Synthesis, Characterization And Catalytic Properties Of Vanadium Oxide Nanomaterials

Preparation of nanomaterials with novel morphology and excellent properties has become one of the research hotspots. Several nanomaterials, such as composite oxide composed of vanadium bronzes and volborthite, intermediate phase V10O24·12H₂O and vanadium pentoxide, cadmium sulfide, were successfully fabricated based on a facile hydrothermal or hydro/solvothermal method. The obtained products were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared (FT-IR) spectrophotometer and ultraviolet-visible (UV-vis),energy-dispersive X-ray fluorescence spectroscopy (EDXS),high-resolution transmission electron microscopy (HRTEM), fluorescence spectrophotometer and X-ray photoelectron spectroscopy (XPS). The main results are shown below:(1) Copper vanadium composite oxides with a novel"flower"and"fruit"morphology composed of Cu0.85V₂O₅ and Cu₃V₂O₇(OH)2·2H₂O have been successfully prepared by a simple hydrothermal method using citric acid as capping reagent. The molar ratio of precursors and reaction time were found to have great impact on both the morphology and composition of the resulting materials. The composite shows a strong catalytic ability in the degradation of methylene blue (MB), with a degradability as high as 83.6% in 5 min, and great reusability and recyclability as well. Many reaction factors, such as oxygen, catalyst dosage, MB concentration, pH, temperature and composition of the catalyst are proved to play significant roles in the degradation process.(2) Monoclinic V10O24·12H₂O nanostructures with netted sphere-like morphology were successfully prepared via a simple hydrothermal route, using commercial V₂O₅ as precursor and polymer polyvinyl pyrrolidone (PVP) as surfactant in a hydrogen peroxide aqueous solution at 120℃for 12 h. They can be transformed to tetragonal V₂O₅ nanoparticles by oxidation in atmosphere in Muffle at 450℃for 3h. The possible growth mechanism was discussed through time-dependent experiments. Moreover, their electrochemical properties were evaluated by cyclic voltammogram (CV) and their catalytic abilities were investigated by photodegradation experiments.(3) Hexagonal nanorod-based flower-like CdS nanocrystals were synthesized using sulfur and cadmium acetate as precursors via a simple hydro/solvothermal method at 180℃for 12 h in a binary water-ethylene glycol (EG) system. The influences of temperature, time, concentration of EG and molar ratio of precursors on the morphology were investigated. The possible growth mechanism was also discussed, and its catalytic ability was evaluated.