Imaging the electronic structure of carbon nanotubes decorated with Fe2O3 nanoparticles

► Carbon nanotubes with Fe2O3 nanoparticles were imaged by scanning transmission X-ray microscopy. ► The results for Fe2O3-out-CNTs revealed the existence of an amorphous carbon coating on CNTs. ► The surface oxidation of Fe2O3-in-CNTs showed a heterogeneous distribution. ► The oxidization of CNTs may favor the internal Fe2O3 decoration of CNTs.