Nitrogen and phosphorus doped single-wall carbon nanotubes

Significant progress in understanding the bonding of phosphorus (P) atoms in single-walled carbon nanotubes was achieved during the NIPHOTUBES project. Although nanotubes possess several exceptional and unique properties, their electronic nature depends on their precise structure. This presents a problem for applications, since nanotubes of a specific type are typically required. Another way to control their properties is by substitutional doping, that is, replacing some carbon atoms with atoms of another element. However, such research has been hampered by the limited availability of doped materials and the difficulty of conclusively identifying the dopant sites. As a highlight of the project, we made a pioneering study on measuring the bonding of phosphorus in carefully purified samples confirming its feasibility as a dopant, and were further able to directly image a single P dopant in graphene. Finally, although not part of the original project goals, our finding that an electron beam could be used to move dopant atoms controllably in the graphene lattice may prove to be a major discovery, contributing to pushing the limits of what is technologically possible in science.