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.

Crystallite sizes of various carbon blacks were evaluated by Raman spectroscopy and X-ray diffraction. Carbon blacks were experimentally produced by the pyrolysis of ethylene or acetylene. The experimental carbon blacks, commercial carbon blacks (#15, AX-015, #60, #51 and #70, ASAHI CARBON CO., LTD.), and the same commercial carbon blacks heated at different temperatures, 1473, 1673, 1873 and 2473 K were examined. The D1/G ratio (i.e. R ratio) and crystallite size L_a were determined from the Raman data and X-ray diffraction patterns, respectively. The R ratio decreased with increasing L_a in the case of L_a>2 nm. This trend is consistent with a previous study in which the R ratio was proportional to 1/L_a, while the proportionality constant was different from the previous study. In the case of L_a<2 nm, the R ratio increased with increasing crystallite size, and the R ratios of the experimental carbon blacks were larger than those of the commercial ones, whereas the R ratios of the heated samples of these experimental carbon blacks were similar to those of the commercial ones. This result is attributed to volatile matter at the particle surface. These results indicate that the R ratio has a maximum value at L_a=2 nm, and it is affected by the surface characteristics of the particles.

Bacterial cellulose (BC) fibers which are produced by acetic acid bacteria and are a well-known biomass resource were used to synthesize carbon nanofibers (CNFs) as a filler of C/C composites. The iodine treatment of BC resulted in large improvements in carbonization yield and surface textural-changes during CNF preparation in comparison with raw BC. The C/C composites were prepared from furan resin with BC fibers and CNFs derived from raw or iodine-treated BC, and their wear properties were examined. Composites filled with 0.5 wt% or more of CNFs obtained from iodine-treated BC showed a lower relative wear volume than C/C composites with BC fiber or CNFs from raw BC. Taking into account the densities, electrical conductivities and SEM observations of the C/C composites with different fillers, it is suggested that the higher wear resistance is related to the unique surface texture of CNFs obtained from iodine-treated BC which improved interface adhesion between the fibers and the matrix.

This review paper describes the etching behavior of various carbon materials by metal nanoparticles (cobalt, nickel or platinum) in a flowing gas mixture of hydrogen and nitrogen (1 : 9) between 700 °C and 1000 °C based on our earlier studies. This study started from the observation of the etching of a carbon black (CB) by PtCo particles in a PtCo/CB catalyst. In a highly oriented pyrolytic graphite (HOPG) catalytic etching with cobalt nanoparticles produced straight channels on the cleavage planes, usually starting at the edges of the planes, and resulting in the formation of methane by the catalytic reaction of HOPG and hydrogen on the metals. In the case of an activated carbon (AC) cobalt nanoparticles etched the inner region of the AC forming many mesopores and channels with graphite-like walls. A boron-doped diamond electrode, a highly oriented {100} diamond coating and synthetic diamond crystallites were also etched by these metal particles, probably in a semi-molten state. The patterning of the {100} planes of diamond with small etch pits containing metal nanoparticles is promising for the development of functional materials, such as agglomerate-proof metal catalysts or new electronic devices.

The aim of this thesis is to clarify the adsorption state of molecules or ions inside micropore of single-walled carbon nanotube (SWCNT). Firstly, we investigated that hydration structure around a zinc ion confined in micropore of activated carbons and SWCNTs by X-ray absorption fine structure (XAFS) technique and clarified the dehydration structure is formed around a zinc ion in less than 1 nm micropore of SWCNT and activated carbon. Next, we succeeded in analyzing for adsorption states of nitrogen, water and the hydration structure of zinc ion confined only in the inner pore of SWCNT by controlling the end-cap structure of SWCNTs without any changes in the surface states. Finally, we examined the adsorption phenomena and mechanism of bromide ion inside micropore of microporous carbons.