The use of transmission electron microscopy tomography to correlate copper catalyst particle morphology with carbon fiber morphology

In this study carbon fibers of various morphologies have been synthesized by the decomposition of acetylene over copper supported catalysts (Cu(NO3)(2)/TiO2, at 250 degrees C). In order to investigate the relationship between the morphologies of the copper catalyst particle and that of the carbon fiber extruded, tilting procedures (+/- 60 A axis and +/- 30 B axis) under TEM (120 kV) were performed. In this way a 3-D (rather than a 2-D) image of the Cu crystallites were obtained which permitted for the 3-D shape of the Cu catalyst particle to be linked to the morphology of the extruded carbon fiber. Whereby copper particles that give distorted decahedra are apt to form helical fibers, trigonal bi-pyramidal particles give linear fibers. Various plate-like particles were also investigated, and it was observed that as the number of sides varied (3, 4, 5 or 6) there was a corresponding change in the carbon fiber helicity. Herein we report on our findings that reveal the geometric structures involved in controlling the shape of morphologically diverse carbon coils, illustrating the influential role catalyst particle shape plays in carbon fiber synthesis. (C) 2011 Elsevier Ltd. All rights reserved.