A scrolled sheet precursor route to niobium oxide nanotubes

Potassium hexaniobate (K4Nb6O17) is one of the few relatively well-studied oxides which, upon exfoliation, rolls up into scrolls almost quantitatively with monodisperse length (∼300 nm) and diameter (30 nm). The tubes have high surface area (250-300 m2/g) and a wall thickness of 2-3 nm. These H4Nb6O17 scrolls were converted to Nb2O5 via a thermal dehydration process, yielding high surface area (150-200 m2/g) Nb 2O5 nanotubes. Despite extensive atomic rearrangement during dehydration at 400-450°C, little sintering is occurs, and so the tubular morphology is retained. Attempts to conduct further reactions to obtain LiNbO3 and KNbO3 nanotubes from reaction with molten alkali salts failed to yield the intended nanotubular oxides. © 2007 Materials Research Society.