Effect of reduction on graphitization behavior of mesophase pitch-derived carbon fibers

Abstract

Chemically reduced solid-state mesophase pitch carbon fibers below 1000 o C in a flow of hydrogen gas was heat treated up to 3000 o C in an argon atmosphere in order to evaluate the effect of hydrogen on the graphitization behavior. Major phenomena observed during the reduction process are chemical transformation from an ether to a hydroxyl group (corresponding to the rupture of the C-O-C bond) and their subsequent evolution as gases.Finally, oversupplied hydrogen might be utilized to satisfy the dangling bond. For sample heat treated at 3000 o C, the low crystallinity indicates that hydrogen atoms covalently bonded to the end planes of graphitic layers act as an effective barrier to crystallite growth.

Green Synthesis of Electrospun Porous Carbon Nanofibers from Sucrose and Doping of Ag Nanoparticle with Improved Electrical and Electrochemical Properties

“…It is interesting to note here that the decrease in the FWHM for the D band is much higher compared to that of the G band. It has been reported earlier that in presence of reducing atmosphere above 850 °C, the carbonyl and ether groups present at the edge of the crystallites are reduced to hydroxyl groups which are released as gas and water at this high temperature condition leading to formation of smooth grain boundaries . The release of these gases and water also creates porosity in the CNF.…”

“…Subsequently, in presence of hydrogen in the reducing atmosphere used for carbonization, the dangling carbon bonds present at the edge of the planes are satisfied . This homogeneous boundary condition is one of the major reason for decrease in the FWHM of the D‐band peak.…”