Résumé
Carbon nanotubes (CNT) were synthesized from a H2–CH4 mixture with W/Co–MgO catalystby a catalytic chemical vapour deposition (CCVD) method. Different W/Co ratios wereinvestigated. From transmission electron microscopy observations, we observed that boththe number of walls and the diameter of CNT increased with the proportion of tungsten. Apromoter effect was observed as long as the proportion of tungsten was kept low and CNTwith a number of walls ranging from 2 to 5 were obtained. With a higher proportion oftungsten, multi-walled carbon nanotubes (MWNT) up to 10 walls were synthesised,together with additional undesirable carbon nanofibres.