Research on the Response Characteristics of Vanadium Pentoxide Film to the Irradiation of Ultrafast Pulsed Laser

Vanadium pentoxide (V2O5) is the most stable phase among many transition metal vanadium oxides, and has already been widely used in many fields. In this study, the morphological, structural, and optical responses of V2O5 film to ultrafast laser irradiation was investigated. The third-order nonlinear optical properties of V2O5 film were measured by common Z-scan technique, and the results showed that V2O5 film has self-defocusing and saturable absorption characteristics. The third-order nonlinear absorption coefficient and nonlinear refractive index were calculated to be -338 cm/GW and -3.62 × 10-12 cm2/W, respectively. The tunable saturated absorption with modulation depth ranging from 13.8% to 29.3% was realized through controlling the thickness of vanadium pentoxide film. V2O5 film was irradiated by ultrafast laser with variable pulse energy, and the morphological and structural responses of the V2O5 to the laser with different energy densities were investigated. The irreversible morphological and structural responses of V2O5 films to ultrafast laser irradiation was analyzed using the phase-contrast microscope and Raman spectrum. The chemical structure change from V2O5 to V6O13 was considered the main reason for refractive index modification.

Investigation on CH4 sensing characteristics of hierarchical V2O5 nanoflowers operated at relatively low temperature using chemiresistive approach

Methane (CH₄) gas, the second most potent greenhouse gas share a substantial role in contributing to the global warming and it is a necessary pre-requisite to detect the release of CH₄ into the environment at its early stage to combat climate change. In that front, this work is focussed to develop an effective CH₄ gas sensor using vanadium pentoxide (V₂O₅) thin films that works at an operating temperature of ∼100 °C. To understand the effect of sputtering power towards the structural characteristics of V₂O₅ films, X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) analysis were performed from which the orthorhombic polycrystalline structure of V₂O₅ thin films was confirmed with varied texture co-efficient. Further, the surface elemental studies using X-ray photoelectron spectroscopy (XPS) confirmed the prominence of V⁺⁵ oxidation state from the binding energy of V2p_3/2 and O1s peak. The effect of sputtering power on the growth of different nanostructures were observed using field-emission scanning electron microscopy (FE-SEM). The critical role of adsorption and desorption kinetics of the deposited nanostructures were explained through first order kinetics based on Elovich model and the phase stability of different nanostructures were evaluated using Raman spectral analysis. This work achieved the sensor response of about ∼8% towards CH₄ at an operating temperature of 100 °C towards 50 ppm concentration.

Anti-angiogenic vanadium pentoxide nanoparticles for the treatment of melanoma and their in vivo toxicity study

In recent days, vanadium complexes and nanoparticles have received sustainable attention owing to their vast applications in different fields. In the present study, we report a facile approach for the synthesis of irregular dumbbell shaped vanadium pentoxide nanoparticles (V₂O₅ NPs: 30-60 nm) via the polyol-induced microwave irradiation process along with calcination. The as-synthesized nanoparticles were characterized using various physico-chemical techniques (e.g. XRD, TEM, FT-IR, DLS and XPS). The cell viability assay showed that V₂O₅ NPs could efficiently inhibit the proliferation of different cancer cells (B16F10, A549, and PANC1), depicting their anti-proliferative activity. However, V₂O₅ NPs did not exert significant cytotoxicity to the normal cells (CHO, HEK-293 and NRK-49F), suggesting their biocompatible nature. Interestingly, these nanoparticles inhibited the proliferation and migration of the endothelial cells (HUVECs and EA.hy926) and disrupted the blood vasculature in a chick embryo model, indicating their anti-angiogenic properties. The mechanistic study revealed that the effective internalization of V₂O₅ NPs generated intracellular reactive oxygen species (ROS) which in turn up-regulated p53 protein and down-regulated survivin protein in cancer cells, leading to the apoptosis process. Furthermore, the administration of V₂O₅ NPs to melanoma bearing C57BL6/J mice significantly increased their survivability as compared to the control untreated tumor bearing mice, exhibiting the therapeutic potential of the nanoparticles against melanoma. Additionally, the in vivo toxicity study demonstrated no toxic effect in mice upon sub-chronic exposure to V₂O₅ NPs. Altogether, we strongly believe that V₂O₅ NPs could intrinsically provide a new direction for alternative therapeutic treatment strategies for melanoma and other cancers by employing their anti-angiogenic properties in the future.

Synthesis and trimethylamine sensing properties of spherical V2O5 hierarchical structures

Spherical V₂O₅ hierarchical structures assembled from nanosheets exhibit rapid response/recovery speeds to TMA gas.

V2O5: A 2D van der Waals Oxide with Strong In-Plane Electrical and Optical Anisotropy

V₂O₅ with a layered van der Waals (vdW) structure has been widely studied because of the material's potential in applications such as battery electrodes. In this work, microelectronic devices were fabricated to study the electrical and optical properties of mechanically exfoliated multilayered V₂O₅ flakes. Raman spectroscopy was used to determine the crystal structure axes of the nanoflakes and revealed that the intensities of the Raman modes depend strongly on the relative orientation between the crystal axes and the polarization directions of incident/scattered light. Angular dependence of four-probe resistance measured in the van der Pauw (vdP) configuration revealed an in-plane anisotropic resistance ratio of ∼100 between the a and b crystal axes, the largest in-plane transport anisotropy effect experimentally reported for two-dimensional (2D) materials to date. This very large resistance anisotropic ratio is explained by the nonuniform current flow in the vdP measurement and an intrinsic mobility anisotropy ratio of 10 between the a and b crystal axes. Room-temperature electron Hall mobility up to 7 cm²/(V s) along the high-mobility direction was obtained. This work demonstrates V₂O₅ as a layered 2D vdW oxide material with strongly anisotropic optical and electronic properties for novel applications.

CuO/V2O5 hybrid nanowires for highly sensitive and selective H2S gas sensor

Vanadium pentoxide (V₂O₅) nanowires decorated with CuO nanoparticles on their surface have been prepared by a facile chemical route.