Hydrothermal Synthesis of Novel Vanadium Oxides

Abstract

Extending our prior work on tungsten and molybdenum oxides, we have found that a wide variety of vanadium oxides can be prepared using hydrothermal methods. These include a number of layer compounds as well as cluster complexes. The starting reaction medium usually contained vanadium pentoxide, an alkali containing compound such as LiOH, an organic template such as tetramethylammonium, and the pH of the whole was controlled by the addition of acid. Reaction temperature was 150°C to 200°C, and time was up to 3 days. A new lithium vanadium oxide, which has the simplest structure of any layered vanadium oxide, was formed. The lithium could be readily removed leading to a new form of vanadium dioxide. This vanadium oxide was also capable of intercalating a variety of other ionic and molecular species. Several other new vanadium oxides containing the TMA cation were also formed; one of these TMAV3O7 readily absorbed oxygen to form TMAV3O8. Addition of zinc or iron to the reaction medium caused the formation of layer structures containing double V2O5 layers; for iron the TMA was retained in the structure whereas for zinc the TMA was excluded. Changing the organic entity resulted in other new structures, for example methylamine and dimethylamine gave tetragonal structures.

Electrochemical–hydrothermal synthesis and structure determination of a novel layered mixed-valence oxide: BaV7O16·nH2O

“…For example, the pH has been shown to play a critical role in determining the final products of hydrothermal synthesis of vanadium oxides in reactions containing tetramethylammonium cations. 13 At present, we are investigating whether a modification of conventional hydrothermal synthesis in which one of the metal ion reactants is electrochemically introduced can provide better control over product formation. Previous studies of the hydrothermal electrosynthesis of thin films of BaTiO 3 and SrTiO 3 have been reported but the technique has not been used specifically for the synthesis of new compounds.…”

Critical review of the recent progress and challenges of polyanion Na3V2(PO4)3 cathode materials in rechargeable sodium-ion batteries

“…Hydrothermal/solvothermal synthesis is one of the most common one-pot synthesis techniques used to prepare a wide range of transition metal oxides and phosphates. [89][90][91] In 2014, Duan et al synthesized a core-shell NVP@C nanocomposite through the combination of the hydrothermal and sol-gel methods. 92 The particle growth and conductive carbon coating were determined by ascorbic acid and polyethylene glycol 400.…”

Magnetic Properties of Vanadium Oxide Nanotubes, Nanourchins, and Nanorods.

“…In the past two decades vanadium oxides and subsequent intercalates have received much attention because of their possible secondary cathode and oxidative catalysis applications [1,2]. Vanadium oxides show a very rich crystal chemistry due to diversity of vanadium oxidation states (3+, 4+, and 5+) and oxygen coordination, which changes from octahedral to square pyramidal and tetrahedral with the increase of vanadium oxidation state [1].…”

“…Vanadium oxides show a very rich crystal chemistry due to diversity of vanadium oxidation states (3+, 4+, and 5+) and oxygen coordination, which changes from octahedral to square pyramidal and tetrahedral with the increase of vanadium oxidation state [1]. This allows for the formation of many layered and open-framework compounds, which makes them prospective materials for ion intercalation, exchange and electrical energy storage [1,3].…”