Novel nanotubes made of more than one type of atom
Extensive research has been focused within the last few decades on carbon nanotubes (NTs), long and narrow needle-like structures with the highest strength-to-weight ratio of any substance known and interesting electrical properties as well. The nearly limitless list of current and potential applications includes those in medicine, aerospace and electronics. Obstacles to widespread practical integration of NTs include complicated and costly production processes as well as practical length limits (far less than that theoretically possible). European researchers sought to develop novel synthesis methods for producing three-dimensional (3D) NTs consisting of combinations of carbon (C), boron (B) and nitrogen (N) (heteroatomic) via funding of the ‘Novel, heteroatomic boron, nitrogen and carbon nanotubes’ (BNC TUBES) project. In particular, investigators set out to develop synthesis and characterisation techniques enabling atomic-level descriptions of NT formation mechanisms, NT structures and properties leading to the design of highly transparent and conductive flexible thin NT mats. Researchers sought inspiration from chemical vapour deposition (CVD) and laser evaporation methods for producing carbon NTs as well as the carbon NT substitution reaction for producing heteroatomic NTs including single-, double- and multi-walled NTs (SWNTs, DWNTs and MWNTs, respectively). In fact, BNC TUBES investigators successfully produced and characterised B-, N-, and BN-doped carbon SWNTs and MWNTs with well defined and well controlled formation mechanisms, structures and properties including length and defect concentrations as well as optical absorption and electrical conductivity. Detailed analyses elucidated advantages and disadvantages of the various synthesis methods as well as of the various doping combinations. BNC TUBES project results have important implications for a rapidly emerging market on the threshold of development of novel electronic devices based on carbon NT technology. Exploitation of project outcomes could have positive impact on the competitive position of the EU in a potentially huge global market.