## 3 Results  
### Morphology and Structure of CNSs  
The carbonization temperature was found to have a marked influence on the morphology of CNSs. As the pyrolysis temperature was increased from 500 to 1000 \({}^{\circ}\)C, a reduction in particle size was observed (Figure 1A-F), along with the formation of well-developed, spherical, solid carbon aggregates, which is the characteristic feature when the pyrolysis technique is used for the synthesis of carbon particles. The longer duration of synthesis time and controlled cooling rate could be responsible for the formation of spherical-shaped porous carbon nanomaterials. Elemental composition was analyzed via EDS (Figure 2A). As the temperature increased from 500 to 1000 \({}^{\circ}\)C, the carbon content was enriched from \(\sim\)74 to \(\sim\)90% (Table 1). The carbon matrix was also embedded with self-doped oxygen, which continued to decrease in atomic percentage composition from CNS500 to CNS1000 from \(\sim\)20% to \(\sim\)8%, respectively. The CNSs also exhibited the presence of numerous alkali metals such as Na, Mg, K, and Ca, which were found to be present in trace quantities. Figure 2: EDS spectra (**A**), Raman spectra (**B**), and FTIR spectra (**C**) of CNS500, CNS600, CNS700, CNS800, CNS900, and CNS1000 CNSs. CNSs were further analyzed for their structural features using Raman spectroscopy. The CNSs exhibited two prominent peaks (Figure 2B) at \(\sim\)1338 and \(\sim\)1588 cm\({}^{-1}\) corresponding to the D-band and G-band, respectively. The D-band corresponds to vibrations of carbon atoms for in-plane terminations of disordered graphite, indicating disorder in the carbon structure. The G-band signifies the E\({}_{\text{2g}}\) mode of graphite, which could be related to the vibration of sp\({}^{2}\)-bonded carbon atoms in a hexagonal lattice, indicating structural order. The relative intensities of the D-band and G-band (I\({}_{\text{d}}\)/I\({}_{\text{g}}\)) provide an index to assess the graphitic nature of carbon materials [7; 35]. It was found that as the synthesis temperature was increased, the I\({}_{\text{d}}\)/I\({}_{\text{g}}\) value increased, suggesting the presence of more defective sites in CNS1000 (I\({}_{\text{d}}\)/I\({}_{\text{g}}\) = 1.1). This could be due to the greater fragmentation of the particles, creating edges at high temperatures. The liberation of gases such as H\({}_{2}\)O, CO, and CO\({}_{2}\) at elevated temperatures further creates pores in the carbon residue, which contributes to the increased intensity of the D-band. Figure 2C shows the presence of functional groups assessed from FTIR spectra. A broad peak at \(\sim\)3441 cm\({}^{-1}\) indicates the presence of an intermolecularly bonded alcoholic or carboxylic acid --OH group [36]. As the synthesis temperature was increased, the intensity of the peak decreased and disappeared for higher CNSs, suggesting the consumption or removal of the --OH group from the biomass. C=C stretching in carbon was detected by a peak at \(\sim\)1602 cm\({}^{-1}\), which is also similar to --OH group decreases in intensity [37]. --C--H bending vibrations were detected by a peak at \(\sim\)1448 cm\({}^{-1}\), which became more resolved at higher temperatures. S=O stretching was also observed at \(\sim\)1386 cm\({}^{-1}\). The presence of sulfur was also confirmed from the elemental analysis (EDS). However, the peak disappeared after CNS600, suggesting the removal of sulfur as oxides during pyrolysis progression towards higher temperatures. --C--O stretching was also found at \(\sim\)1115 cm\({}^{-1}\), which was also found to disappear at higher synthesis conditions, suggesting that it could have arisen from a secondary alcohol. Further --C--H bending was detected at \(\sim\)874 cm\({}^{-1}\), which could be attributed to the trisubstituted aromatic system, which remained throughout the CNS series and could have been responsible for some order in the carbon matrix [38; 39]. The porosity of the CNSs was analyzed from N\({}_{2}\) adsorption/desorption isotherms.