HYDROGEN STORAGE IN CARBON NANOFIBRES FOR DEFENCE APPLICATIONS: THE INFLUENCE OF GROWTH PARAMETERS ON GRAPHITIC QUALITY AND STORAGE CAPACITY

摘要

Carbon nanofibres were synthesised using Fe:Ni:Cu and Fe:Ni catalysts. Fibrecharacterisation by Raman spectroscopy and Transmission Electron Microscopy hasaided the optimisation of the process to produce highly graphitic nanofibres. Theprocess window for reproducible fabrication of these structures is narrow and theprocess requires good heat exchange between the catalyst and gases combined with onlinemonitoring of the process. Hydrogen storage experiments were performed at 120bar, using a bespoke apparatus with differential pressure measurement. In the light ofrecent controversies on the reliability and accuracy of hydrogen storage measurements,a detailed error analysis has been performed on the uptake measurement system. Atpresent a maximum uptake of 4.2 wt % has been achieved for as-prepared nanofibres,increasing to over 6.5 wt % following heat-treatment in Ar at 1000°C.