• PDF / 226,949 Bytes
• 6 Pages / 612 x 792 pts (letter) Page_size
• 38 Downloads / 306 Views

DOWNLOAD

REPORT

---

Vanadium Oxide Nanotubes: Characterization and Electrochemical Behavior Samuel T. Lutta, Arthur Dobley, Katana Ngala, Shoufeng Yang, Peter Y. Zavalij, and M. Stanley Whittingham*

Chemistry Department and the Institute for Materials Research, State University of NewYork at Binghamton, Binghamton, NewYork 13902-6016, U.S.A. ABSTRACT Vanadium oxide nanotubes (VONT) were formed from vanadium (V) oxide and the dodecylamine templating agent by a sol-gel reaction and subsequent hydrothermal treatment. The nanotubes were characterized by transmission electron microscopy (TEM), electron diffraction, thermogravimetric analysis (TGA), infrared spectroscopy and powder X-ray diffraction (XRD). The nanotubes consist of VO2.4 [C12H28N] 0.27 and range in diameter from 100 nm to150 nm. The study further reveals that the compound maintained the tubular morphology when heated at 430o C in an inert atmosphere. However, the tubular morphology is destroyed when the compound is heated at about 130o C in oxygen. Organic free manganese intercalated vanadium oxide nanotubes (MnVONT) were synthesized by an ion exchange reaction. The previously mentioned techniques were used to characterize MnVONT. Mn0.86V7O16+δ. nH2O layers have 2D tetragonal cell with a=6.157(3) Å, while interlayer spacing is 10.52 (3) Å. VONT, heated VONT and Mn0.86V7O16+δ. nH2O are redox – active and can insert lithium reversibly. This study reveals that the electrochemical performance of VONT is enhanced by removing the organic template by heating in an inert atmosphere or exchanging with Mn2+ ions. INTRODUCTION In the course of the present efforts towards miniaturization of electronic and mechanical devices, structures with a size in the nanometer region have stimulated intensive research activities as evidenced in increase in volume of publications in recent past. Among such nanostructures are materials with tubular morphology. Recently transition metal compounds, mainly oxides with two dimensional and three dimensional open structures, have been studied and developed for use as cathode materials in rechargeable secondary lithium battery in our research laboratory [1-3]. Our interest has focused on materials with one-dimensional structures for which the nanotubes are very promising candidates. The tubes attract much scientific interest for electrochemical insertion mainly for two reasons. One, they offer four different contact regions, namely, the inner and outer wall surfaces as well as the tube ends. Secondly, they can provide electrolyte-filled channels for faster transport of the ions to the insertion sites [4]. This study for the first time shows how the electrochemical behavior of the nanotubes can be improved by removing the organic templates by heating under inert atmosphere. *

Contact author; [email protected] V8.3.1

EXPERIMENTAL DETAILS The vanadium oxide nanotubes were prepared according to literature method with modifications where necessary [5]. Vanadium (V) oxide and dodecylamine were mixed in the molar ratio 1:1 in ethanol and the mixture stirre