## 3 Results and Discussion
### Structural Properties  
XRD analysis was used to determine any change in the alanate crystalline structure upon surfactant stabilization (Figures S18 and S19). XRD analysis revealed that all of the synthesized materials retained the same crystalline structure as their pristine counterpart. Notably, some broadening of peaks and the reduction in the crystalline sizes (Table S2) compared to the bulk materials were observed and this would be consistent with the formation of smaller particles size upon surfactant stabilization. However, neither the surfactant nor any by-products were detected by XRD. The synthesized materials were further analyzed by FTIR to confirm the presence of surfactants and any compositional changes that were not visible by XRD. All of the as-synthesized LiAlH\({}_{4}\) and NaAlH\({}_{4}\) nanostructures displayed a typical Al-H stretching and bending between 1600 and 1800 cm\({}^{-1}\) and between 700 and 900 cm\({}^{-1}\), respectively (Figures 7 and 8) [68; 69]. The existence of the surfactants was confirmed by the C-H stretching modes observed between 3000 and 2840 cm\({}^{-1}\). These peaks correspond to the  
Figure 6: Morphological evolution of TDA-directed formation of (**a**–**d**) LiAlH\({}_{4}\) nanostructures and (**e**–**h**) NaAlH\({}_{4}\) with an increase in concentration. alkyl chain in the surfactants [41]. For LiAlH4 and NaAlH4 stabilized by HXA, DDA, and ODA, the broad stretching vibrational between 3360 and 3200 cm\({}^{-1}\) and between 1250 and 1020 cm\({}^{-1}\) were assigned to the -NH and -CN stretching of the amine group, respectively. For NaAlH4 stabilized by HTT, DDT, and ODT, small vibrations corresponding to the -SH stretching of thiol group were observed at 2574, 2576, and 2578 cm\({}^{-1}\), respectively [41]. Surprisingly, there is no evidence of the thiol stretching mode between 2600 and 2550 cm\({}^{-1}\) in the thiol stabilized LiAlH4 particles. This indicates that the -SH group may have reacted with LiAlH4 to form a thioalkyl derivative as shown in reaction (2) [70]. Also, the AlH4 stretching modes of the LiAlH4-HTT-10, LiAlH4-DDT-10, and LiAlH4-ODT-10 between 1600 and 1800 cm\({}^{-1}\) were broader as compared to the pristine material, owing to the formation of a LiAlH4-thiol complex [70]. \[\text{LiAlH4}+4\text{RSH}\rightarrow\text{LiAlH4}_{\text{4-n}}(\text{SR})_{ \text{n}}+\text{nH}_{2} \tag{2}\]  
Figure 7: FTIR spectra of LiAlH4 with various surfactants investigated at 10 mM. For LiAlH\({}_{4}\)-TDA, the peaks at 3264 and 1124 cm\({}^{-1}\) were attributed to O-H and C-O vibration of a primary alcohol. In addition, no C=O stretching mode was observed. This further proved the reduction of the carboxylic group upon the stabilization of LiAlH\({}_{4}\) with TDA as per reaction (1). Similarly, TDA stabilized NaAlH\({}_{4}\) displayed stretching modes at 3322 and 1105 cm\({}^{-1}\) attributed to the alcohol group. For NaAlH\({}_{4}\)-TBAB, the peak at 1443 cm\({}^{-1}\) was assigned to the tetra butyl groups of TBAB [71]. It is noteworthy that the shift in C-H vibrational frequencies can be used to determine the conformational order of the surfactant molecules on the surface of the alanate particles [72]. Comparing the C-H asymmetric (2912-292 cm\({}^{-1}\)) and symmetric (2849-2861 cm\({}^{-1}\)) stretching modes of the surfactant stabilized alanate particles with that of the surfactants in a solution, it was found that the C-H vibrational modes of LiAlH\({}_{4}\) and NaAlH\({}_{4}\) stabilized by HXA and DDA all shifted to higher frequencies [40]. This was taken as an indication for an increase in carbon chains 'gauche defects, where the surfactants are in a disordered arrangement or liquid-like structure. As for LiAlH\({}_{4}\)-ODA, NaAlH\({}_{4}\)-DDT, NaAlH\({}_{4}\)-TBAB, and NaAlH\({}_{4}\)-TDA, the CH\({}_{2}\) stretching observed at a lower wavenumber, suggests a decrease  
Figure 8: FTIR spectra of NaAlH\({}_{4}\) with various surfactants investigated at 1 mM.