Intercalation of formic acid into carbon fibers and their exfoliation

Intercalation of formic acid in a mesophase-pitch-based fibers was successfully carried out by electrolysis in 50% solution. The formation of intercalation compounds was confirmed by X-ray diffraction (XRD), which showed a broad peak at the interlayer spacing of 0.92 nm. By rapid heating of the intercalated compounds of carbon fibers thus produced up to 1000 degreesC, exfoliation was occurred instantaneously. Changes of potential was found to depend on electrolysis temperature to prepare intercalation compounds of carbon fibers with formic acid; at the higher temperature potential saturated at the less electrical charge supplied. Suitable synthesis condition of the intercalation compounds was determined to be the current density of 200 A/g at the electrolysis temperature 10 degreesC. The exfoliation of carbon fibers started at the free end of fibers and proceeds gradually to the fixed end along the fiber axis with increasing charge. This electrolysis behavior suggests that the intercalation of formic acid into the present carbon fibers proceeds from the free end of carbon fibers towards the fixed end with increasing charge. (C) 2002 Elsevier Science B.V All rights reserved.