## 3 Results and Discussion  
### Structural Characterization and Morphology  
The XRD patterns of PC and APC are shown in Figure 3. PC displays a broad (002) reflection with an interlayer spacing (d\({}_{002}\) = 0.39 nm) indicative of amorphous carbon [22; 23]. APC also appears amorphous-exhibiting; however, it has an even broader (002) reflection at higher d\({}_{002}\) = 0.42 nm [22]. This, as expected, signals a higher degree of amorphousness and defect concentration for the chemically activated carbon. APC additionally contains X-ray detectable traces of residual K\({}_{2}\)CO\({}_{3}\) as a result of carbon reaction with KOH [8; 9]. Carbonates were also evident by infrared spectroscopy (not shown). Its persistent presence even after acid treatment of the solid with HCl and HF implies, rather, that some K\({}_{2}\)CO\({}_{3}\) crystallites might be entrapped inside the carbon matrix. Note also that the shape of the (002) peak is asymmetric in both samples. This asymmetry is related to the existence of closely spaced peaks of different intensities, generated by different carbon turbostrates [24]. Overall, the obtained carbons resemble the amorphous character of low-temperature wood-derived carbons [25]. Figure 3: XRD patterns of the PC (**a**) and APC (**b**) powders. APC additionally contained traces of residual K\({}_{2}\)CO\({}_{3}\). The amorphous character of PC and APC is additionally confirmed by Raman spectroscopy [26] (Figure 4). PC shows the typical G and D carbon bands at 1590 cm\({}^{-1}\) and 1375 cm\({}^{-1}\), respectively, whereas the same bands appear downshifted at 1587 cm\({}^{-1}\) and 1353 cm\({}^{-1}\) for APC [27; 28; 29]. In both cases, the Raman bands are broader than those of crystalline graphite. The full-width at half maximum FWHM of the D band in either PC or APC is nearly 100 cm\({}^{-1}\) vs. 60 cm\({}^{-1}\) for crystalline graphite, while the corresponding FWHM of the G band in either PC or APC is nearly 70 cm\({}^{-1}\) vs. 15-35 cm\({}^{-1}\) for crystalline graphite. In respect to the relative intensity ratio of the two bands I\({}_{\rm D}\)/I\({}_{\rm G}\), this equals to 0.68 for PC and 0.77 for APC; i.e., the graphitization degree is higher in PC than APC, in accordance with the XRD results. These ratios are considerably higher than those of crystalline graphite with I\({}_{\rm D}\)/I\({}_{\rm G}\) = 0.2 [30]. The broadness of the bands together with the relatively high I\({}_{\rm D}\)/I\({}_{\rm G}\) intensity ratio is typical of amorphous carbon [26]. According to the SEM study, PC consists of perfectly aligned stacks of large plates with flat and compact surface morphology (Figure 5). According to AFM, the flat plates are actually made of carbon nanosheets with an average thickness of 3 nm (Figure 6). The formation of carbon nanosheets could be rationalized as the following: (i) nanosheets are the closest existing analogue to thermodynamically stable graphite with platy morphology, and (ii) the wood casing in pencils is engineered wood with a unique compressible lamellar structure. With respect to the structure of the amorphous nanosheets, these are expected to be composed of stacks of incompletely crystallized carbon layers in turbostatic ordering, consisting of both aliphatic and aromatic regions and containing either structural O heteroatoms within the carbon matrix or/and -OH/C=O functional groups on the outer surface. Figure 4: Raman spectra of PC (black line) and APC (red line), showing the characteristic D and G carbon bands from left to right. Figure 5: SEM images of the PC sample. (**a**) Magnification \(\times\)4000, scale 5 \(\upmu\)m, (**b**) magnification \(\times\)1500, scale 10 \(\upmu\)m, (**c**) magnification \(\times\)3000, scale 5 \(\upmu\)m.  
Figure 6: (**a**) AFM image of cross-sectional analysis of selected carbon nanosheet in PC sample, (**b**) AFM statistical analysis of thickness for 30 randomly selected nanosheets.