Hydrothermally synthesised Fe₂O₃ nanoparticles as catalyst precursors for the CVD production of graphitic nanofibres

Graphitic nanofibres (GNFs) have been grown by chemical vapour deposition at 500°C and 700°C, using 6 nm and 20 nm particles of Fe ₂O₃ produced by supercritical water hydrothermal synthesis (scWHS). The morphologies of catalyst and GNFs have been examined using the combined techniques of conventional transmission electron microscopy, high resolution electron microscopy, selected area electron diffraction and powder X-ray diffraction. GNF production varied from well ordered nanofibres with an average diameter of 100 nm, to very large, disordered fibres with diameters ranging from 500 nm to ∼2 νm. Larger fibres were found to have a compound structure composed of discreet domains of graphite and multiwall nanotubes. 20 nm particles produced by scWHS were associated with significant increases in the yield of GNFs as compared with traditional catalyst precipitation routes.