## 3 Results
### ATR-FTIR and Raman Spectra Analysis
Figure 9a displays the first Raman region subjected to Gaussian fit deconvolution analysis. The appearance of the D band around 1470 cm\({}^{-1}\) suggests the presence of structural defects and a disordered carbon structure. In contrast, the G band observed at 1510 cm\({}^{-1}\) indicates the presence of structural graphitic order in the material [40; 41]. The standard Raman shifts for carbon, the D peak around 1350 cm\({}^{-1}\) and the G peak around 1582 cm\({}^{-1}\), are commonly observed in Raman spectra of carbon materials such as graphene and carbon nanotubes. However, it is essential to note that the exact Raman shift values can vary depending on various factors, leading to differences in observed values, as can be observed in Figure 9a. Several factors can contribute to variations in Raman shift values for carbon materials, from the chemical composition of the material and the presence of strain and defects. The chemical composition and structure of the carbon material can influence the Raman shifts. Graphene, amorphous carbon, and carbon nanotubes, for example, can exhibit variations in peak positions due to their distinct lattice structures and levels of disorder [37]. The presence of strain or defects in the carbon lattice can cause shifts in the Raman peaks. Strain can arise from mechanical deformation or interactions with the substrate, while defects can result from impurities, lattice vacancies, or edges. It is also necessary to refer to the instrumental effect, in which laser power, wavelength, and spectral resolution can influence the Raman shifts. Calibration errors or differences in instrument configurations can contribute to discrepancies in the observed peak positions [42]. Even though these are not the only factors that can affect Raman peak positions, it is necessary to consider that these peaks can present different Raman shifts (cm\({}^{-1}\)). Table 2 presents the intensity ratio between the two characteristic bands (I\({}_{\text{D}}\)/I\({}_{\text{G}}\)) mentioned earlier and calculated using the D\({}_{1}\) and G peaks from the first Raman region. The Blue shark gelatine-based carbon has a higher I\({}_{\text{D}}\)/I\({}_{\text{G}}\) ratio (2.11) than the blue shark chondroit sulfate-based carbon, which has a ratio of 1.55, with crystallite sizes of 9 and 12 nm, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Carbon Source** & **R\({}^{2}\)** & **I\({}_{\text{D}}\)/I\({}_{\text{G}}\)** & **La/nm** \\ \hline Blue shark chondroit sulfate & 0.999 & \(1.56\pm 0.02\) & 12.40 \\ Commercial chondroit sulfate & 0.998 & \(1.84\pm 0.06\) & 10.29 \\ Blue shark gelatine & 0.995 & \(2.09\pm 0.04\) & 9.13 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: I\({}_{\text{D}}\)/I\({}_{\text{G}}\) and crystallite size values of the blue shark and commercial-based carbons throughout the peak deconvolution of the Raman spectra in the first Raman region. Figure 9: First Raman region (**a**) and second Raman region (**b**) of the blue shark chondroit sulfate-based carbon (1000 \({}^{\circ}\)C, 1 h). Comparing the two chondroitin sulfate samples, the blue shark source sample exhibits a lower I\({}_{\rm D}\)/I\({}_{\rm G}\) value of 1.56 \(\pm\) 0.02 and a higher crystallite size of 12.40 nm in contrast to the commercial version, which has an I\({}_{\rm D}\)/I\({}_{\rm G}\) ratio of 1.84 \(\pm\) 0.06 and an L\({}_{\rm a}\) value of 10.29 nm. A decrease in the I\({}_{\rm D}\)/I\({}_{\rm G}\) ratio may indicate an increase in the graphitization degree [43]. The I\({}_{\rm D}\)/I\({}_{\rm G}\) for the blue shark gelatine-based carbon is 2\(\times\) higher (2.09 \(\pm\) 0.04) compared to the values presented by [PERSON] et al. [36] (0.96-0.97), probably reflecting distinct characteristics in the gelatine precursors. The observed changes in crystallinity among the three analyzed samples have the potential to cause modifications in the physical properties of the biocarbon. Conversely, increasing crystallinity can be associated with improving the reported capacitance value [44].