Structural analysis of carbon nanofibres grown by the floating catalyst method Original Research Article

Submicron vapour grown carbon fibres (carbon nanofibres) grown by the floating catalyst method (Sample A), using hydrogen sulphide and ammonia to suppress soot formation, have been subjected to a comprehensive structural analysis, by high resolution transmission electron microscopy, PEEL, X-ray diffraction and gas adsorption. Results were compared to those obtained from an industrial sample (Sample B). Both fibres were found to be hollow but with different internal and external diameters. Sample A comprised approximately 90% fibres and 10% soot, which could not easily be separated; the fibres consisting of disordered graphene planes (with the c axis approximately perpendicular to the length of the fibre axis) which became more ordered after heat treatment (2730°C). Sample B consisted of fibres with a complex duplex structure also exhibiting disordered graphene planes; upon heat treatment there was a loss of the duplex structure and an increase in graphitic ordering. The graphitisability was similar for both fibres. Although Sample B had the greater diameter it also displayed the highest BET area.