Simple Preparation of V2O5Nanostructures and Their Characterization

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 sen sors, nanoresonators, and field efbct transistors.1-19Layerstructured 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.6-13In order to improve the performance of lithium batteries by employing vanadium pentoxide as a cathode material, a few methods have been used to prepare vana dium pentoxide with better characteristics, which includes the use of aerogels, xerogels, nanocomposites of LMOs with electronically conducting organic polymers and nano structured materials.9-12There have been a fEw recent attempts to develop synthetic methods for nanomaterials of vanadium oxides but preparation of single-crystal vanadate nanostruc tures still remains challenging.Generally, nanomaterials are prepared in acidic media2-5 but very few studies report their synthesis using basic media.17Here, 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 dis solved in aqueous ammonium solutions using a few different procedures.Sample 1 was synthesized by refluxing a mixed solution of 187 mL of isopropanol and 35 mL of 4.2 M NH4OH aqueous solution, in which 25 g of V2O5 was dis solved.The solution was refluxed in a glass assembly in an oil bath of 70 oC for overnight.The product obtained thereof was then dried in a Petri dish at 60 oC for 48 h.Sample 2 was prepared from a 170 mL of a buffer solution containing 3.53 M NH4F and 1.73 M NH3 (pH = 9), in which 9 g of V2O5 was dissolved (0.30 M).The solution was stirred for 6 h and then placed in an oven at 90 oC for 5 days for evaporation and crystallization.A dense sol was obtained.Sample 3 was synthesized by precipitating from an acidic ammonium