Square-nanosheet flowers with an ammonium vanadate phase and their transformation to VO2(B) net-like nanosheets

We report special square-nanosheet flowers with an ammonium vanadate phase, which are synthesised by choosing an appropriate solvent system (ethanol aqueous solution) and reductant (octadecylamine (ODA)) under solvothermal conditions. For the synthesis mechanism, a reduction reaction (phase transformation) takes place, where the raw material, NH4VO3, transforms to an intermediate, NH4V3O8, and then to the target ammonium vanadate phase. The ethanol aqueous solvent promotes the oriented growth of the two-dimensional crystal. ODA serves as the reductant and is responsible for the low vanadium valence in the product. By treating these new ammonium vanadate flowers during the hydrothermal reaction, the growth of VO2(B) net-like nanosheets can be realised. To the best of our knowledge, there is no information available on this ammonium vanadate nanostructure and its transformation into VO2(B). This new ammonium vanadate two-dimensional assembly material can be applied as an anode material for the Li-ion batteries and exhibits a reversible electrochemical capacity of 817 mhA g−1 after 130 cycles at 1 A g−1, as well as a good rate performance. The findings in this study have important implications for the synthesis and application of ammonium vanadate and vanadium oxide bronze nanostructures.