Preparation And Characterization Of Helical Mesoporous Carbonaceous Nanotubes

In recent years, chiral carbonaceous nanomaterials have attracted much attention of researchers owing to their optical activity and potential application in enantioseparation.Building pore structures on the basis of it can increase specific surface areas thus expanding their application fields. Therefore, the main work in this paper is preparing single-handed helical mesoporous carbonaceous nanotubes with a dual-templating method for the first time. That is to control the structure of single-handed helical nanotubes and porous in walls using supramolecular self-assemblies and silica, respectively. And we studied their application in lithium-ion batteries. Meanwhile the relationship among circular dichroism（CD）, diffuse transmission CD（DTCD） spectra and diffuse reflectance CD（DRCD） spectrum was created based on a low-molecular-weight gelator at hydrogel state. The research work is shown as following:Firstly, a series of bola-type alanine derivatives were synthesized. All of them can cause hydrogels. According to the hydrogel of LL-10Ala11 PyClO₄, the relationship among CD, DTCD and DRCD spectra was studied. The results indicated that the CD and DTCD spectra were almost the same, but the DRCD spectrum was different from them. Based on the TD-DFT calculated CD spectrum, the DRCD spectrum was more accurate. The difference mainly came from light scattering driven absorption flattening.Secondly, left-handed helical resorcinol-formaldehyde resin/silica（RF Resin/SiO₂）nanotubes were prepared using the self-assemblies of LL-12Ala11 PyClO₄ as the template,resorcinol, formaldehyde and tertraethyl orthosilicate（TEOS） as precursors. RF Resin/SiO₂ nanotubes were carbonized to prepare carbon-silica（C/SiO₂） nanotubes. After removal of silica, left-handed helical mesoporous carbonaceous nanotubes were obtained.The wall of carbonaceous nanotubes was amorphous carbon. As an electrode in lithium-ion batteries, their specific discharge capacity was 1345 mAhg^-1 after 77 cycles at a currentdensity of 100 mAg^-1 and coulombic efficiency was 96.6 %. The result indicated helical mesoporous carbonaceous nanotubes displayed good cycling performance and high rate capability.Thirdly, right-handed coiled RF Resin/SiO₂ tubular nanoribbons were prepared using the self-assemblies of D-18Val8 Py Br as the template, resorcinol, formaldehyde and TEOS as precursors. After carbonization and removing of silica, right-handed coiled carbonaceous tubular nanoribbons were obtained. The CD spectra indicated that both RF Resin/SiO₂ and carbonaceous tubular nanoribbons exhibited optical activity. The optical activity might be originated from chiral defects within the walls of the nanotubes.