Synthesis of morphology-controlled niobium oxide nanorods array

Morphology-controlled niobium oxide nanorods array were successfully prepared in a mixed NH₄F and H₂O₂ solution by using niobium powder as the starting materials via hydrothermal method. The morphology and composition of niobium oxide film were characterized by X-ray diffraction patterns(XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), respectively. The reaction time and hydrothermal temperature and concentration of NH₄F, which affect the final composition and morphology of niobium oxide films, were also investigated in details. The results show that niobium oxide crystal have a strong anisotropy growth in the presence of NH₄F and H₂O₂, which guides the oriented growth of hexagonal nanorods array on the niobium powder surface. The concentration of NH₄F play great roles in the formation of the final products, the morphological of niobium oxide film is transformed from polyhedron granule to circular nanorods array and aggregated nanoparticles with the increase of NH₄F concentration. Niobium oxide nanorods arrays can be obtained at Nb substrate after hythermal reaction at 150°C for 10 h with adding 0.5 g NH₄F. A formation mechanism is also proposed.