Synthesis And Properties Of One-dimensional Vanadium Oxide Nanoarrays

Due to their surprising physical and chemical properties, nanomaterials have great potential applications in catalyst, filtrating light, light absorption, medicine, magnetism media. At the same time, nanomaterials will also promote the development of the foundational researches. Polycarbonate (PC) membrane contains uniform parallel pores and high pore density, and can be removed through pyrolysis and oxidation. One-dimensional nanomaterial synthesized by PC template has attracted many researchers and has been studied deeply in recent years. Firstly this thesis summarized the newest progress of using PC template to prepare functional nanomaterials. On this base, we prepared vanadium oxide nanoarrays by combining sol-gel and template methods. The main results and conclusions can be summarized as follows:The structural characters of V₂O₅ and its hydrate V₂O₅·nH₂O were analyzed as follows, layered structure good for intercalation. So they can be intercalated by mobile guest species (atoms, molecules, or ions) into crystalline host lattices to form many promising intercalation compound materials. What's more, V₂O₅ sols were fabricated by two methods, which were melt quenching method and reaction between H₂O₂ and V₂O₅ powder, respectively. Different sols from such two methods were analyzed and compared in concentration and stability. And it can be found that sols from melt quenching method had better stability, however, sols from the other method had higher concentration.Vanadium oxide nanotube and nanorod arrays were synthesized via template-based physical wetting of V₂O₅ sols from melt quenching and reaction between H₂O₂ and V₂O₅ powder, respectively. PC membranes were chose as templates. EDS patterns of the nanotubes and nanorods showed their composition of the vanadium oxide. TEM and SEM images of the products showed clear hollow structure of nanotubes with uniform outer diameter and inner diameter and clear solid structure of nanorods with uniform diameter, forming ordered arrays, respectively. XRD patterns and HRTEM images of the as-synthesized products indicated the nanotubes corresponding to monoclinic V₂O₅·3H₂O nanocrystals, but nanorods corresponding to the composition of monoclinic V₂O₅·3H₂O crystals and V₂O₅·H₂O crystals. And corresponding HRTEM images indicated nanorods corresponding to monoclinic V₂O₅·3H₂O crystals. Capillary effect, pressure difference resulting from vacuum pumping, electronegativity of PC membrane pore walls and electropositivity of V₂O₅ sol particles caused sol particles to be adsorbed to the pore walls of the temple and resulted in the formation of vanadium oxide nanotubes, which showed the successful fabricating of vanadium oxide nanotube arrays. Moreover, times of vacuum pumping increasing, different adsorption and contact between PC membrane pore walls and V₂O₅ sols from reaction between H₂O₂ and V₂O₅ powder caused the formation of vanadium oxide nanorods, which showed the successful fabricating of vanadium oxide nanorod arrays. Ultraviolet visible light transmitted spectrum of the nanotubes was corresponded with the intrinsic long wavelengthedge of vanadium oxide nanotubes. In addition, because of the quantum size effect and superficial effect, the optical absorption edge of vanadium oxide nanotubes shifted to short wavelength direction. FE behaviors testing indicated that vanadium oxide nanotube arrays had good FE properties: low turn-on voltage and high maximum current, which made the as-synthesized products a promising candidate for FE emitters. Similarly, because of the quantum size effect and superficial effect, the optical absorption edge of vanadium oxide nanorods also shifted to short wavelength direction. FE behaviors testing indicated that vanadium oxide nanorod arrays also had good FE properties.