Vanadium pent-oxide gel has been kn

Vanadium pent-oxide gel has been known for more than one century. Many syntheses of vanadium pent-oxide sol or gel have already been reported in literature. This sol can be prepared by pouring the mixture from the reaction of the heated ammonium vanadate with hot nitric acid or hydrochloric acid into water. V2O5 sols have also been obtained via the thermo-hydrolysis of aqueous solutions of VOCl3 or the hydrolysis and condensation vanadium alkoxides VO(OR)3 (R ¼ Bu, t-Am). It can also be made directly from the oxide. Hydrogen peroxide, for instance, reacts vigorously with crystalline V2O5, giving rise to a red gelatinous product. Muller obtained vanadium pent-oxide gels simply by pouring the molten oxide heated around800 C into water [31]. Large quantities of these gels are nowadays prepared this way for industrial purposes. However, the concentration of vanadium is difficult to adjust in these processes.
In this paper, a novel route which was the combination of sol– gel and hydrothermal treatment processes for the synthesis of nano-sized VO2(R) was carried out. A new vanadium source which is vanadium pent-oxide gel obtained from the reaction of V2O5 and H2O2 was innovatively adopted in hydrothermal process. High performance spherical rutile VO2 or doped VO2 particles could be prepared by reduction this vanadium source with N2H4 then followed by hydrothermal treatment. Using the prepared nano-particles, the composite film with nice comprehensive performance comparable with single-layer PVD film could be obtained successfully.