Precursor morphology controlled formation of rutile VO2 nanorods and their self-assembled structure

Rutile VO2 nanorods have been synthesized by the precursor morphology controlled formation. The precursor single-crystal VO2 hydrate nanorods have been obtained via the hydrothermal reaction of KOH, V2O5, and hydrazine in a sealed autoclave at low temperature. The reducing agent N2H4 plays a key role in the control of one-dimensional morphology. According to the data of differential scanning calorimetry and thermogravimetric analysis, rutile VO2 nanorods have been formed when the precursor VO2 hydrate is heated at 340 degreesC for 1 day in flowing N-2 and maintaining the morphology of the precursor. The products have been characterized by means of X-ray powder diffraction, transmission electron microscopy, high-resolution electron microscopy, selected area electron diffraction, and X-ray energy-dispersive spectroscopy techniques. It is shown that these rutile VO2 nanorods are self-assembled by VO2 nanocrystalline domains with the same crystallographic direction along the rod axis. The reaction details and features are described and discussed.