Iron surface morphology factor in the growth of filamentous carbon

Abstract

Iron films formed by thermal decomposition of a solution of ferric nitrate in the presence of mercury vapour, with subsequent reduction of the oxide, were found to induce formation of filamentous carbon during the pyrolysis of methane. The same surface prepared in the absence of mercury vapour did not produce filamentous carbon under the same conditions of deposition. Oxidation and reduction of a thin film of sputtered iron also produced a surface on which filamentous carbon was formed from the decomposition of methane, whereas the film of sputtered iron before oxidation gave no carbon filaments. Both the contact with mercury, in the case of iron obtained from ferric nitrate solution, and the oxidation-reduction of the sputtered iron were shown to lead to fragmentation of the surface into particles of a size suitable for growth of filaments rather than other forms of carbon deposit.