Method of producing a layer of material on a support

A process for preparing a catalyst structure, comprising:

• forming a thermal or diffusion barrier layer on a substrate;
• forming a continuous layer of a catalytic material on a surface of the barrier layer;
• and
• forming the catalyst structure by separating the continuous layer of the catalytic material into droplet-shaped bodies of the catalytic material adhered to the barrier layer;
• wherein:
• the continuous layer of the catalytic material is in the form of a film;
• the surface of the barrier layer has a surface tension lower than a surface tension of the continuous layer of the catalytic material when the continuous layer of the catalytic material is formed on the surface of the barrier layer;
• the catalytic material is a material suitable for catalyzing formation of carbon nanotubes or carbon nanofibers;
• the continuous layer of the catalytic material is formed by making a sequence of deposits of the catalytic material on to the surface of the barrier layer to form continuous sublayers of the catalytic material separated by waiting phases under a vacuum or in a controlled atmosphere;
• and
• the deposits of the catalytic material are made by exposing the substrate to a source of evaporated catalytic material and the waiting phases are carried out by shielding the substrate from the source of evaporated catalytic material.