Methyl-2-pyrrolidone used as a solvent to make a homogeneous slurry. After that, the obtained slurry was coated on a 1\*2 cm<sup>2</sup> nickel foam and then dried at 85 ◦C for 4 h. As prepared working electrode used to evaluate the performance curve of cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) at different scan rates and current densities in the potential range of –1.0 to 0 V. The properties of the electrode such as specific capacitance, energy density, and power density can be calculated from the GCD curves using the below Equations (1)–(3), respectively.

$$\mathbf{C} = \frac{I\Delta\mathbf{t}}{m\Delta\mathbf{V}}\tag{1}$$

$$E = \frac{\text{C } \Delta \text{V2}}{2} \tag{2}$$

$$\mathbf{P} = \frac{E}{\Delta \mathbf{t}} \tag{3}$$

where, *C* = specific capacitance (F g−<sup>1</sup> ), ∆t = discharge time difference (s), *I* = current (mA), *m* = mass of active material in working electrode (mg), ∆V = the discharge voltage window (V), *E* = energy density (Wh kg−<sup>1</sup> ), P = power density (W kg−<sup>1</sup> ).
