Coronene was encapsulated in single-walled carbon nanotubes (SWNT) by vapor-phase filling at high (450 °C) and low (385 °C) temperature and by nanoextraction from supercritical carbon dioxide. The presence of coronene inside the tubes was demonstrated indirectly via the formation of double-walled nanotubes (DWNT). To this end several subsequent annealing steps were applied and monitored by Raman spectroscopy. Our results show that the encapsulation is successful with all three methods. However, high-temperature vapor filling produces adsorbed dicoronylene, the dimerized form of coronene, as a side reaction. In order to avoid dicoronylene contamination, we suggest to use low-temperature methods for the production of coronene-filled carbon nanotubes.
Coronene (top) and dicoronylene (bottom) molecules.