Carbon nanotube growth on a swellable clay matrix

The successful growth of multiwalled carbon nanotubes on montmorillonite surfaces has been attained via chemical vapor deposition of acetylene and studied by means of electron microscopy, XRD, Mossbauer spectroscopy, and thermal analysis measurements. Clay surfaces loaded with different amounts and types of metal salt catalyst precursors, namely FeCl3 center dot 6H(2)O, Fe(NO3)(3)center dot 9H(2)O, Ni(NO3)(2)center dot 6H(2)O, and Co(NO3)(2)center dot 6H(2)O, afforded clay-carbon nanotube composite products with varying carbon nanotube content and quality. The anion of the metal salt controls the hydrolysis during metal deposition on the clay surfaces and affects the transition to metal carbides at the final step of carbon deposition. Replacement of iron chloride by iron nitrate induced a minimum content of carbide impurities in the final product; nickel nitrate proved to be the best catalyst for nanotube growth, greatly improving their quality. Finally, the optimum time for carbon deposition at 700 degrees C and catalyst loading were elaborated in order to receive clay-carbon nanotube composites combining a high quality and appropriate content of carbon nanotube with the swelling, intercalation, and ion exchange properties of the parent mineral.