Method for preparing metal-free nitrogen-containing carbon nanotubes

The present invention relates to a method for preparing metal-free nitrogen-containing carbon nanotubes (NCNTs) having a core/shell structure, in which the core is composed of carbon and the shell is mainly composed of carbon and nitrogen. The invention also relates to metal-free nitrogen-containing carbon nanotubes (NCNTs) obtainable by said method and to their use as a catalyst for oxygen reduction reactions, notably in alkaline media in fuel cells.