V2O5 Composites Research Articles

Facile construction of efficient WO3/V2O5 coupled g-C3N4 ternary composite photocatalyst for environmental emergent aqueous pollutant degradation: Stability, degradation reaction pathway and effect of pH evaluation.

Currently, one of the primary challenges that human society must overcome is the task of decreasing the amount of energy used and the adverse effects that it has on the environment. The daily increase in liquid waste (comprising organic pollutants) is a direct result of the creation and expansion of new companies, causing significant environmental disruption. Water contamination is attributed to several industries such as textile, chemical, poultry, dairy, and pharmaceutical. In this study, we present the successful degradation of methylene blue dye using g-C3N4 (GCN) mixed with WO3 and V2O5 composites (GCN/WO3/V2O5 ternary composite) as a photocatalyst, prepared by a simple mechanochemistry method. The GCN/WO3/V2O5 ternary composite revealed a notable enhancement in photocatalytic performance, achieving around 97% degradation of aqueous methylene blue (MB). This performance surpasses that of the individual photocatalysts, namely pure GCN, GCN/WO3, and GCN/V2O5 composites. Furthermore, the GCN/WO3/V2O5 ternary composite exhibited exceptional stability even after undergoing five consecutive cycles. The exceptional photocatalytic activity of the GCN/WO3/V2O5 ternary composite can be ascribed to the synergistic effect of metal-free GCN and metal oxides, resulting in the alteration of the band gap and suppression of charge recombination in the ternary photocatalyst. This study offers a better platform for understanding the characteristics of materials and their photocatalytic performance under visible light conditions.

An exploratory investigation of the high pressure β-V2O5 polymorph as 3 V cathode material for potassium-ion battery

Electrochemical potassium-ion insertion in high pressure /high temperature (HP/HT) β-V2O5 polymorph is examined for the first time. Monoclinic HP/HT β-V2O5 delivers a high reversible capacity of 120 mAh g−1 at C/20 rate corresponding to the K0.8V2O5 composition, at an average discharge potential of 3.2 V vs. K+/K. A good cycling performance is achieved over at least 175 cycles at C/5 rate at room temperature, confirming HP/HT β-V2O5 is an efficient host material for K+ insertion-extraction reaction. First insight into the reversibility of the structural changes upon potassiation is given.

Alternating Current Response Study on PANI/V2O5 Composite at Room Temperature

In the present study, an Alternating Current (AC) response of Vanadium pentoxide (V2O5) doped Polyaniline (PANI) composite was studied. Pure PANI was synthesised by the In-situ polymerisation method. The PANI/Vanadium Pentoxide (PVO) composite was prepared by physical mixing of chemically synthesised PANI with dopant in a vibration mill. The structure and morphology of the samples were characterised by XRD and SEM studies. The Alternating Current response parameters of PANI, V2O5 and PVO composites were studied in the frequency scale of 40Hz to 110MHz at room temperature. The change in the AC conductivity of the composite as compared to PANI and V2O5 was observed and discussed based on the electron-hole exchange mechanism.

Hydrothermal transforming phase structure and chemical composition of V2O5 for elevating electrochemical property of zinc ion batteries

V2O5 was hydrothermally modified in NaOH or KOH solutions at 180 °C for 24 h. The NaOH-modified powders had a nanorod-like structure with a crystal structure matching Na2V6O16·nH2O. The TG/DTA results of Na2V6O16·nH2O powders show a mass reduction of 4.24 % at 300 °C, corresponding to n of 1.496. KOH-modified powders have large rods and irregular structures with a crystal structure matching KV3O8. Its TG/DTA spectrum shows a very small percentage change, just 0.37 % at 600 °C. Cyclic voltammetry (CV) curves of a Na2V6O16·nH2O cathode in a 2 M ZnSO4 electrolyte exhibit higher oxidation and reduction current densities than those of pure V2O5 and KV3O8 electrodes.The best capacity of a Na2V6O16·nH2O electrode is 296.10 mAh g-1 at a current density of 50 mA g−1, which is higher than those of pure V2O5 (102.90 mAh g-1) and KV3O8 (91.07 mAh g-1) electrodes. EDS and XPS results reveal that the charge and discharge states involve de-insertion and insertion of Zn2+ ions out of/into the electrodes. Computational analysis of Zn intercalation into V2O5, Na2V6O16·nH2O, and KV3O8 structures displays increasing electron density on neighboring V atoms, which explains the increasing V4+/V5+ ratio in the discharged state as evidenced by XPS spectra.

Photocatalytic activities of CTAB assisted ZrO2, V2O5, and ZrO2-V2O5 composite by precipitation process and their studies on structural, morphological and optical properties

Nanocrystalline core/shell structures of cetytrimethylammonium bromide (CTAB)-assisted ZrO2, V2O5, and ZrO2-V2O5 composite was successfully prepared by co-precipitation method calcined at 500 °C. CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite were characterized by different techniques such as, X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Brunauer-Emmett-Teller (BET), Ultra-Violet (UV) and Photoluminescence (PL). The formation of ZrO2, V2O5, and ZrO2-V2O5 composite material has been confirmed by XRD studies. Surface morphology with grain size of CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite was determined by SEM and TEM studies. EDX analysis confirms the presence of compositional elements of ZrO2-V2O5 composites in the lattice such as zirconium, vanadium and oxygen. Optical studies reveal a strong absorption and emission peaks were presented in the UV and visible regions and it useful for optoelectronic device applications. In comparison, ZrO2, V2O5, and ZrO2-V2O5 composite exhibited the higher band gap energies with a significant blue-shift and enhanced UV light absorption compared to bulk counterparts. As-prepared photocatalysts, CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite showed strong photocatalytic activity towards the degradation of Rhodamine B (RhB) dye under UV light irradiation, which can facilitate the efficient separation and migration of photo generated electron-hole pairs. Among result, the ZrO2-V2O5 composite exhibited the synergistic enhanced photocatalytic performance and also the possible photocatalytic mechanism was discussed in detail.

Preparation of polyaniline intercalated V2O5 composites and study of their self-charging mechanism

Vanadium oxides are an important aqueous zinc ion battery cathode material with the advantage of abundant reserves and high specific capacity. However, the strong interaction between the zinc ions and the main lattice of the material results in poor cycling stability and multiplicative performance of the cell. In this paper, we propose a molecular pre-embedding modification strategy for in situ intercalation of polyaniline. Flower cluster-like organic-inorganic (PANI-V2O5, PVO) hybrid materials with adjustable layer spacing were synthesized by simultaneous oxidative polymerization using vanadate and aniline as precursors without the introduction of inactive cations. PVO-60 exhibits a large specific capacity (391.1 mAh·g−1 at a current density of 0.2 A·g−1). The results of density flooding calculations demonstrate that the polyaniline layer blocks the electrostatic interaction between Zn2+ and the V2O5 backbone, thus promoting Zn2+ kinetics. Drawing on the air battery structure, a battery device that allows for air self-charging was designed using PVO-60 as the positive electrode. This work not only provides ideas for the design of vanadium oxides, but also offers the prospect of broadening the application of zinc ion batteries.

Physicochemical changes of hydroxyapatite, V2O5, and graphene oxide composites for medical usages

Physicochemical changes of hydroxyapatite, V2O5, and graphene oxide composites for medical usages

CATASTROPHIC OXIDATION OF AISI M4 ALLOY

In the annealing of some pure metals and various alloys, the phenomenon of accelerated oxidation is known, which is due to the fact that the resulting surface oxides fail to inhibit or completely stop the oxidation process. Vanadium ferrous alloys are rapidly oxidized during high-temperature annealing in oxygen atmospheres. The rate of oxidation is so great that it is considered a catastrophic oxidation. In this work, the AISI M4 alloy was investigated. The mechanism and model of the oxidation of alloy AISI M4 were developed on the basis of an analysis of the oxidation in a temperature range of 700–1000 °C. The holding time was 6 h. The alloy was analysed with an optical microscope and scanning electron microscopy equipped with EDS, WDS and EPMA detectors. It was found that below 850 °C, molten oxide is formed, which is predominantly of V2O5 composition. Above 850 °C, the oxide layer is multi-layered. The oxide layer consists of complex oxides, which formed with other elements. The X-ray analysis confirmed the presence of the following oxides in the oxide layer: Fe2O3, Cr2O3, FeVO4, V2O3 and Fe2WO6; and the second oxide may additionally be: V2O5, Cr2O5 and FeWO4.

Photocatalytic activity enhancement by composition control of mechano-thermally synthesized BiVO4-Cu2O nanocomposite

In this paper, BiVO4-Cu2O nanocomposites have been synthesized by a mechano-thermal method with a controlled composition of Bi2O3, V2O5 and Cu2O contents. The effects of milling time, heat treatment temperature and composition on the structure and microstructure of the prepared samples were studied. The optical properties and photocatalytic performance of the samples under visible light irradiation were studied by Diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and dye degradation. The BiVO4 and Cu2O contents in the nanocomposite were changed and the effects on the structural stability and photocatalytic performance were studied. X-ray diffraction (XRD) patterns showed that both BiVO4 and Cu2O contents were effective on the synthesis and stability of the monoclinic phase of BiVO4. Field emission scanning electron microscopy (FESEM) micrographs indicated semi-spherical nanocomposite particles with an average particle size of 100 nm. The heterostructure at the interface between Cu2O and BiVO4 was shown by Transmission electron microscopy (TEM) and proved by X-ray photoelectron spectroscopy (XPS) spectra. DRS results indicated the minimum band gap energy of 2.12 eV for BiVO4-10 wt% of Cu2O with a 10 wt% excessive V2O5 content. The PL result has shown the lowest rate of the recombination of electron-holes for this sample. Also, the maximum degradation of 97% has been obtained for methylene blue (MB) by this sample after 240 min of being irradiated in visible light region. The photocatalytic mechanism was determined using scavengers. The kinetics of MB and methyl orange (MO) degradations was compared to study the effect of pH on the photocatalytic performance.

The Current Developments and Perspectives of V2O5 as Cathode for Rechargeable Aqueous Zinc‐Ion Batteries

In recent years, zinc‐ion batteries (ZIBs) with near neutral (pH ≈ 4–6) Zn2+‐containing aqueous electrolyte have received extensive research due to their advantages of high safety, low production cost, suitable anode zinc, and environmental friendliness, etc. At present, one of the key challenges of aqueous ZIBs is the development of cathode materials with stable structure, rapid kinetics, and high capacity, etc. Compared with other cathode materials, V2O5 has an important potential application because of its high theoretical specific capacity (589 mA h g−1) based on two electron transfers, relatively low production cost, and suitable layered structure that facilitates zinc ion insertion/extraction. Herein, the following sections are proposed: 1) An understanding of the structure and energy storage mechanism of V2O5; 2) The recent development on the aqueous Zn/V2O5 battery from properties of V2O5 cathode and composition optimization of battery structure; 3) The application of V2O5 cathode in flexible ZIBs; and 4) The outlook and development trends in the future.

BiVO4/Cu0.4V2O5 composites as a novel Z-scheme photocatalyst for visible-light-driven CO2 conversion

A novel Z-scheme BiVO4/Cu0.4V2O5 heterojunction photocatalyst have been successfully constructed by growing Cu0.4V2O5 nanosheets on the surface of BiVO4 microplates using a simple co-precipitation method. The photocatalytic performance of BiVO4/Cu0.4V2O5 composites for CO2 reduction was evaluated under the visible-light irradiation. It was revealed that the photocatalytic performance of BiVO4/Cu0.4V2O5 composites varied with the Cu0.4V2O5 content and the composites with a mass ratio of 17.8 % Cu0.4V2O5 was found to be optimal for photocatalytic CO2 reduction. Especially, the optimized BiVO4/Cu0.4V2O5 exhibited a high CO evolution rate of 9.49 μmol g−1 h−1, which is about 4.4 times greater than that of the pristine Cu0.4V2O5. The significantly boosted photocatalytic activity of BiVO4/Cu0.4V2O5 composites is mainly ascribed to the superior charge-transport property derived from the novel Z-scheme structure.

Structural, optical, dielectric and transport properties of ball mill synthesized ZnO–V2O5 nano-composites

In the present study composites of ZnO and V2O5 (3, 6 and 9 mol%) were synthesized by solid state reaction method and the influence of V2O5 on the structural, microstructural, optical, dielectric and transport properties of final product have been investigated. The characterization of samples has been carried out by employing various experimental techniques such as XRD, FESEM, RAMAN, UV–Visible spectroscopy and photoluminescence. Information regarding the phase and structural parameters has been extracted using Rietveld refinements and microstructural using Williamson–Hall (W–H) analysis. Samples were also investigated for dc and ac electrical behavior. The present study revealed that the presence of V2O5 in ZnO–V2O5 composite plays a significant role in altering its structural, optical, dielectric and transport properties. An effort has also been made to correlate the structure with optical, dielectric and conduction properties of synthesized composites.

Synthesis, characterisation and catalytic activity of V2O5 nanoparticles using Foeniculum vulgare stem extract

A green synthesis route of metal oxide has been developed to synthesize the V2O5 nanoparticles. V2O5 was synthesized using Foeniculum vulgare stems extract (FSE) and ammonium monovanadate as precursors. The role of secondary metabolite compounds affect the particle size of V2O5. The crystalline phase and crystallite size of V2O5 were investigated by X-Ray Diffraction (XRD) with the orthorhombic crystalline phase and the average crystallite size around 78.6 nm. The presence of functional groups was evaluated by Fourier Transform Infrared (FT-IR). The morphology, particle size, and chemical composition of V2O5 were analyzed by Scanning Electron Microscopy (SEM), Tunneling Electron Microscopy (TEM) and Energy Dispersive X-Ray (EDX). V2O5 nanoparticles show a good catalytic activity for the reduction of methylene blue (MB).

Synergistic effect of band edge potentials on BiFeO3/V2O5 composite: Enhanced photo catalytic activity

The BiFeO3/V2O5 has been successfully synthesized by simple annealing of BiFeO3 nanoplates and V2O5 nanoflower. The phase, structural, optical properties and chemical state of the BiFeO3, V2O5 and different composition of BiFeO3/V2O5 samples were comparatively characterized by various spectroscopic and microscopic techniques. The prepared catalyst exhibits unique photo catalytic and post-oxidation/reduction ability for removal of various (MB, Phenol, CV, RhB) water organic pollutants. Compared to pure BiFeO3 and V2O5, the different Wt % of BiFeO3/V2O5 composition exhibited higher photo catalytic activity. The fortunate BiFeO3/V2O5 interface hybrid photo catalyst makes a significant impact in the enhancement of photo catalytic reaction. This remarkable efficiency could be ascribed to the synergistic effect between the V2O5 petals and BiFeO3 plates. The exceptional morphology, increased surface area, uniformity, less-agglomerated spreading could increase the ability of visible light response, which lead the improved electron transport ability and the higher charge separation. The enhanced rate of photo generated charge carriers separations were evinced by the EIS and PL spectrum measurements. The allowed radical trapping experiment divulge that the hole (h+), and super oxide radical (O2-) are the minimized effect in degradation, on the other hand hydroxyl radical (OH) is plays the foremost role and act as the active radicals in the catalytic organism. In relations of above investigation, a probable photo degradation mechanism of the as-synthesized photo catalyst is carefully explicated. This effort delivers an effective approach to design and fabricate the efficient photo catalyst through integrating of materials, which has a potential for industrial waste water purification.

Relation of photoluminescence and sunlight photocatalytic activities of pure V2O5 nanohollows and V2O5/RGO nanocomposites

Vanadium pentoxide (V2O5) nanospheres and nanohollows were fabricated by wet chemical reaction and hydrothermal methods. X-ray diffraction (XRD) and Raman spectroscopy reveal that the V2O5 nanostructures have an α-V2O5 phase with orthorhombic structure. Reduced graphene oxide (RGO) was mixed with pure V2O5 nanostructures to form V2O5/RGO nanocomposites. The composition of V2O5, RGO, and V4+ oxidation states was investigated by X-ray photoelectron spectroscopy (XPS). The presence of V4+ oxidation states due to oxygen vacancies in the V2O5 nanostructures leads to a wide range of absorption and direct photocatalytic activity under sunlight irradiation. The peak photoluminescence (PL) intensity is around 670 nm in the V2O5/RGO nanocomposites, which is much lower than that of pure V2O5. This seems to be evidence of facile electron transfer from V2O5 to RGO due to the strong adhesion of RGO with pores on the V2O5 surface. This leads to the enhancement of the sunlight photocatalytic activity of the V2O5/RGO nanocomposites. The relation between the separation, diffusion, recombination, and degradation of the electron-hole pairs in the V2O5 nanostructures and V2O5/RGO nanocomposite is discussed.

Mass ablated controlled laser induced V2O5 plasma parameters for controllable VO2 films growth

The effect of the laser fluence on V2O5 plasma dynamics, composition, and ionization state was studied. By combining three plasma diagnostic techniques, fast imaging, optical emission spectroscopy, and Langmuir probe, two ablation regimes have been identified. These ablation regimes depend on the evolution of the amount of the ablated mass that was measured by the method of mass loss. The transition between the two regimes at 1.3 J cm−2. For fluences lower than this threshold value, the expansion velocity of the plasma elements, the plasma dimensions, and the ionic current increase rapidly, unlike the fluences higher than the threshold fluence. Reverse behavior was observed for the ablated mass. This effect of the ablated mass would have a significant impact on the control of the properties of vanadium dioxide layers deposited by pulsed laser deposition in a reactive atmosphere of oxygen.

Preparation and comparison of hybridized WO3–V2O5 nanocomposites electrochemical supercapacitor performance in KOH and H2SO4 electrolyte

The rod shape WO3–V2O5 hybrid nanocomposites were prepared by microwave assisted wet chemical route. The electrochemical investigations of as-prepared composites were carried in two electrolytes such as KOH and H2SO4 for comparison. Their maximum capacitance was calculated as 44 F/g for WO3 and 173 F/g for WO3–V2O5 composites in KOH electrolyte and its efficiency is 100% up to 5000 cycles and its capacitance retention is ∼126% in KOH electrolyte. In H2SO4 electrolyte, the specific capacitance of WO3 was recorded as 246 F/g and WO3–V2O5 showed poor performance such as less than 12 F/g.

Synthesis of vanadium-pentoxide-supported graphitic carbon nitride heterostructure and studied their hydrogen evolution activity under solar light

Noble-metal-free co-catalyst supported with a highly active and stable photocatalyst is of considerable importance to realize low cost and scaled up photocatalytic hydrogen evolution. An inorganic–organic two-dimensional (2D)/one-dimensional (1D) graphitic carbon nitride (g-C3N4) nanosheet anchored with a vanadium pentoxide (V2O5) nanoparticle heterojunction photocatalyst (GCN/V2O5-3) with excellent solar-light-driven photocatalytic performance was prepared using a facile thermal decomposition method and used for photocatalytic hydrogen (H2) evolution from concentrated lactic acid aqueous solution. The optimized GCN/V2O5-3 catalyst attained a high initial H2 evolution rate of 2891.53 µmol g−1, which is 2.44 times greater than that of pristine g-C3N4 under simulated solar light irradiation. In addition, the GCN/V2O5-3 catalyst is relatively stable for 5 h H2 evolution reactions, indicating the robustness of the V2O5 co-catalyst. The improved photocatalytic activity of the g-C3N4/V2O5 composites can be ascribed to their large specific surface area. Photoelectrochemical analysis results clearly show that V2O5 co-catalyst captures photoinduced holes from the valance band of the excited g-C3N4 by a Z-scheme mechanism and thus improving the charge separation performance and endorse the H+ reduction to H2. Lastly, the mechanism of photocatalytic H2 evolution of the g-C3N4/V2O5 composite is discussed. Importantly, because of its high stability, easy processing, and low cost, the V2O5 co-catalyst has abundant potential in designing high-performance-semiconductor/organic photocatalysts for large-scale H2 production utilizing renewable energy sources.

Synthesis of Au decorated V2O5 microflowers with enhanced sensing properties towards amines

This study developed an innovative two-step method to synthesize hybrid gold decorated nanosheet-assembled V2O5 microflowers (Au/V2O5), through in-situ reduction of Au nanoparticles on nanosheet-assembled V2O3 microflowers at room temperature in aqueous solution and further thermal oxidization as V2O5. Various characterization techniques were employed, such as SEM, TEM, XRD, EDX, XPS, and BET, to reveal that Au nanoparticles (diameter of ~10 nm) evenly attached on the surface of nanosheet-assembled V2O5 nanoparticles (diameters of ~1–2 μm). This method shows several advantages in generating such nanocomposites: low cost, highly efficient, room-temperature and easy operation, as well as no need for extra reducing agents and surfactants. The gas sensing properties of the Au/V2O5 composites were investigated toward toxic 1-butylamine, an important marker compound in food and medical industries, showing that the Au modification can effectively enhance the sensing performance: high response (100 ppm of 1-butylamine), high selectivity, and low working temperature (~240 °C), compared to bare V2O5 microflowers. The effect of the molar ratio of Au to V2O5 on nanostructure and sensing property was also investigated. The findings may bring a new insight into the fabrication of noble metal(s) modified V2O5 composites with high sensing performance.

Nitrogen-doped carbon-coated V2O5 nanocomposite as cathode materials for lithium-ion battery

V2O5 has a high theoretical capacity of 440 mAh g−1 as cathode materials for lithium ion batteries. However, the poor conductivity may affect the lithiation/delithiation behavior greatly. This study effectively solves the poor conductivity and lithium ion migration rate of V2O5. Nitrogen-doped carbon-coated V2O5 composites (NCNPs-V2O5) are synthesized via an organic solvent assisted in situ hydrothermal growth method. Owing to the NCNPs and their novel 3D flower structure, the as-prepared NCNPs-V2O5 exhibited remarkable electrochemical performance as cathode material of lithium ion battery.