2016 Volume 2016 Issue 274 Pages 125-131
Differences in the temperature programed desorption, reduction and oxidation measurements (TPD, TPR and TPO, respectively) are discussed, with respect to the structural changes and the gas evolution behavior of exfoliated carbon fibers (ExCFs). During the TPD measurements, the crystallinity of the ExCFs was noticeably increased, while a smaller crystallinity increase occurred in the case of TPR measurements. This is probably because the edge sites of ExCFs were terminated by hydrogen in the TPR. Since this reaction occurred prior to the desorption of functional groups, their concentration estimated by TPR was much lower than that obtained by TPD. On the other hand, TPO measurements gave more reliable information about the number of functional groups in ExCFs when it was performed after their TPR measurement. The pristine edge structure of ExCFs was well maintained by the hydrogen-termination during TPR measurements, thus avoiding modification of the carbon layers.
