Abstract: The substrate pre-treatment plays a key role in obtaining hollow-cored carbon nanotubes (CNTs) and solidcored carbon nanofibers (CNFs) from flames. This paper introduces a simply and high-efficient process by coating a NiSO4 or FeSO4 layer on the substrate as catalyst precursors. Comparing with the regular pretreatment methods, the present experiments showed that the coating pre-treatment provided the following advantages: 1) greatly shortening the synthesis time; 2) available variant substrates and carbon sources; 3) narrowing the diameters distribution. The sulfate is considered to be a crucial factor at the growth of CNTs and CNFs, because it increases the surface energy of catalyst particles and the surface specificity of sulfurs action in metallic grains. This novel process provides a possibility for high quality and mass production of CNTs and CNFs from flames.

Key words: Carbon nanotubes, Carbon nanofibers, Flames, Sulfate