## 3 Results and Discussion  
### Material Characterization  
Field-emission scanning electron microscopy (FE-SEM) using an ULTRA 55 instrument from Carl Zeiss AG, Germany, was employed to study the microstructures and morphology of the samples under vacuum conditions at an accelerating voltage of 20 kV. Before examination, the samples were mounted on carbon-based adhesive tape and coated with a 2 nm thick platinum layer. The SEM image (Figure 1a) displays a significant number of wrinkles and corrugations on the graphene's basal plane, while its fluffy appearance indicates the expansion of inter-sheet packs within numerous carbon layers due to exfoliation [44; 45; 46]. At a higher magnification (Figure 1b), irregular flakes are observed, which are intertwined due to the cohesive force from the \(\pi\)-\(\pi\) stacking of sp3 hybridized carbon atoms. Additionally, the pseudo-color topographic contrast of the SEM image from Mountains(r) surface profiling, Digital Surf, SA. Besancon, France [[https://www.digitalsurf.com/](https://www.digitalsurf.com/)]([https://www.digitalsurf.com/](https://www.digitalsurf.com/)) (accessed on 10 September 2022) (Figure 1c), reveals that the combination of chemical and thermal treatments produced a thin, paper-like material with an extensive surface area and porous channels [47]. Fourier transform infrared (FTIR) spectroscopy (Nicolet IS-50, Thermo Scientific, Waltham, MA, USA) of the sample demonstrated the presence of several oxygen-containing functional groups, such as C-O, C-OH, and C-O-C, at 1658, 1415, and 1125 nm\({}^{-1}\), respectively (Figure 1d) [48]. The low intensity of these bands indicates that thermal treatment has induced graphitization within the carbon framework [49]. The strong, broad band at 3450 cm\({}^{-1}\) confirms the presence of carboxylic functional groups [50]. As expected, the sample has a high carbon content, which is crucial for determining the bonding nature. Furthermore, the combination of chemical and thermal treatments disrupts the structural arrangement and introduces defects, leading to the deconvolution of the C-O and O-C-O  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Model** & **Nonlinear** & **Linear** & **Linear Plot** & **Parameters** \\ \hline \multirow{7}{*}{Langmuir} & & Type-1 & \(\frac{1}{d_{e}}=\frac{k_{1}d_{m}c}{k_{1}d_{e}}+\frac{1}{d_{m}}\) & \(\frac{1}{d_{e}}\) vs. \(\frac{1}{C_{e}}\) & \\  & & Type-2 & \(\frac{1}{C_{e}}=\frac{k_{1}d_{m}}{g}-K_{L}\) & \(\frac{1}{  
bonds [51]. X-ray diffraction (XRD) analysis (D8 Advance, Bruker Corp., Billerica, MA, USA) of the sample revealed a broad peak at 27.34\({}^{\circ}\), indicative of graphitization, which corresponds to an interplanar spacing of 3.7 \(\AA\) (Figure 1e) [52]. An additional peak at 47.92\({}^{\circ}\), associated with the (100) plane, suggests the formation of flake-like structures with crystal sizes less than or equal to 1 nm. Raman spectroscopy (In-Via confocal, Renishaw plc., Wotton-under-Edge, UK) was further performed to investigate the samples' structural features, such as their intrinsic structural disorder (\(I_{D}/I_{G}\) ratio) and crystallite lattice size (\(I_{a}\)) (Figure 1f) [53]. The typical \(D\) and \(G\) bands were observed at 1350 and 1586 cm\({}^{-1}\), respectively, as the defect-inducing chemical exfoliation provided reactive sites within the sample [54]. Consequently, the high \(I_{D}/I_{G}\) ratio of 1.05 is consistent with the chemical exfoliation process, yielding a crystallite lattice size (\(I_{a}\)) of 15 nm [55].