Nanoengineering with residual catalyst from CNT templates

We investigate how residual catalyst from carbon nanotube (CNT) templates can be used to engineer novel functional nanomaterials. CNTs, produced via continuous flow chemical vapour deposition, typically contain catalyst residues in the form of encapsulated metal clusters or of iron oxide nanoparticles attached to the outside of the CNTs. These CNTs are used as sacrificial templates for TiO2 coatings using benzyl alcohol as a linking agent. Upon oxidation of the CNTs, the encapsulated iron particles dissolve into the TiO2 lattice and form iron-doped TiO2 nanotubes without the formation of secondary phases, while the iron oxide particles merely attach to the outer surface. The materials show extended light absorption into the visible range, a requirement for visible-light photocatalyst.