Method for producing carbon nanotubes attached to a substrate

A method comprising:

• preparing carbon nanotubes, nanofibers or nanofilaments,
• wherein the preparing comprises decomposing at least one carbon precursor in the presence of a catalyst, and
• wherein the preparing further comprises:
• bringing a first gas stream comprising a precursor of a catalyst into contact with a porous substrate so that:
• the first gas stream is at least partially passed through the substrate, or
• the first gas stream is directed on a surface zone of the porous substrate;
• bringing a second gas stream including at least one carbon precursor into contact with said porous substrate;
• and
• heating the porous substrate to a first temperature leading to the deposition of catalyst particles and to the catalytic growth of carbon nanotubes
• wherein the porous substrate is heated locally in a zone through which the first gas stream leaves the substrate, or in the surface zone on which the first gas stream is directed.