## 3 Results and Discussion
### Fourier-Transform Infrared Spectroscopy  
The nature and symmetry of functional groups of CSHIDS, CSLDH-1 and CSLDH-2 have been identified by the FT-IR technique, as shown in Figure 7. Figure 7a shows the spectrum of CSHDS. The interlayered anions of CSHDS were confirmed by the appearance of a clear band at 2206 cm\({}^{-1}\) corresponding to the vibrational mode of cyanate (N\(\equiv\)C-O\({}^{-}\)).  
Small two bands were observed at 1388 cm\({}^{-1}\) and 1461 cm\({}^{-1}\), indicating that small amounts of nitrate anions were intercalated among the nanolayers [31; 32]. Hydroxyl groups of CSHDS were also detected by a broad band at 3423 cm\({}^{-1}\). This broadness is due to the hydrogen bonds of the hydroxyl groups. These hydrogen bonds were confirmed by the sharp and strong bands around 2923 cm\({}^{-1}\) because the molecules of the interlayered water which hydrogen-bonded to the interlayered anions caused the stretching mode for the O-H bands [33]. Additionally, the water molecules exhibited the bending mode band close to 1637 cm\({}^{-1}\)[28; 32].  
Figure 6: Schematic representation for transformation of nanolayers to nanofibers.  
In the case of CSLDH-1, Figure 7b shows a strong band at 2217 cm\({}^{-1}\), which was formed due to symmetrical vibration \(\
u_{1}\) of NCO. Additionally, the clear peak observed at 634 cm\({}^{-1}\) could be attributed to the \(\
u_{2}\) form of cyanate ion. An important phenomenon is observed for the existence of NCO ions inside the interlayers beside OH groups [33]. It revealed that there is a strong effect of the electron density of NCO on the vibration of the OH groups. The broad OH vibration band which resolved into two bands was ascribed to the existence of the NCO group beside the OH groups. The unaffected OH groups showed an absorption band at 3629 cm\({}^{-1}\), as reported for the usual hydroxyl groups. Additionally, there is another band which was observed at a lower value of 3467 cm\({}^{-1}\). The shifting of the band of the hydroxyl group was due to the lowering of the O-H bond electron density because of the effect of the cyanide group. This phenomenon is in agreement with the results of [PERSON] et al. [34] that indicated the outcome of the existence of nitrate ions on the bands of LDH. The shoulder peaks recorded at 2925 cm\({}^{-1}\) indicate the stretching OH bonds that are due to the interlayer water molecules and/or produced from the hydrogen bonds formed with cyanate ions [15; 26; 35; 36]. The peak at 1617 cm\({}^{-1}\) was due to the bending band of the water molecules [37]. Additionally, the weak peaks observed at both 1457 cm\({}^{-1}\) and 1384 cm\({}^{-1}\) indicated that there are traces of nitrate as secondary anions.  
Figure 7c showed that the sample CSLDH-2 has the main bands of LDH's structure in the case where the guests are nitrate anion. Clear bands for nitrate anions were observed at 1384 cm\({}^{-1}\) and 1457 cm\({}^{-1}\). Additionally, the hydroxyl band and water band were observed at 3434 cm\({}^{-1}\) and 1637 cm\({}^{-1}\). The hydrogen bonds were confirmed by strong bands at 2923 cm\({}^{-1}\) and 2852 cm\({}^{-1}\), indicating that the nitrate anions bonded with hydroxyl groups through H-bonds.