Tailoring Physicochemical Properties of V2O5 Nanostructures: Influence of Solvent Type in Sol-Gel Synthesis

The influence of different solvents, including aqueous and nonaqueous types, on the physicochemical properties of V2O5 nanostructures was thoroughly investigated. Various characterization techniques, such as XRD, XPS, FTIR, Raman spectroscopy, UV-vis DRS, SEM, TEM, and BET, were employed to analyze the obtained materials. Additionally, the adsorption properties of the synthesized V2O5 nanostructures for methylene blue were examined, and kinetic parameters of adsorption were calculated. The results demonstrate that the morphology of the obtained crystals can be finely controlled by manipulating water concentration in the solution, showcasing its profound impact on both the structural characteristics and adsorption properties of the nanostructures. Furthermore, the structural changes of the resulting V2O5 material induced by solvents show strong impacts on its photocatalytic properties, making it a promising photocatalyst.

Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries

The mixing of [V10 O28 ]6- decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V2 O5 (gem-V2 O5 ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2 O5 consisting of very small crystallites (TBA-V2 O5 ). Electrochemical analysis of the materials' performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem-V2 O5 cathode deliver higher initial capacity and superior capacity retention than TBA-V2 O5 . The smaller crystallite size and higher surface area of TBA-V2 O5 allow faster lithium insertion and superior rate performance to gem-V2 O5 .

The valance state of vanadium-key factor in the flexibility of potassium vanadates structure as cathode materials in Li-ion batteries

Potassium hexavanadate (K₂V₆O₁₆·nH₂O) nanobelts have been synthesized by the LPE-IonEx method, which is dedicated to synthesis of transition metal oxide bronzes with controlled morphology and structure. The electrochemical performance of K₂V₆O₁₆·nH₂O as a cathode material for lithium-ion batteries has been evaluated. The KVO nanobelts demonstrated a high discharge capacity of 260 mAh g⁻¹, and long-term cyclic stability up to 100 cycles at 1 A g⁻¹. The effect of the vanadium valence state and unusual construction of the nanobelts, composed of crystalline and amorphous domains arranged alternately were also discussed in this work. The ex-situ measurements of discharged electrode materials by XRD, MP-AES, XAS and XPS show that during the subsequent charge/discharge cycle the potassium in the K₂V₆O₁₆·nH₂O structure are replacing by lithium. The structural stability of the potassium hexavandate during cycling depends on the initial vanadium valence state on the sample surface and the presence of the “fringe free” domains in the K₂V₆O₁₆·nH₂O nanobelts.

The Impact of the Vanadium Oxide Addition on the Physicochemical Performance Stability and Intercalation of Lithium Ions of the TiO2-rGO-electrode in Lithium Ion Batteries

This work determines the effect of the addition of various amounts of vanadium oxide on the work of a cell built from a hybrid V_xO_y-TiO₂-rGO system in a lithium-ion cell. Moreover, a new method based on solvothermal chemistry is proposed for the creation of a new type of composite material combining reduced graphene, vanadium oxide and crystalline anatase. The satisfactory electrochemical properties of VxOy-TiO₂-rGO hybrids can be attributed to the perfect matching of the morphology and structure of VxOy-TiO₂ and rGO. In addition, it is also responsible for the partial transfer of electrons from rGO to VxOy-TiO₂, which increases the synergistic interaction of the VxOy-TiO₂-rGO hybrid to the reversible storage of lithium. In addition a full cell was created LiFePO₄/V_xO_y-TiO₂-rGO. The cell showed good cyclability while providing a capacity of 120 mAh g⁻¹.

Complimentary effects of annealing temperature on optimal tuning of functionalized carbon–V2O5 hybrid nanobelts for targeted dual applications in electrochromic and supercapacitor devices

Herein, carbon nanosphere-decorated vanadium pentoxide (C@V₂O₅) hybrid nanobelts were grown via a single step hydrothermal route with improved electronic conductivity as compared to that of pristine oxide. This hybrid nanomaterial exhibits different complimentary ranges of optimum post-growth annealing temperatures, which are suitable for dual applications either in electro-chromic smart windows or in supercapacitors. C@V₂O₅ nanobelts annealed at 350 °C appear to favor electro-chromic applications. They exhibit maximum dynamic optical transmission modulation as they switch from yellow to dark green, fast switching response, and high visible transmittance. In contrast, C@V₂O₅nanobelts annealed at 250 °C have been found to be most suitable for supercapacitor applications. They display a high specific capacity and an enhanced diffusion coefficient. Moreover, they exhibit long lifetimes with a capacity retention of ∼94% even after 5000 cycles of operation. Therefore, the obtained results clearly indicate that optimization of the post-growth annealing temperatures is very important and rather complementary in nature in terms of determining the most favorable device functionalities. It enables us to optimally tune these hybrid nanomaterials for targeted, device-specific, energy applications in either electrochromic or supercapacitor technologies simply based on the annealing temperature alone.

Herein, carbon nanosphere-decorated vanadium pentoxide (C@V₂O₅) hybrid nanobelts were grown via a single step hydrothermal route with improved electronic conductivity as compared to that of pristine oxide.

Magnetic Fe3O4@V2O5/rGO nanocomposite as a recyclable photocatalyst for dye molecules degradation under direct sunlight irradiation

Reduced graphene oxide nanosheets decorated with Fe₃O₄ and V₂O₅ nanoparticles as a magnetically recoverable nanocomposite (Fe₃O₄@V₂O₅/rGO) was synthesized by a simple solution chemistry approach. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR), fluorescence, and zeta potential measurements. The narrow band gap and different band gap energies of Fe₃O₄ and V₂O₅ proved to be suitable for the absorption of visible light in the solar spectrum. The Fe₃O₄@V₂O₅/rGO displayed indeed excellent photocatalytic activity towards the degradation of harmful cationic Bismarck Brown (BB) as well as anionic Acid Orange 7 (AO) dyes under direct sunlight irradiation. The photocatalytic activity of the Fe₃O₄@V₂O₅/rGO is influenced by solution pH, catalyst loading, initial dye concentration and the presence of different inorganic ions (NH₄⁺, Na⁺, Mg²⁺, Ca^2+, SO₄^2-, Br^-, NO₃^-, Cl^-, HCO₃^-). This study provides a new scientific knowledge on the sunlight driven photocatalytic degradation of dye molecules using novel mixed metal oxide/rGO nanocomposite photocatalyst.

Enhanced lithium storage performance of V2O5 with oxygen vacancy

Orthorhombic phase V₂O₅ nanosheets with a high V⁴⁺ content (V-V₂O₅) have been fabricated via a facile sol–gel method and freeze-drying technology followed with a vacuum annealing process.