Electrospun cyclodextrin nanofibers as precursor for carbon nanofibers

The carbon nanofibers (CNF) based on the electrospun polymer-free hydroxypropyl-beta-cyclodextrin (HP beta CD) nanofibers were obtained by the combination of chemical and thermal (pyrolysis) treatment. The thermal and chemical decomposition of HP beta CD makes it challenging to obtain persistent CNF from HP beta CD nanofibers. The chemical treatment of HP beta CD nanofibers by using 0.6 mM H2SO4 partially dissolves nanofibers and resulted in fused CNF while direct pyrolysis of HP beta CD nanofibers totally ruins the nanofiber structure and produces char. The partial chemical treatment of HP beta CD nanofibers with 10 mu M H2SO4 dehydrates the top layer of the nanofibers, and a shield-like structure is formed which helps to retain the fibrous morphology during the pyrolysis. The diameter of HP beta CD nanofibers was reduced after carbonization process where CNF having average diameter of 380 +/- 150 nm were obtained. The presence of typical D and G Raman bands and XRD peak at 2 theta ~ 26 degrees further validates CNF formation from HP beta CD nanofibers. The oxygen content is decreased from 34.7 to 5.8%, and carbon content increased from 62.3% to 94.2% after transformation of HP beta CD nanofibers into CNF. To the best of our knowledge, for the first time, this study reports the use of electrospun polymer-free HP beta CD nanofibers as a precursor to produce CNF.