Ordered Construction, Mechanism And Properties Of Vanadium Oxide Nanowires

Vanadium is a typical multi-valence transition metal element, which can form different types of vanadium oxides. Due to its unique and excellent properties, One-dimensional vanadium oxide nano-materials have gained an increasing attention in many areas. In this thesis, by using rheological self-assembled method, we synthesized the nanowires with different morphologies, such as the bundle-like VO2 nanowires arrays. Besides, the LB technique was used to construct the nanowires in order. The content of the article reads as follows:1. V3O7·H2O nanowires were synthesized via a rheological self-assembled method, and by annealing the as-synthesized V3O7·H2O nanowires at 400℃in air, V2O5 nanowires were obtained. Then the peoducts were functionalized with cetyltrimethyl ammoniumbromide. Finally, through LB assembly, locally-ordered nanowire arrays were obtained. The structure of the VO2 nanowire monolayers was characterized via viawide-angle XRD, UV-vis, SEM. Using LB technique, nanowire films were deposited on aluminum foil and used as electrode for lithium ion batteries. Electrochemical properties were analyzed, and the results illustrated that the locally-ordered nanowire film provided a better and more orderly way for Li+ion diffusion.2. VO2 nanowires were synthesized via a rheological self-assembled method, they were functionalized with stearic acid and cetyltrimethyl ammoniumbromide, then locally-ordered nanowire arrays were obtained by LB assembly. The structure of the VO2 nanowire monolayer was characterized by using XRD, SEM and other methods. Besides, we also studied the electrochemical properties. CV investigation confirmed that electrochemical capacity of VO2 nanowires could be enhanced about two orders of magnitudes through LB assembly. I-Ⅴinvestigation showed the conductivity could be improved by about two orders of magnitudes. By analyzing the mechanism of the Li+ion insertion/extraction along VO2 nanowires before and after LB assembly, the improvement of electroactivity of VO2 nanowires may result from the orientated, locally ordered structure and the increased surface areas.3. Bundle-like VO2 nanowire arrays were synthesized via the rheological self-assembled method, The structure of the products were characterized by using XRD, SEM. The formation mechanism of bundle-like VO2 nanowire arrays was proposed, and the electrochemical properties of products were tested. The results show that the charge/discharge capacities of the first cycle are realtivley high, but the cycling ability need to be improved. It is also shown that the electrochemical properties of the bundle-like VO2 nanowire arrays are related to the orderliness and stability of the special structure.