Tailoring the electronic properties of single-walled carbon nanotubes via filling with nickel acetylacetonate

Although chemical functionalization of single-walled carbon nanotubes was extensively studied, in many cases detailed information about the influence of the nanotube metallicity and diameter is missing. Here, we present an X-ray photoemission and absorption spectroscopy study of endohedrally functionalized carbon nanotubes with different diameters, where Ni(II) acetylacetonate molecules are reacted to tailor the nanotubes' electronic properties. The filling factor is found to be dependent on the SWCNT base material used. We trace the reaction process of the filling material at several annealing steps and reveal their dependence on annealing temperature, which allows doping of nanotubes to be controlled.