The Synthesis of Sponge-like V2O5/CNT Hybrid Nanostructures Using Vertically Aligned CNTs as Templates

The fabrication of sponge-like vanadium pentoxide (V2O5) nanostructures using vertically aligned carbon nanotubes (VACNTs) as a template is presented. The VACNTs were grown on silicon substrates by chemical vapor deposition using the Fe/Al bilayer catalyst approach. The V2O5 nanostructures were obtained from the thermal oxidation of metallic vanadium deposited on the VACNTs. Different oxidation temperatures and vanadium thicknesses were used to study the influence of these parameters on the stability of the carbon template and the formation of the V2O5 nanostructures. The morphology of the samples was analyzed by scanning electron microscopy, and the structural characterization was performed by Raman, energy-dispersive X-ray, and X-ray photoelectron spectroscopies. Due to the catalytic properties of V2O5 in the decomposition of carbonaceous materials, it was possible to obtain supported sponge-like structures based on V2O5/CNT composites, in which the CNTs exhibit an increase in their graphitization. The VACNTs can be removed or preserved by modulating the thermal oxidation process and the vanadium thickness.

Design Strategy of High Stability Vertically Aligned RGO@V2O5 Heterostructure Cathodes for Flexible Quasi-Solid-State Aqueous Zinc-Ion Batteries

Among various cathodes for aqueous zinc-ion batteries (AZIBs), vanadium-based oxides have garnered significant attention in research circles owing to their exceptionally high theoretical specific capacity. However, the outstanding zinc storage capacity of vanadium pentoxide is constrained by its irreversible dissolution in an aqueous solution. Here, we propose a laser reduction of graphene oxide and construct a heterostructure of V2O5 coated with vertically aligned reduced graphene oxide (VrGO). The VrGO nanosheets effectively suppress the dissolution of V2O5 and provide channels for the efficient transport of zinc ions and electrons, so the electrochemical reaction kinetics of the electrode are improved. The AZIB based on the VrGO@V2O5 heterostructure cathode has a high specific capacity of 254.9 mAh g-1 at 0.2 A g-1 and excellent cycle stability with a capacity retention rate of 90.1% after 5000 cycles of charge and discharge. When assembled into a flexible quasi-solid-state AZIB, the capacity of the device is reduced by only 2% after 1000 bending cycles, showing good potential for wearable applications. This work provides a reliable strategy for designing flexible AZIB with high electrochemical performance and structural stability.

Metal-Ion Intercalation Mechanisms in Vanadium Pentoxide and Its New Perspectives

The investigation into intercalation mechanisms in vanadium pentoxide has garnered significant attention within the realm of research, primarily propelled by its remarkable theoretical capacity for energy storage. This comprehensive review delves into the latest advancements that have enriched our understanding of these intricate mechanisms. Notwithstanding its exceptional storage capacity, the compound grapples with challenges arising from inherent structural instability. Researchers are actively exploring avenues for improving electrodes, with a focus on innovative structures and the meticulous fine-tuning of particle properties. Within the scope of this review, we engage in a detailed discussion on the mechanistic intricacies involved in ion intercalation within the framework of vanadium pentoxide. Additionally, we explore recent breakthroughs in understanding its intercalation properties, aiming to refine the material's structure and morphology. These refinements are anticipated to pave the way for significantly enhanced performance in various energy storage applications.

The Recovery of Vanadium Pentoxide (V2O5) from Spent Catalyst Utilized in a Sulfuric Acid Production Plant in Jordan

Vanadium is a significant metal, and its derivatives are widely employed in industry. One of the essential vanadium compounds is vanadium pentoxide (V2O5), which is mostly recovered from titanomagnetite, uranium-vanadium deposits, phosphate rocks, and spent catalysts. A smart method for the characterization and recovery of vanadium pentoxide (V2O5) was investigated and implemented as a small-scale benchtop model. Several nondestructive analytical techniques, such as particle size analysis, X-ray fluorescence (XRF), inductively coupled plasma (ICP), and X-ray diffraction (XRD) were used to determine the physical and chemical properties, such as the particle size and composition, of the samples before and after the recovery process of vanadium pentoxide (V2O5). After sample preparation, several acid and alkali leaching techniques were investigated. A noncorrosive, environmentally friendly extraction method based on the use of less harmful acids was applied in batch and column experiments for the extraction of V2O5 as vanadium ions from a spent vanadium catalyst. In batching experiments, different acids and bases were examined as leaching solution agents; oxalic acid showed the best percent recovery for vanadium ions compared with the other acids used. The effects of the contact time, acid concentration, solid-to-liquid ratio, stirring rate, and temperature were studied to optimize the leaching conditions. Oxalic acid with a 6% (w/w) to a 1/10 solid-to-liquid ratio at 300 rpm and 50 °C was the optimal condition for extraction (67.43% recovery). On the other hand, the column experiment with a 150 cm long and 5 cm i.d. and 144 h contact time using the same leaching reagent, 6% oxalic acid, showed a 94.42% recovery. The results of the present work indicate the possibility of the recovery of vanadium pentoxide from the spent vanadium catalyst used in the sulfuric acid industry in Jordan.

Vanadium Pentoxide Exposure Causes Strain-Dependent Changes in Mitochondrial DNA Heteroplasmy, Copy Number, and Lesions, but Not Nuclear DNA Lesions

Interstitial lung diseases (ILDs) are lethal lung diseases characterized by pulmonary inflammation and progressive lung interstitial scarring. We previously developed a mouse model of ILD using vanadium pentoxide (V2O5) and identified several gene candidates on chromosome 4 associated with pulmonary fibrosis. While these data indicated a significant genetic contribution to ILD susceptibility, they did not include any potential associations and interactions with the mitochondrial genome that might influence disease risk. To conduct this pilot work, we selected the two divergent strains we previously categorized as V2O5-resistant C57BL6J (B6) and -responsive DBA/2J (D2) and compared their mitochondrial genome characteristics, including DNA variants, heteroplasmy, lesions, and copy numbers at 14- and 112-days post-exposure. While we did not find changes in the mitochondrial genome at 14 days post-exposure, at 112 days, we found that the responsive D2 strain exhibited significantly fewer mtDNA copies and more lesions than control animals. Alongside these findings, mtDNA heteroplasmy frequency decreased. These data suggest that mice previously shown to exhibit increased susceptibility to pulmonary fibrosis and inflammation sustain damage to the mitochondrial genome that is evident at 112 days post-V2O5 exposure.

Fast One-Step Fabrication of Highly Regular Microscrolls with Controllable Surface Morphology

Although rolling origami technology has provided convenient access to three-dimensional (3D) microstructure systems, the high yield and scalable construction of complex rolling structures with well-defined geometry without impeding functionality has remained challenging. The straightforward, one-step fabrication that uses external mechanical stress to scroll micrometer thick, flexible planar films with centimeter lateral dimensions into tubular or spiral geometry within a few seconds is demonstrated. The method allows controlling the scrolls' diameter, number of windings and nanostructured surface morphology, and is applicable to a wide range of functional materials. The obtained 3D structures are highly promising for various applications including sensors, actuators, microrobotics, as well as energy storage and electronic devices.

A Heterogeneous Single Atom Cobalt Catalyst for Highly Efficient Acceptorless Dehydrogenative Coupling Reactions

A fundamental understanding of metal active sites in single-atom catalysts (SACs) is important and challenging in the development of high-performance catalyst systems. Here, a highly efficient and straightforward molten-salt-assisted approach is reported to create atomically dispersed cobalt atoms supported over vanadium pentoxide layered material, with each cobalt atom coordinated with four neighboring oxygen atoms. The liquid environment and the strong polarizing force of the molten salt at high temperatures potentially favor the weakening of VO bonding and the formation of CoO bonding on the vanadium oxide surface. This cobalt SAC achieves extraordinary catalytic efficiency in acceptorless dehydrogenative coupling of alcohols with amines to give imines, with more than 99% selectivity under almost 100% conversion within 3 h, along with a high turnover frequency (TOF) of 5882 h^-1 , exceeding those of previously reported benchmarking catalysts. Moreover, it delivers excellent recyclability, reaction scalability, and substrate tolerance. Density functional theory (DFT) calculations further confirm that the optimized coordination environment and strong electronic metal-support interaction contribute significantly to the activation of reactants. The findings provide a feasible route to construct SACs at the atomic level for use in organic transformations.

Room Temperature Ammonia Gas Sensor Based on p-Type-like V2O5 Nanosheets towards Food Spoilage Monitoring

Gas sensors play an important role in many areas of human life, including the monitoring of production processes, occupational safety, food quality assessment, and air pollution monitoring. Therefore, the need for gas sensors to monitor hazardous gases, such as ammonia, at low operating temperatures has become increasingly important in many fields. Sensitivity, selectivity, low cost, and ease of production are crucial characteristics for creating a capillary network of sensors for the protection of the environment and human health. However, developing gas sensors that are not only efficient but also small and inexpensive and therefore integrable into everyday life is a difficult challenge. In this paper, we report on a resistive sensor for ammonia detection based on thin V₂O₅ nanosheets operating at room temperature. The small thickness and porosity of the V₂O₅ nanosheets give the sensors good performance for sensing ammonia at room temperature (RT), with a relative change of resistance of 9.4% to 5 ppm ammonia (NH₃) and an estimated detection limit of 0.4 ppm. The sensor is selective with respect to the seven interferents tested; it is repeatable and stable over the long term (four months). Although V₂O₅ is generally an n-type semiconductor, in this case the nanosheets show a p-type semiconductor behavior, and thus a possible sensing mechanism is proposed. The device's performance, along with its size, low cost, and low power consumption, makes it a good candidate for monitoring freshness and spoilage along the food supply chain.

VOx Phase Mixture of Reduced Single Crystalline V2O5: VO2 Resistive Switching

The strongly correlated electron material, vanadium dioxide (VO2), has seen considerable attention and research application in metal-oxide electronics due to its metal-to-insulator transition close to room temperature. Vacuum annealing a V2O5(010) single crystal results in Wadsley phases (VnO2n+1, n > 1) and VO2. The resistance changes by a factor of 20 at 342 K, corresponding to the metal-to-insulator phase transition of VO2. Macroscopic voltage-current measurements with a probe separation on the millimetre scale result in Joule heating-induced resistive switching at extremely low voltages of under a volt. This can reduce the hysteresis and facilitate low temperature operation of VO2 devices, of potential benefit for switching speed and device stability. This is correlated to the low resistance of the system at temperatures below the transition. High-resolution transmission electron microscopy measurements reveal a complex structural relationship between V2O5, VO2 and V6O13 crystallites. Percolation paths incorporating both VO2 and metallic V6O13 are revealed, which can reduce the resistance below the transition and result in exceptionally low voltage resistive switching.

Skin-Inspired Thermoreceptors-Based Electronic Skin for Biomimicking Thermal Pain Reflexes

Electronic systems possessing skin-like morphology and functionalities (electronic skins [e-skins]) have attracted considerable attention in recent years to provide sensory or haptic feedback in growing areas such as robotics, prosthetics, and interactive systems. However, the main focus thus far has been on the distributed pressure or force sensors. Herein a thermoreceptive e-skin with biological systems like functionality is presented. The soft, distributed, and highly sensitive miniaturized (≈700 µm² ) artificial thermoreceptors (ATRs) in the e-skin are developed using an innovative fabrication route that involves dielectrophoretic assembly of oriented vanadium pentoxide nanowires at defined locations and high-resolution electrohydrodynamic printing. Inspired from the skin morphology, the ATRs are embedded in a thermally insulating soft nanosilica/epoxy polymeric layer and yet they exhibit excellent thermal sensitivity (-1.1 ± 0.3% °C^-1 ), fast response (≈1s), exceptional stability (negligible hysteresis for >5 h operation), and mechanical durability (up to 10 000 bending and twisting loading cycles). Finally, the developed e-skin is integrated on the fingertip of a robotic hand and a biological system like reflex is demonstrated in response to temperature stimuli via localized learning at the hardware level.

Design of Vertically Aligned Two-Dimensional Heterostructures of Rigid Ti3C2TX MXene and Pliable Vanadium Pentoxide for Efficient Lithium Ion Storage

Designing a thick electrode with appropriate mass loading is a prerequisite toward practical applications for lithium ion batteries (LIBs) yet suffers severe limitations of slow electron/ion transport, unavoidable volume expansion, and the involvement of inactive additives, which lead to compromised output capacity, poor rate perforamnce, and cycling instability. Herein, self-supported thick electrode composed of vertically aligned two-dimensional (2D) heterostructures (V-MXene/V₂O₅) of rigid Ti₃C₂T_X MXene and pliable vanadium pentoxide are assembled via an ice crystallization-induced strategy. The vertical channels prompt fast electron/ion transport within the entire electrode; in the meantime, the 3D MXene scaffold provides mechanical robustness during lithiation/delithiation. The optimized electrodes with 1 and 5 mg cm^-2 of V-MXene/V₂O₅ respectively deliver 472 and 300 mAh g^-1 at a current density of 0.2 A g^-1, rate performance with 380 and 222 mAh g^-1 retained at 5 A g^-1, and reliability over 800 charge/discharge cycles.

Analysis of Hydrometallurgical Methods for Obtaining Vanadium Concentrates from the Waste by Chemical Production of Vanadium Pentoxide

The paper describes hydrometallurgical methods to recycle wastes of vanadium pentoxide chemical fabrication. Sludges containing a significant amount of V₂O₅ can be considered as an additional source of raw materials for vanadium production. We studied the one-stage leaching method using various iron-based reductants for converting V⁵⁺ to V⁴⁺ in a solution allowing to precipitate V when its concentration in the solution is low. As a result of the reduction leaching with further precipitation, we obtained concentrates with V₂O₅ content of 22–26% and a high amount of harmful impurities. Multistage counterflow leaching can be used to fabricate solutions with vanadium pentoxide concentration suitable for vanadium precipitation by hydrolysis and adding ammonium salts. The solutions with V₂O₅ content of ≈15 g/L can be obtained from the initial sludge by three-stage counterflow vanadium leaching. A concentrate with a content of 78 wt% V₂O₅ can be precipitated from these solutions at pH = 2.4 by adding ammonium chloride. Additionally, concentrate with V₂O₅ content of ≈94 wt% was precipitated from the solution with a concentration of >20 g/L V₂O₅ obtained from the roasted sludge. The concentrates were purified for increasing the vanadium content to 5–7%. The consumption and technological parameters of the considered processes are presented in the paper.

Recent Development in Vanadium Pentoxide and Carbon Hybrid Active Materials for Energy Storage Devices

With the increasing energy demand for portable electronics, electric vehicles, and green energy storage solutions, the development of high-performance supercapacitors has been at the forefront of energy storage and conversion research. In the past decade, many scientific publications have been dedicated to designing hybrid electrode materials composed of vanadium pentoxide (V2O5) and carbon nanomaterials to bridge the gap in energy and power of traditional batteries and capacitors. V2O5 is a promising electrode material owing to its natural abundance, nontoxicity, and high capacitive potential. However, bulk V2O5 is limited by poor conductivity, low porosity, and dissolution during charge/discharge cycles. To overcome the limitations of V2O5, many researchers have incorporated common carbon nanostructures such as reduced graphene oxides, carbon nanotubes, carbon nanofibers, and other carbon moieties into V2O5. The carbon components facilitate electron mobility and act as porous templates for V2O5 nucleation with an enhanced surface area as well as interconnected surface morphology and structural stability. This review discusses the development of various V2O5/carbon hybrid materials, focusing on the effects of different synthesis methods, V2O5/carbon compositions, and physical treatment strategies on the structure and electrochemical performance of the composite material as promising supercapacitor electrodes.

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.

Progress on V2O5 Cathodes for Multivalent Aqueous Batteries

Research efforts have been focused on developing multivalent ion batteries because they hold great promise and could be a major advancement in energy storage, since two or three times more charge per ion can be transferred as compared with lithium. However, their application is limited because of the lack of suitable cathode materials to reversibly intercalate multivalent ions. From that perspective, vanadium pentoxide is a promising cathode material because of its low toxicity, ease of synthesis, and layered structure, which provides huge possibilities for the development of energy storage devices. In this mini review, the general strategies required for the improvement of reversibility, capacity value, and stability of the cathodes is presented. The role of nanostructural morphologies, structure, and composites on the performance of vanadium pentoxide in the last five years is addressed. Finally, perspectives on future directions of the cathodes are proposed.

Vanadium Pentoxide Nanofibers/Carbon Nanotubes Hybrid Film for High-Performance Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) with the characteristics of low production costs and good safety have been regarded as ideal candidates for large-scale energy storage applications. However, the nonconductive and non-redox active polymer used as the binder in the traditional preparation of electrodes hinders the exposure of active sites and limits the diffusion of ions, compromising the energy density of the electrode in ZIBs. Herein, we fabricated vanadium pentoxide nanofibers/carbon nanotubes (V₂O₅/CNTs) hybrid films as binder-free cathodes for ZIBs. High ionic conductivity and electronic conductivity were enabled in the V₂O₅/CNTs film due to the porous structure of the film and the introduction of carbon nanotubes with high electronic conductivity. As a result, the batteries based on the V₂O₅/CNTs film exhibited a higher capacity of 390 mAh g^-1 at 1 A g^-1, as compared to batteries based on V₂O₅ (263 mAh g^-1). Even at 5 A g^-1, the battery based on the V₂O₅/CNTs film maintained a capacity of 250 mAh g^-1 after 2000 cycles with a capacity retention of 94%. In addition, the V₂O₅/CNTs film electrode also showed a high energy/power density (e.g., 67 kW kg^-1/267 Wh kg^-1). The capacitance response and rapid diffusion coefficient of Zn²⁺ (~10^-8 cm^-2 s^-1) can explain the excellent rate capability of V₂O₅/CNTs. The vanadium pentoxide nanofibers/carbon nanotubes hybrid film as binder-free cathodes showed a high capability and a stable cyclability, demonstrating that it is highly promising for large-scale energy storage applications.

In-Silico Monte Carlo Simulation Trials for Investigation of V2O5 Reinforcement Effect on Ternary Zinc Borate Glasses: Nuclear Radiation Shielding Dynamics

In the current study, promising glass composites based on vanadium pentoxide (V₂O₅)-doped zinc borate (ZnB) were investigated in terms of their nuclear-radiation-shielding dynamics. The mass and linear attenuation coefficient, half-value layer, mean free path, tenth-value layer, effective atomic number, exposure-buildup factor, and energy-absorption-buildup factor were deeply simulated by using MCNPX code, Phy-X PSD code, and WinXcom to study the validation of ZBV1, ZBV2, ZBV3, and ZBV4 based on (100−x)(0.6ZnO-0.4B₂O₃)(x)(V₂O₅) (x = 1, 2, 3, 4 mol%) samples against ionizing radiation. The results showed that attenuation competencies of the studied glasses slightly changed while increasing the V₂O₅ content from 1 mol% to 4 mol%. The domination of ZnO concentration in the composition compared to B₂O₃ makes ZnO substitution with V₂O₅ more dominant, leading to a decrease in density. Since density has a significant role in the attenuation of gamma rays, a negative effect was observed. It can be concluded that the aforementioned substitution can negatively affect the shielding competencies of studied glasses.

Polyaniline Encapsulated Amorphous V2 O5 Nanowire-Modified Multi-Functional Separators for Lithium-Sulfur Batteries

Designing multi-functional separators is one of the effective strategies for achieving high-performance lithium-sulfur (Li-S) batteries. In this work, polyaniline (PANI) encapsulated amorphous vanadium pentoxide (V₂ O₅ ) nanowires (general formula V₂ O₅ ·nH₂ O and abbreviated as VOH) are synthesized by a facile in situ chemical oxidative polymerization method, and utilized as a basic building block for the preparation of functional interlayers on the commercial polypropylene (PP) separator, generating a VOH@PANI-PP separator with multi-functionalities. Compared to the crystalline V₂ O₅ , the amorphous V₂ O₅ shows enhanced properties of polysulfide adsorption, catalytic activity, as well as ionic conductivity. Therefore, within the VOH@PANI-PP separator, the amorphous V₂ O₅ nanowire component contributes to the strong adsorption of polysulfides, the high catalytic activity for polysulfides conversion, and the high ionic conductivity. The PANI component further strengthens the above effects, improves the electrical conductivity, and enhances the flexibility of the modified separator. Benefiting from the synergistic effects, the VOH@PANI-PP separator effectively suppresses polysulfide shuttling and improves the cycling stability of its composed Li-S batteries. This work provides a new research strategy for the development of efficient separators in rechargeable batteries by judiciously integrating the amorphous metal oxide with a conductive polymer.

Electrochemical Proton Intercalation in Vanadium Pentoxide Thin Films and its Electrochromic Behavior in the near-IR Region

This work examines the proton intercalation in vanadium pentoxide (V2 O5 ) thin films and its optical properties in the near-infrared (near-IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V2 O5 in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well-defined number of protons in the Hx V2 O5 system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near-IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy's dispersion model. The results show a clear correlation between proton concentration and n and k.

Towards High Performance Chemical Vapour Deposition V2O5 Cathodes for Batteries Employing Aqueous Media

The need for clean and efficient energy storage has become the center of attention due to the eminent global energy crisis and growing ecological concerns. A key component in this effort is the ultra-high performance battery, which will play a major role in the energy industry. To meet the demands in portable electronic devices, electric vehicles, and large-scale energy storage systems, it is necessary to prepare advanced batteries with high safety, fast charge ratios, and discharge capabilities at a low cost. Cathode materials play a significant role in determining the performance of batteries. Among the possible electrode materials is vanadium pentoxide, which will be discussed in this review, due to its low cost and high theoretical capacity. Additionally, aqueous electrolytes, which are environmentally safe, provide an alternative approach compared to organic media for safe, cost-effective, and scalable energy storage. In this review, we will reveal the industrial potential of competitive methods to grow cathodes with excellent stability and enhanced electrochemical performance in aqueous media and lay the foundation for the large-scale production of electrode materials.

Electrochromic Performance of V2O5 Thin Films Grown by Spray Pyrolysis

A new approach regarding the development of nanostructured V₂O₅ electrochromic thin films at low temperature (250 °C), using air-carrier spray deposition and ammonium metavanadate in water as precursor is presented. The obtained V₂O₅ films were characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy, while their electrochromic response was studied using UV-vis absorption spectroscopy and cyclic voltammetry. The study showed that this simple, cost effective, suitable for large area deposition method can lead to V₂O₅ films with large active surface for electrochromic applications.

Tuning the Kinetics of Zinc-Ion Insertion/Extraction in V2 O5 by In Situ Polyaniline Intercalation Enables Improved Aqueous Zinc-Ion Storage Performance

Rechargeable zinc-ion batteries (ZIBs) are emerging as a promising alternative for Li-ion batteries. However, the developed cathodes suffer from sluggish Zn²⁺ diffusion kinetics, leading to poor rate capability and inadequate cycle life. Herein, an in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn²⁺ (de)intercalation kinetics in V₂ O₅ . In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the VO layers, offering expediting channels for facile Zn²⁺ diffusion. Importantly, the electrostatic interactions between the Zn²⁺ and the host O^2- , which is another key factor in hindering the Zn²⁺ diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V₂ O₅ exhibits a stable and highly reversible electrochemical reaction during repetitive Zn²⁺ insertion and extraction, as demonstrated by in situ synchrotron X-ray diffraction and Raman studies. Further first-principles calculations clearly reveal a remarkably lowered binding energy between Zn²⁺ and host O^2- , which explains the favorable kinetics in PANI-intercalated V₂ O₅ . Benefitting from the above, the overall electrochemical performance of PANI-intercalated V₂ O₅ electrode is remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g^-1 at current density of 20 A g^-1 with capacity retention of 97.6% over 2000 cycles.

Modification of Graphene Oxide/V2O5·nH2O Nanocomposite Films via Direct Laser Irradiation

Herein, photothermal modification of nanocomposite films consisting of hydrated vanadium pentoxide (V₂O₅·nH₂O) nanoribbons wrapped with graphene oxide (GO) flakes was performed via 405 nm direct laser irradiation. The combination of X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering, transmission electron microscopy, and scanning electron microscopy allowed comprehensive characterization of physical and chemical changes of GO/V₂O₅·nH₂O nanocomposite films upon photothermal modification. The modified nanocomposite films exhibited porous surface morphology (17.27 m² g^-1) consisting of randomly distributed pillarlike protrusions. The photothermal modification process of GO/V₂O₅·nH₂O enhanced the electrical conductivity of nanocomposite from 1.6 to 6.8 S/m. It was also determined that the direct laser irradiation of GO/V₂O₅·nH₂O resulted in considerable decrease of C-O bounds as well as O-H functional groups with an increase of the laser power density.

Morphological Control of Nanostructured V2O5 by Deep Eutectic Solvents

Herein, we show a facile surfactant-free synthetic platform for the synthesis of nanostructured vanadium pentoxide (V₂O₅) using reline as a green and eco-friendly deep eutectic solvent. This new approach overcomes the dependence of the current synthetic methods on shape directing agents such as surfactants with potential detrimental effects on the final applications. Excellent morphological control is achieved by simply varying the water ratio in the reaction leading to the selective formation of V₂O₅ 3D microbeads, 2D nanosheets, and 1D randomly arranged nanofleece. Using electrospray ionization mass spectroscopy (ESI-MS), we demonstrate that alkyl amine based ionic species are formed during the reline/water solvothermal treatment and that these play a key role in the resulting material morphology with templating and exfoliating properties. This work enables fundamental understanding of the activity-morphology relationship of vanadium oxide materials in catalysis, sensing applications, energy conversion, and energy storage as we prove the effect of surfactant-free V₂O₅ structuring on battery performance as cathode materials. Nanostructured V₂O₅ cathodes showed a faster charge-discharge response than the counterpart bulk-V₂O₅ electrode with V₂O₅ 2D nanosheet presenting the highest improvement of the rate performance in galvanostatic charge-discharge tests.

Interface Engineering V2 O5 Nanofibers for High-Energy and Durable Supercapacitors

A local electric field is induced to engineer the interface of vanadium pentoxide nanofibers (V₂ O₅ -NF) to manipulate the charge transport behavior and obtain high-energy and durable supercapacitors. The interface of V₂ O₅ -NF is modified with oxygen vacancies (Vö) in a one-step polymerization process of polyaniline (PANI). In the charge storage process, the local electric field deriving from the lopsided charge distribution around Vö will provide Coulombic forces to promote the charge transport in the resultant Vö-V₂ O₅ /PANI nanocable electrode. Furthermore, an ≈7 nm porous PANI coating serves as the external percolated charge transport pathway. As the charge transfer kinetics are synergistically enhanced by the dual modifications, Vö-V₂ O₅ /PANI-based supercapacitors exhibit an excellent specific capacitance (523 F g^-1 ) as well as a long cycling lifespan (110% of capacitance remained after 20 000 cycles). This work paves an effective way to promote the charge transfer kinetics of electrode materials for next-generation energy storage systems.

Vanadium Organometallics as an Interfacial Stabilizer for Ca xV2O5/Vanadyl Acetylacetonate Hybrid Nanocomposite with Enhanced Energy Density and Power Rate for Full Lithium-Ion Batteries

Vanadium pentoxide (V₂O₅) offers high capacity and energy density as a cathode candidate for lithium-ion batteries (LIBs). Unfortunately, its practical utilization is intrinsically handicapped by the low conductivity, poor electrode kinetics, and lattice instability. In this study, the synergistical optimization protocol has been proposed in the conjunction of interstitial Ca incorporation and organic vanadate surface protection. It is revealed that regulating Ca occupation in the body phase at a relatively low concentration can effectively expand the layer distance of α-V₂O₅, which facilitates the intercalation access for Li-ion insertion. On the other hand, organometallics are first applied as the protective layer to stabilize the electrode interface during cycling. The optimized coating layer, vanadium oxy-acetylacetonate (VO(acac)₂), plays an important role to generate a more inorganic component (LiF) within the solid electrolyte interface, contributing to the protection of the Ca-incorporated V₂O₅ electrode. As a result, the optimized Ca_0.05V₂O₅/VO(acac)₂ hybrid electrode exhibits much improved capacity utilization, rate capability, and cycling stability, delivering capacity as high as 297 mAh g^-1 for full LIBs. The first-principle computations reveal the lattice change caused by the Ca incorporation, further confirming the lattice advantage of Ca_0.05V₂O₅/VO(acac)₂ with respect to Li-ion intercalation.

Aqueous Al-Ion Supercapacitor with V2O5 Mesoporous Carbon Electrodes

A high-performance, low-cost, aqueous Al-ion supercapacitor was fabricated based on nanostructured V₂O₅ impregnated mesoporous carbon microspheres (MCM/V₂O₅) electrodes and Al₂(SO₄)₃ electrolyte for efficient energy storage. MCM/V₂O₅ composites exhibit high dispersion of nanostructured V₂O₅ in a mesoporous carbon matrix, beneficial to fast reversible redox reactions with a short diffusion path. The corresponding capacitor illustrates the distinguishable redox behavior, most likely due to the Al³⁺ intercalation/deintercalation leading to the reduction/oxidation of V⁵⁺/V⁴⁺. It delivers a high-energy density of 18.0 Wh kg^-1 at 147 W kg^-1 and a long cycling lifespan with over 88% capacitance retention over 10 000 cycles. The competitive performance can be ascribed to the integration of the electric double layer capacitance provided from MCM with pseudocapacitance contributed by nanostructured V₂O₅. This work offers the possibilities of high-performance aqueous capacitors based on trivalent Al-ion as guest species, providing new directions for future development of supercapacitors.

Self-Doped Conjugated Polymeric Binders Improve the Capacity and Mechanical Properties of V₂O₅ Cathodes

Polymeric binders serve to stabilize the morphology of electrodes by providing adhesion and binding between the various components. Successful binders must serve multiple functions simultaneously, including providing strong adhesion, improving conductivity, and providing electrochemical stability. A tradeoff between mechanical integrity and electrochemical performance in binders for lithium-ion batteries is one of the many challenges of improving capacity and performance. In this paper, we demonstrate a self-doped conjugated polymer, poly(9,9-bis(4′-sulfonatobutyl)fluorene-alt-co-1,4-phenylene) (PFP), which not only provides mechanical robustness but also improves electrode stability at temperatures as high as 450 °C. The self-doped PFP polymer is comprised of a conjugated polyfluorene backbone with sulfonate terminated side-chains that serve to dope the conjugated polymer backbone, resulting in stable conductivity. Composite electrodes are prepared by blending PFP with V₂O₅ in water, followed by casting and drying. Structural characterization with X-ray diffraction and wide-angle X-ray scattering shows that PFP suppresses the crystallization of V₂O₅ at high temperatures (up to 450 °C), resulting in improved electrode stability during cycling and improved rate performance. This study demonstrates the potential of self-doped conjugated polymers for use as polymeric binders to enhance mechanical, structural, and electrochemical properties.

Vanadium Pentoxide-Enwrapped Polydiphenylamine/Polyurethane Nanocomposite: High-Performance Anticorrosive Coating

Nanocomposite coatings with synergistic properties hold a potential in long-term corrosion protection for carbon steel. Polydiphenylamine (PDPA) and vanadium pentoxide (V₂O₅) have rarely been used as a corrosion inhibitor. Moreover, oleo polyurethanes are always demanded in the field of anticorrosive coatings. In view of this, we have synthesized safflower oil polyurethane (SFPU) and their nanocomposites using V₂O₅-enwrapped PDPA (V₂O₅-PDPA) as nanofiller. Fourier-transform infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis were used to characterize the structural, morphological, and thermal properties of these coatings. Corrosion resistance performance of these coatings in 5 wt % NaCl solution was determined by electrochemical measurements and salt spray tests. These studies exhibited very low I_corr (7.45 × 10^-11 A cm^-2), high E_corr (-0.04 V), impedance (1.69 × 10¹¹ Ω cm²), and phase angle (84°) after the exposure of 30 days. An immersion test, in 1 M H₂SO₄ solution for 24 h, was also performed to investigate the effect of oxidizing acid on the surface of coatings. These results revealed the superior anticorrosive activity of nanocomposite coatings compared to those of plain SFPU and other such reported systems. The superior anticorrosive property of the proposed nanocomposite coatings provides a new horizon in the development of high-performance anticorrosive coatings for various industries.

Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft-Polyurethane Composites

The self-healing ability can be imparted to the polymers by different mechanisms. In this study, self-healing polydimethylsiloxane-graft-polyurethane (PDMS-g-PUR)/Vanadium pentoxide (V₂O₅) nanofiber supramolecular polymer composites based on a reversible hydrogen bonding mechanism are prepared. V₂O₅ nanofibers are synthesized via colloidal route and characterized by XRD, SEM, EDX, and TEM techniques. In order to prepare PDMS-g-PUR, linear aliphatic PUR having one ⁻COOH functional group (PUR-COOH) is synthesized and grafted onto aminopropyl functionalized PDMS by EDC/HCl coupling reaction. PUR-COOH and PDMS-g-PUR are characterized by ¹H NMR, FTIR. PDMS-g-PUR/V₂O₅ nanofiber composites are prepared and characterized by DSC/TGA, FTIR, and tensile tests. The self-healing ability of PDMS-graft-PUR and composites are determined by mechanical tests and optical microscope. Tensile strength data obtained from mechanical tests show that healing efficiencies of PDMS-g-PUR increase with healing time and reach 85.4 ± 1.2 % after waiting 120 min at 50 °C. The addition of V₂O₅ nanofibers enhances the mechanical properties and healing efficiency of the PDMS-g-PUR. An increase of healing efficiency and max tensile strength from 85.4 ± 1.2% to 95.3 ± 0.4% and 113.08 ± 5.24 kPa to 1443.40 ± 8.96 kPa is observed after the addition of 10 wt % V₂O₅ nanofiber into the polymer.

Chemical Vapor-Deposited Vanadium Pentoxide Nanosheets with Highly Stable and Low Switching Voltages for Effective Selector Devices

Recently, attempts to overcome the physical limits of memory devices have led to the development of promising materials and architectures for next-generation memory technology. The selector device is one of the essential ingredients of high-density stacked memory systems. However, complicated constituent deposition conditions and thermal degradation are problematic, even with effective selector device materials. Herein, we demonstrate the highly stable and low-threshold voltages of vanadium pentoxide (V₂O₅) nanosheets synthesized by facile chemical vapor deposition, which have not been previously reported on the threshold switching (TS) properties. The electrons occupying trap sites in poly-crystalline V₂O₅ nanosheet contribute to the perfectly symmetric TS feature at the bias polarity and low-threshold voltages in V₂O₅, confirmed by high-resolution transmission electron microscopy measurements. Furthermore, we find an additional PdO interlayer in V₂O₅ nanodevices connected with a Pd/Au electrode after thermal annealing treatment. The PdO interlayer decreases the threshold voltages, and the I_on/ I_off ratio increases because of the increased trap density of V₂O₅. These studies provide insights into V₂O₅ switching characteristics, which can support low power consumption in nonvolatile memory devices.

V₂O₅ Thin Films as Nitrogen Dioxide Sensors †

Vanadium pentoxide thin films were deposited onto insulating support by means of rf reactive sputtering from a metallic vanadium target. Argon-oxygen gas mixtures of different compositions controlled by the flow rates were used for sputtering. X-ray diffraction at glancing incidence (GIXD) and Scanning Electronic Microscopy (SEM) were used for structural and phase characterization. Thickness of the films was determined by the profilometry. It has been confirmed by GIXD that the deposited films are composed of V₂O₅ phase. The gas sensing properties of V₂O₅ thin films were investigated at temperatures from range 410⁻617 K upon NO₂ gas of 4⁻20 ppm. The investigated material exhibited good response and reversibility towards nitrogen dioxide. The effect of metal-insulator transition (MIT) on sensor performance has been observed and discussed for the first time. It was found that a considerable increase of the sensor sensitivity occured above 545 K, which is related to postulated metal-insulator transition.

Rational Design of Hierarchical Titanium Nitride@Vanadium Pentoxide Core-Shell Heterostructure Fibrous Electrodes for High-Performance 1.6 V Nonpolarity Wearable Supercapacitors

Extensive progress has been made in fiber-shaped asymmetric supercapacitors (FASCs) for portable and wearable electronics. However, positive and negative electrodes must be distinguished and low energy densities are a crucial challenge and thus limit their practical applications. This paper reports an efficient method to directly grow TiN nanowire arrays@V₂O₅ nanosheets core-shell heterostructures on carbon nanotube fibers as nonpolarity electrodes. Benefiting from their unique heterostructure, single electrodes possess high specific capacitances of 195.1 and 230.7 F cm^-3 as positive and negative electrodes, respectively. Furthermore, all-solid-state nonpolarity FASC devices with a maximum voltage of 1.6 V were successfully fabricated. Our devices achieve an outstanding specific capacitance of 74.25 F cm^-3 and a remarkable energy density of 26.42 mW h cm^-3. More importantly, their electrochemical performance changed negligibly regardless of whether the charge-discharge process is in positive or negative direction, indicating excellent nonpolarity. Therefore, these high-performance nonpolarity FASCs pave the way for next-generation wearable energy storage devices.

A Hydrogel of Ultrathin Pure Polyaniline Nanofibers: Oxidant-Templating Preparation and Supercapacitor Application

Although challenging, fabrication of porous conducting polymeric materials with excellent electronic properties is crucial for many applications. We developed a fast in situ polymerization approach to pure polyaniline (PANI) hydrogels, with vanadium pentoxide hydrate nanowires as both the oxidant and sacrifice template. A network comprised of ultrathin PANI nanofibers was generated during the in situ polymerization, and the large aspect ratio of these PANI nanofibers allowed the formation of hydrogels at a low solid content of 1.03 wt %. Owing to the ultrathin fibril structure, PANI hydrogels functioning as a supercapacitor electrode display a high specific capacitance of 636 F g^-1, a rate capability, and good cycling stability (∼83% capacitance retention after 10,000 cycles). This method was also extended to the preparation of polypyrrole and poly(3,4-ethylenedioxythiophene) hydrogels. This template polymerization method represents a rational strategy for design of conducing polymer networks, which can be readily integrated in high-performance devices or a further platform for functional composites.

Real-time Analysis of Impedance Alterations by the Effects of Vanadium Pentoxide on Several Carcinoma Cell Lines

Objectives

Vanadium compounds have various pharmacologic effects and all available evidence reveals that the effects of vanadium compounds depend on many factors, mainly on the type of cells and dose. The proapoptotic or antiapoptotic effect of vanadium compounds depends strongly on the cell type.

Materials and Methods

In this study, the effects of vanadium pentoxide (V₂O₅) were investigated using several tumor cell lines: a colorectal cancer cell line (Colo-205), a human breast adenocarcinoma cell line (MCF-7), and a normal human fibroblast cell line. Five different concentrations of V₂O₅ between 25-200 µM were applied on the cells and xCELLigence real-time cell analysis was conducted to evaluate the impedance alterations. This study is the first to show V₂O₅'s effects on Colo-205 and MCF-7 and human fibroblast cell lines in a real-time manner.

Results

In the Colo-205 cell line, cell index (CI) alterations decreased slightly at 25 µM and 50 µM, and increased at 100 µM, 150 µM and 200 µM concentrations. In the MCF-7 cell line, CI alterations increased at all concentrations compared with the untreated control. However, in the healthy fibroblast cell line, the CI alterations decreased at all concentrations compared with the untreated control, which limits the use of V₂O₅ for its cytotoxic effect in vivo.

Conclusion

The combination of conventional anticancer drugs can be used to increase the effectiveness and reduce the adverse effects of these drugs considering stages of cancer and cancer type. Our results suggest that V₂O₅ has disparate effects on several cancer cells at different concentrations.

Zn/V2O5 Aqueous Hybrid-Ion Battery with High Voltage Platform and Long Cycle Life

Aqueous zinc-ion batteries attract increasing attention due to their low cost, high safety, and potential application in stationary energy storage. However, the simultaneous realization of high cycling stability and high energy density remains a major challenge. To tackle the above-mentioned challenge, we develop a novel Zn/V₂O₅ rechargeable aqueous hybrid-ion battery system by using porous V₂O₅ as the cathode and metallic zinc as the anode. The V₂O₅ cathode delivers a high discharge capacity of 238 mAh g^-1 at 50 mA g^-1. 80% of the initial discharge capacity can be retained after 2000 cycles at a high current density of 2000 mA g^-1. Meanwhile, the application of a "water-in-salt" electrolyte results in the increase of discharge platform from 0.6 to 1.0 V. This work provides an effective strategy to simultaneously enhance the energy density and cycling stability of aqueous zinc ion-based batteries.

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.

Tunable Mechanochemistry of Lithium Battery Electrodes

The interplay between mechanical strains and battery electrochemistry, or the tunable mechanochemistry of batteries, remains an emerging research area with limited experimental progress. In this report, we demonstrate how elastic strains applied to vanadium pentoxide (V₂O₅), a widely studied cathode material for Li-ion batteries, can modulate the kinetics and energetics of lithium-ion intercalation. We utilize atomic layer deposition to coat V₂O₅ materials onto the surface of a shapememory superelastic NiTi alloy, which allows electrochemical assessment at a fixed and measurable level of elastic strain imposed on the V₂O₅, with strain state assessed through Raman spectroscopy and X-ray diffraction. Our results indicate modulation of electrochemical intercalation potentials by ∼40 mV and an increase of the diffusion coefficient of lithium ions by up to 2.5-times with elastic prestrains of <2% imposed on the V₂O₅. These results are supported by density functional theory calculations and demonstrate how mechanics of nanomaterials can be used as a precise tool to strain engineer the electrochemical energy storage performance of battery materials.

Heterogeneous TiO2/V2O5/Carbon Nanotube Electrodes for Lithium-Ion Batteries

Vanadium pentoxide (V₂O₅) is proposed and investigated as a cathode material for lithium-ion (Li-ion) batteries. However, the dissolution of V₂O₅ during the charge/discharge remains as an issue at the V₂O₅-electrolyte interface. In this work, we present a heterogeneous nanostructure with carbon nanotubes supported V₂O₅/titanium dioxide (TiO₂) multilayers as electrodes for thin-film Li-ion batteries. Atomic layer deposition of V₂O₅ on carbon nanotubes provides enhanced Li storage capacity and high rate performance. An additional TiO₂ layer leads to increased morphological stability and in return higher electrochemical cycling performance of V₂O₅/carbon nanotubes. The physical and chemical properties of TiO₂/V₂O₅/carbon nanotubes are characterized by cyclic voltammetry and charge/discharge measurements as well as electron microscopy. The detailed mechanism of the protective TiO₂ layer to improve the electrochemical cycling stability of the V₂O₅ is unveiled.

Polysulfide Anchoring Mechanism Revealed by Atomic Layer Deposition of V2O5 and Sulfur-Filled Carbon Nanotubes for Lithium-Sulfur Batteries

Despite the promise of surface engineering to address the challenge of polysulfide shuttling in sulfur-carbon composite cathodes, melt infiltration techniques limit mechanistic studies correlating engineered surfaces and polysulfide anchoring. Here, we present a controlled experimental demonstration of polysulfide anchoring using vapor phase isothermal processing to fill the interior of carbon nanotubes (CNTs) after assembly into binder-free electrodes and atomic layer deposition (ALD) coating of polar V₂O₅ anchoring layers on the CNT surfaces. The ultrathin submonolayer V₂O₅ coating on the CNT exterior surface balances the adverse effect of polysulfide shuttling with the necessity for high sulfur utilization due to binding sites near the conductive CNT surface. The sulfur loaded into the CNT interior provides a spatially separated control volume enabling high sulfur loading with direct sulfur-CNT electrical contact for efficient sulfur conversion. By controlling ALD coating thickness, high initial discharge capacity of 1209 mAh/g_S at 0.1 C and exceptional cycling at 0.2 C with 87% capacity retention after 100 cycles and 73% at 450 cycles is achieved and correlated to an optimal V₂O₅ anchoring layer thickness. This provides experimental evidence that surface engineering approaches can be effective to overcome polysulfide shuttling by controlled design of molecular-scale building blocks for efficient binder free lithium sulfur battery cathodes.

Suppressing Self-Discharge and Shuttle Effect of Lithium-Sulfur Batteries with V2 O5 -Decorated Carbon Nanofiber Interlayer

V₂ O₅ decorated carbon nanofibers (CNFs) are prepared and used as a multifunctional interlayer for a lithium-sulfur (Li-S) battery. V₂ O₅ anchored on CNFs can not only suppress the shuttle effect of polysulfide by the strong adsorption and redox reaction, but also work as a high-potential dam to restrain the self-discharge behavior in the battery. As a result, Li-S batteries with a high capacity and long cycling life can be stored and rested for a long time without obvious capacity fading.

Atomic Layer Deposition of Ultrathin Crystalline Epitaxial Films of V2O5

Ultrathin epitaxial films (10-90 nm thick) of V₂O₅ have been grown on c-Al₂O₃ by atomic layer deposition using vanadyl acetylacetonate as the vanadium precursor along with oxygen plasma. Various process parameters have been optimized for the purpose, and excellent crystalline films could be obtained below 200 °C, without the need for post-heat treatment. With a moderate temperature window, the process yields a growth rate of 0.45 Å/cycle. The films have been characterized by electron microscopy, atomic force microscopy, Raman spectroscopy, and other means. The films exhibit a (001) preferred orientation with respect to c-Al₂O₃ and undergo compressive strain at the initial few monolayer growth to adjust epitaxially with the substrate. Heterojunction diodes based on TiO₂(p)-(n)V₂O₅ as well as a humidity sensor have been fabricated using the V₂O₅ films.

Facile Synthesis of V₂O₅ Hollow Spheres as Advanced Cathodes for High-Performance Lithium-Ion Batteries

Three-dimensional V₂O₅ hollow structures have been prepared through a simple synthesis strategy combining solvothermal treatment and a subsequent thermal annealing. The V₂O₅ materials are composed of microspheres 2–3 μm in diameter and with a distinct hollow interior. The as-synthesized V₂O₅ hollow microspheres, when evaluated as a cathode material for lithium-ion batteries, can deliver a specific capacity as high as 273 mAh·g⁻¹ at 0.2 C. Benefiting from the hollow structures that afford fast electrolyte transport and volume accommodation, the V₂O₅ cathode also exhibits a superior rate capability and excellent cycling stability. The good Li-ion storage performance demonstrates the great potential of this unique V₂O₅ hollow material as a high-performance cathode for lithium-ion batteries.

Conducting Block Copolymer Binders for Carbon-Free Hybrid Vanadium Pentoxide Cathodes with Enhanced Performance

Polymeric binders are essential to battery electrodes, mechanically stabilizing the active materials. Most often, these binders are insulating, and conductive carbons must be added to the electrode structure. Conductive polymer binders, those that transport both ions and electrons, are of primary interest because they potentially eliminate the need for carbon additives. However, it is challenging to incorporate both ion- and electron-conductive polymeric binders into electrode systems because of differences in physical affinities among the two polymer types and the electroactive material. Here, we investigate amphiphilic polymeric binders comprised of electron- and ion-conducting poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) as compared to P3HT, PEO, and a blend of P3HT/PEO homopolymers in carbon-free V₂O₅ cathodes. The electrode with P3HT-b-PEO binder has the highest capacity of 190 mAh/g, whereas V₂O₅ is only 77 mAh/g at a C rate of 0.1 after over 200 cycles: a 2.5-fold improvement. Similarly P3HT, PEO, and the blend have capacities of 139, 130, and 70 mAh/g, which are not nearly as impressive as the block copolymer binder. The unique architecture of P3HT-b-PEO, wherein P3HT and PEO blocks are covalently bonded, promotes the uniform distribution of conductive binders within the V₂O₅ structure, whereas the analogous P3HT/PEO blend suffers from phase separation. This work demonstrates that conductive block copolymer binders enable carbon-free electrodes for lithium-ion battery systems.

Impacts of Surface Energy on Lithium Ion Intercalation Properties of V2O5

Oxygen vacancies have demonstrated to be one of the most effective ways to alter electrochemical performance of electrodes for lithium ion batteries, though there is little information how oxygen vacancies affect the electrochemical properties. Vanadium pentoxide (V2O5) cathode has been investigated to explore the relationship among oxygen vacancies, surface energy, and electrochemical properties. The hydrogen-treated V2O5 (H-V2O5) sample synthesized via thermal treatment under H2 atmosphere possesses a high surface energy (63 mJ m(-2)) as compared to that of pristine V2O5 (40 mJ m(-2)) and delivers a high reversible capacity of 273.4 mAh g(-1) at a current density of 50 mA g(-1), retaining 189.0 mAh g(-1) when the current density increases to 2 A g(-1). It also displays a capacity retention of 92% after 100 cycles at 150 mA g(-1). The presence of surface oxygen vacancies increases surface energy and possibly serves as a nucleation center to facilitate phase transition during lithium ion intercalation and deintercalation processes.

Vanadium Pentoxide Nanobelt-Reduced Graphene Oxide Nanosheet Composites as High-Performance Pseudocapacitive Electrodes: ac Impedance Spectroscopy Data Modeling and Theoretical Calculations

Graphene nanosheets and graphene nanoribbons, G combined with vanadium pentoxide (VO) nanobelts (VNBs) and VNBs forming GVNB composites with varying compositions were synthesized via a one-step low temperature facile hydrothermal decomposition method as high-performance electrochemical pseudocapacitive electrodes. VNBs from vanadium pentoxides (VO) are formed in the presence of graphene oxide (GO), a mild oxidant, which transforms into reduced GO (rGO_HT), assisting in enhancing the electronic conductivity coupled with the mechanical robustness of VNBs. From electron microscopy, surface sensitive spectroscopy and other complementary structural characterization, hydrothermally-produced rGO nanosheets/nanoribbons are decorated with and inserted within the VNBs’ layered crystal structure, which further confirmed the enhanced electronic conductivity of VNBs. Following the electrochemical properties of GVNBs being investigated, the specific capacitance C_sp is determined from cyclic voltammetry (CV) with a varying scan rate and galvanostatic charging-discharging (V–t) profiles with varying current density. The rGO-rich composite V₁G₃ (i.e., VO/GO = 1:3) showed superior specific capacitance followed by VO-rich composite V₃G₁ (VO/GO = 3:1), as compared to V₁G₁ (VO/GO = 1:1) composite, besides the constituents, i.e., rGO, rGO_HT and VNBs. Composites V₁G₃ and V₃G₁ also showed excellent cyclic stability and a capacitance retention of >80% after 500 cycles at the highest specific current density. Furthermore, by performing extensive simulations and modeling of electrochemical impedance spectroscopy data, we determined various circuit parameters, including charge transfer and solution resistance, double layer and low frequency capacitance, Warburg impedance and the constant phase element. The detailed analyses provided greater insights into physical-chemical processes occurring at the electrode-electrolyte interface and highlighted the comparative performance of thin heterogeneous composite electrodes. We attribute the superior performance to the open graphene topological network being beneficial to available ion diffusion sites and the faster transport kinetics having a larger accessible geometric surface area and synergistic integration with optimal nanostructured VO loading. Computational simulations via periodic density functional theory (DFT) with and without V₂O₅ adatoms on graphene sheets are also performed. These calculations determine the total and partial electronic density of state (DOS) in the vicinity of the Fermi level (i.e., higher electroactive sites), in turn complementing the experimental results toward surface/interfacial charge transfer on heterogeneous electrodes.

Ultrathin Nanotube/Nanowire Electrodes by Spin-Spray Layer-by-Layer Assembly: A Concept for Transparent Energy Storage

Fully integrated transparent devices require versatile architectures for energy storage, yet typical battery electrodes are thick (20-100 μm) and composed of optically absorbent materials. Reducing the length scale of active materials, assembling them with a controllable method and minimizing electrode thickness should bring transparent batteries closer to reality. In this work, the rapid and controllable spin-spray layer-by-layer (SSLbL) method is used to generate high quality networks of 1D nanomaterials: single-walled carbon nanotubes (SWNT) and vanadium pentoxide (V2O5) nanowires for anode and cathode electrodes, respectively. These ultrathin films, deposited with ∼2 nm/bilayer precision are transparent when deposited on a transparent substrate (>87% transmittance) and electrochemically active in Li-ion cells. SSLbL-assembled ultrathin SWNT anodes and V2O5 cathodes exhibit reversible lithiation capacities of 23 and 7 μAh/cm(2), respectively at a current density of 5 μA/cm(2). When these electrodes are combined in a full cell, they retain ∼5 μAh/cm(2) capacity over 100 cycles, equivalent to the prelithiation capacity of the limiting V2O5 cathode. The SSLbL technique employed here to generate functional thin films is uniquely suited to the generation of transparent electrodes and offers a compelling path to realize the potential of fully integrated transparent devices.

Vanadium pentoxide prevents NK-92MI cell proliferation and IFNγ secretion through sustained JAK3 phosphorylation

Vanadium is a major air pollutant with toxic and carcinogenic effects; it also exercises immunosuppressive effects on the adaptive immune response. Its effect on the innate immune response is poorly explored. The aim of this study was to identify if vanadium pentoxide (V2O5) impairs the function of immunoregulatory NK cells and to determine possible mechanisms associated with this effect. Interleukin-2-independent NK-92MI cells were exposed to different V2O5 concentrations for 6, 12, or 24 h periods. Cell proliferation was then evaluated using CFSE staining, apoptosis by Annexin V binding, and necrosis by 7-AAD staining. The release of IL-2, -4, -6, -10, -17A, IFNγ, and TNFα by the cells were assessed using a human CBA kit. Expression of CD45, SOCS1, JAK3, pJAK3, STAT5, pSTAT5, IL-2R, IL-15R, Fas, and FasL in/on the cells was determined by flow cytometry; JAK3 and pJAK3 expression were also evaluated via confocal microscopy. The results indicated that V2O5 could inhibit NK-92MI cell proliferation and induce cell apoptosis in a dose- and time-related manner. V2O5 also inhibited IL-2, IL-10, and IFNγ secretion but mostly only after 24 h of exposure and with primarily the higher doses tested. V2O5 had no effect on expression of JAK3 and STAT5, but did cause an increase in pJAK3 and appeared to lead (trend) to reductions in levels of phosphorylated STAT5. V2O5 increased the expression of IL-2R, IL-15R, Fas, and FasL at concentrations above the 50-100 µM range. V2O5 had no effect on expression of the CD45 membrane phosphatase, but it did cause an increase in the expression of SOCS1. These results indicate that a key toxic effect of V2O5 on NK cells is a dysregulation of signaling pathways mediated by IL-2. These effects could help to explain the previously-reported deleterious effects on innate immune responses of hosts exposed to inhaled V2O5.

A V2O5/conductive-polymer core/shell nanobelt array on three-dimensional graphite foam: a high-rate, ultrastable, and freestanding cathode for lithium-ion batteries

A thin polymer shell helps V2O5 a lot. Short V2O5 nanobelts are grown directly on 3D graphite foam as a lithium-ion battery (LIB) cathode material. A further coating of a poly(3,4-ethylenedioxythiophene) (PEDOT) thin shell is the key to the high performance. An excellent high-rate capability and ultrastable cycling up to 1000 cycles are demonstrated.

Photoconductivities in monocrystalline layered V2O5 nanowires grown by physical vapor deposition

Photoconductivities of monocrystalline vanadium pentoxide (V2O5) nanowires (NWs) with layered orthorhombic structure grown by physical vapor deposition (PVD) have been investigated from the points of view of device and material. Optimal responsivity and gain for single-NW photodetector are at 7,900 A W-1 and 30,000, respectively. Intrinsic photoconduction (PC) efficiency (i.e., normalized gain) of the PVD-grown V2O5 NWs is two orders of magnitude higher than that of the V2O5 counterpart prepared by hydrothermal approach. In addition, bulk and surface-controlled PC mechanisms have been observed respectively by above- and below-bandgap excitations. The coexistence of hole trapping and oxygen sensitization effects in this layered V2O5 nanostructure is proposed, which is different from conventional metal oxide systems, such as ZnO, SnO2, TiO2, and WO3.