Properties and Applications

About 30 years ago with the discovery of the football-shaped carbon nanoparticles, called fullerenes, a new development in carbon research began. It will lead to lasting effects on many areas in technology and everyday life. Once their principle of design had been uncovered more variations of the original molecules were developed. As a result of these developments the "elongated" form of fullerenes, called carbon nanotubes (CNTs), were discovered. Beside graphite, diamond, fullerenes and graphene CNTs are a further modification of the element carbon. In addition, CNTs may be one of the most cited nanomaterials.

Due to their unique properties, e.g. CNTs are very stable, and potential applications of CNTs, they are of interest for research and industry. The tensile strength of a multi-walled carbon nanotube was determined to be 63 GPa, which is about 50 times the amount that of steel, but at a much lower weight. Moreover, CNTs may also be electrically insulating, semiconducting or of metallic conductance, depending on the way they are manufactured.


Overview on different carbon nanotube structures: single-walled (SWCNT), double-walled (DWCNT), multi-walled (MWCNT) and possible surface modifications.Overview on different carbon nanotube structures: single-walled (SWCNT), double-walled (DWCNT), multi-walled (MWCNT) and possible surface modifications.

Thus, they might be useful for a wide range of applications. Nearly all industries hope for innovative high-tech applications of CNTs. Examples of such applications are transistors made of nanotubes, nanotube memories, nanotubes to improve plastics and their use in measurement technology. By far, these are not all the fields of applications which may be available. All key industries of our modern societies have possible applications of CNTs or already offer products on the market. For example CNTs are used as additives to various plastics in electronics, in the automotive industry, for lightweight construction or for the production of sports equipment.

CNTs may be useful to contribute in a meaningful manner to the challenges of the "Energiewende" in Germany, the transition from nuclear and fossil-fuel energy to renewable energy. This may be achieved by improving batteries, enforcing rotor blades of wind turbines or by applications in solar- and fuel-cells, but also in construction chemicals to create high performance concrete. These potential fields of application could be ready for use in real products in the immediate future.


The variety of possible applications exhibits a considerable economic potential. Therefore, in Germany a research alliance of more than 90 well-known partners from research and industry had been established in the Innovation Alliance Carbon Nanotubes (2008-2014, Inno.CNT) to focus on the development of CNTs and CNT-derived products. This Alliance, which is endowed with 90 million Euros, is funded 50 % by the federal government.


Carbon nanotubes are divided into two classes, which consist of single-walled CNTs (SWCNT) with a diameter of less than 5 nm on the one hand and multi-walled CNTs (MWCNT) with diameters up to and more than 100 nm on the other hand. Though they are interesting due to their economic opportunities CNTs are also investigated with no direct economic applications in mind. In addition, similar to other carbon nanoparticles, carbon nanotubes have a pronounced tendency to form bunched agglomerates, due to van-der-Waals forces.


Carbon nanotubes are not self-inflammable. Under the influence of an ignition source a mixture of air and carbon nanotubes is explosive (dust explosion). The behaviour in a dust explosion is similar to that of other, carbon-based materials.



Carbon nanotubes can be produced by various methods on the industrial scale. Among these are methods like laser ablation of graphite, the arc discharge between carbon electrodes or chemical vapour deposition (CVD). In CVD hydrocarbons are catalytically decomposed and CNTs can "grow" mainly in parallel on a substrate. In particular it is very important for this method to separate the catalysts from the carbon nanotubes, because otherwise the CNTs cannot be used for all applications mentioned at the start.


Literature arrow down

  1. Wikipedia (EN): Carbon Nanotube (CNT) (last access: November 2014).
  2. Kumar, M et al. (2010), J Nanosci Nanotechnol, 10(6): 3739-3758.


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