Synthesis of reduced vanadium oxides in aqueous solutions
Reduction of aqueous sodium and potassium vanadates with aqueous ABH4 (A=Na and K) at ambient temperatures has been investigated systematically to obtain reduced vanadium oxides. Although the as-prepared samples do not show any discernible diffraction peaks, several binary crystalline oxides such as V2O3 , V3O5 , VO2 , and V6O13 , as well as ternary oxides such as Na0.33V2O5 , K0.23V2O5 , and K2V3O8 could be identified after annealing in evacuated sealed silica tubes at 580 °C. The volume and concentration of borohydrides as well as the reaction pH are found to influence the nature of the reaction products. Selected area diffraction of the as-prepared samples in transmission electron microscopy (TEM) indicates that they are nanocrystalline.