Simple Preparation of V₂O₅Nanostructures and Their Characterization

Abstract

Low-dimensional nanostructures of vanadium oxides and their derivatives have attracted a great deal of interests due to their novel physicochemical properties and potential applications to high-energy lithium batteries, chemical sensors, nanoresonators, and field effect transistors.1-19 Layerstructured vanadium pentoxide is one of the most studied vanadium oxides despite its low discharge voltages, low electric conductivity, and slow diffusion kinetics of lithium ions.6-13 In order to improve the performance of lithium batteries by employing vanadium pentoxide as a cathode material, a few methods have been used to prepare vanadium pentoxide with better characteristics, which includes the use of aerogels, xerogels, nanocomposites of LiV 2 O 5 with electronically conducting organic polymers and nanostructured materials.9-12 There have been a few recent attempts to develop synthetic methods for nanomaterials of vanadium oxides but preparation of single-crystal vanadate nanostructures still remains challenging. Generally, nanomaterials are prepared in acidic media 2-5 but very few studies report their synthesis using basic media.17 Here, we report synthesis of nanosized vanadium oxides by thermal decomposition of ammonium vanadate nanomaterials prepared via refluxing and precipitation methods in both basic and acidic media. ExperimentalNanosized ammonium vanadates (samples 1, 2, and 3) were synthesized from solutions of vanadium pentoxide dissolved in aqueous ammonium solutions using a few different procedures. Crystallographic information was obtained from X-ray diffraction (XRD) data collected over the 2θ range of 2 to 70 o by a Rigaku D-max-γA powder diffractometer equipped with Cu Kα radiation (λ = 1.54187 Å). Raman spectra were acquired under ambient conditions by using a Bruker IFS/66 Raman spectrophotometer with an Ar + laser operating at 514 nm used as an excitation source. The morphologies of the resulting products were characterized using a FESEM model JSM 6700F field-emission scanning electron microscope. Electrochemical properties of the nanomaterials were investigated in a three-electrode cell with a platinum counter electrode and a silver (Ag) wire pseudo-reference electrode; the working electrode was prepared by first mixing 75% of an active nanostructured material, 20% of carbon black, and 5% of ethylene cellulose and then coating the total mixture of 5.0 mg on the surface of a 1.5 cm 2 ITO glass using a similar technique used for screen printing (V 2 O 5 nanomaterial of 2.5 mg/cm 2 ). A 1.0 M lithium perchlorate solution in propylene carbonate was used as the electrolyte; lithium perchlorate (99.99%, Aldrich) and propylene carbonate (99.7%, Aldrich) were used after recrystallization and distillation, respectively. Cyclic voltammograms (CVs) were recorded at a scan rate of 10 mV/s in a potential limit of −1.0 V and +1.0 V versus a Ag reference electrode using a Zahner IM6 potentiostat/galvanostat. Results and DiscussionThe XRD patterns of the ammonium vanadate and vanadium oxide nanomaterials are sho...

A batch processed titanium–vanadium oxide nanocomposite based solid-state electrochemical sensor for zeptomolar nucleic acid detection

“…52 The peaks labeled in Fig. 2a with their respective indices belong to the orthorhombic V 2 O 5 XRD pattern (JCPDS #001-0359) 53 and characteristic peaks corresponding to any other phases were not observed. This suggested the absence of any secondary vanadium oxide phase within the XRD detection limit.…”

Synthesis of New Mixed-Metal Ammonium Vanadates: Cation Order versus Disorder, and Optical and Photocatalytic Properties

“…The low-temperature removal of small molecules (NH 3 , H 2 O etc.) from metal oxides represents a potentially promising route to prepare new microporous and/or nanostructured materials. , The thermal stabilities and decomposition products of I and II were investigated by heating their powders under flowing nitrogen at a ramping rate of 5 °C per minute. The thermogravimetric results of the weight losses versus temperature are shown in Figure .…”