Reactant concentration difference induced microstructure transformation of large-area vapor-grown carbon nanofibers

We explore the effect of mass transport on the microstructure formation of chemical-vapor-deposited carbon nanofibers (CNFs), considering the decrease in carbon source gas concentration along the large-area substrate surface. The microstructures of the CNFs grown along the substrate are transformed from porous, to platelet, to herringbone, and exhibit increased graphite ordering. A model for CNF growth under different reactant concentrations is suggested. The results indicate the critical role of mass transport on the CNF growth mechanism and suggest that adjusting the reactant concentration is an easy way of controlling the CNF microstructures during large-area synthesis. (C) 2013 AIP Publishing LLC.