Pentoxide Nanowires Research Articles

Vanadium pentoxide nanowires preparation via kinetic control of vanadium oxytrichloride catalytic oxidation with APCVD

Vanadium pentoxide nanowires were successfully fabricated using vanadium oxytrichloride oxidation with copper oxide nanoparticles serving as catalysts via atmospheric pressure chemical vapor deposition. Kinetic parameters such as temperature and flow velocity were proved to play important roles in the morphologic control of as-deposited product. Vanadium pentoxide nanowires with an average length of ∼10 μm and a diameter of 50–100 nm, were obtained under the optimum conditions. A root growth mechanism of nanowires was proposed that precursor was readily captured by catalyst nanoparticles at the beginning of deposition, forming nucleation sites. Subsequently, the anisotropic growth of vanadium pentoxide is primarily governed by energy minimization under the reaction rate limited conditions. The presence of oxygen vacancies in the nanowires was confirmed by Raman, XPS and photoluminescence characterization, indicating promising applications in functional materials manufacture. The novel route for preparing vanadium pentoxide nanowires provides an alternative pathway for transitioning traditional vanadium industry towards advanced functional materials development.

Air-Working Electrochromic Artificial Muscles.

Artificial muscles are indispensable components for next-generation robotics to mimic the sophisticated movements of living systems and provide higher output energies when compared with real muscles. However, artificial muscles actuated by electrochemical ion injection have problems with single actuation properties and difficulties in stable operation in air. Here, air-working electrochromic artificial muscles (EAMs) with both color-changing and actuation functions are reported, which are constructed based on vanadium pentoxide nanowires and carbon tube yarn. Each EAM can generate a contractile stroke of ≈12% during stable operation in the air with multiple color changes (yellow-green-gray) under ±4V actuation voltages. The reflectance contrast is as high as 51%, demonstrating the excellent versatility of the EAMs. In addition, a torroidal EAM arrangement with fast response and high resilience is constructed. The EAM's contractile stroke can be displayed through visual color changes, which provides new ideas for future artificial muscle applications in soft robots and artificial limbs.

Photoelectrodes based on selenium-polypyrrole-vanadium pentoxide nanowire films for high-performance lightweight symmetric photo-supercapacitors: A flexible photo-rechargeable electrical energy storage device

V2O5-PPy, Se-V2O5, and Se-V2O5-PPy films on flexible indium tin oxide electrodes have been used to prepare flexible, lightweight and high-performance flexible photo-supercapacitors. Vanadium pentoxide (V2O5) nanowires, which are excellent electrode compounds for high electrochemical performance and long cycle life photoresponsive supercapacitance, have been synthesized and their photo-assisted supercapacitor performances have been enhanced by selenium and polypyrrole (PPy). The capacitive performances of Se-V2O5-PPy have been improved to 375 mF/cm2 at 0.25 mA.cm−2, which is over 2.1 times that of pure V2O5, 1.5 times those of the corresponding values for V2O5-PPy, 1.6 times of Se-V2O5 and 1.7 times of Se-PPy at identical current densities. Areal capacitance values of 151 mF/cm2 and 375 mF/cm2 (@ 0.25 mA/cm2) have been shown by Se-V2O5-PPy electrodes prepared in the dark and under light irradiation, respectively. Good cycle stability of 91% is shown by the assembled device after 10,000 cycles and its voltage window can be increased to 2.0 V. Furthermore, maximum volumetric energy densities of 16.8 and 41.6 Wh/kg can be obtained in the dark and under light irradiation, respectively. The flexible self-powered photo-supercapacitors show remarkable flexibility while maintaining their supercapacitor performance well even under various bent conditions, which signifies the outstanding flexibility of this device.

Ethanol-Induced Ni2+ -Intercalated Cobalt Organic Frameworks on Vanadium Pentoxide for Synergistically Enhancing the Performance of 3D-Printed Micro-Supercapacitors.

The synthesis of metal-organic framework (MOF) nanocomposites with high energy density and excellent mechanical strength is limited by the degree of lattice matching and crystal surface structure. In this study, dodecahedral ZIF-67 is synthesized uniformly on vanadium pentoxide nanowires. The influence of the coordination mode on the surface of ZIF-67 in ethanol is also investigated. Benefitting from the different coordination abilities of Ni2+ , Co2+ , and N atoms, spatially separated surface-active sites are created through metal-ion exchange. Furthermore, the incompatibility between the d8 electronic configuration of Ni2+ and the three-dimensional (3D) structure of ZIF-67 afforded the synthesis of hollow structures by controlling the amount of Ni doping. The formation of NiCo-MOF@CoOOH@V2 O5 nanocomposites is confirmed using X-ray absorption fine structure analysis. The high performance of the obtained composite is illustrated by fabricating a 3D-printed micro-supercapacitor, exhibiting a high area specific capacitance of 585 mF cm-2 and energy density of 159.23 µWh cm-2 (at power density = 0.34mW cm-2 ). The solvent/coordination tuning strategy demonstrated in this study provides a new direction for the synthesis of high-performance nanomaterials for electrochemical energy storage applications.

V2O5 Nanowires-Coated Yarn-Based Temperature Sensor With Wireless Data Transfer for Smart Textiles

Smart textile with capabilities to sense different stimuli like temperature, pressure etc. are of considerable interest in applications such as sports, fashion, healthcare and robotics etc. The seamless integration of various sensors is desired for effective use of smart textiles in these applications. To this end, here, we present a yarn based wireless temperature sensor developed by modifying a P(VDF-TrFE) coated stainless steel yarn with vanadium pentoxide (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> ) nanowires (NWs). The current-voltage (I-V) characteristics and the temperature sensing performance of the devices are evaluated between 5-50°C with a step increase of 5°C. The unpacked device exhibits a sensitivity of 3.7 %/°C with a response time of 9s. The device is encapsulated with nanosilica/epoxy polymeric layer and its influence on sensors performance is also analyzed. After encapsulation, the device showed more linear response, but with slightly reduced sensitivity of 2.18 %/°C. Moreover, the effect of mechanical bending cycles on sensing performance of packaged device is studied. The sensor showed linear response even after 2000 bending cycles, but sensitivity was reduced to 1.257%/°C. Finally, the temperature sensor data is wirelessly transferred to demonstrate the potential use of developed sensors in above applications.

A cascade nanozyme with antimicrobial effects against nontypeable Haemophilus influenzae.

Otitis media (OM) is the main cause of pediatric antibiotic prescriptions. Nontypeable Haemophilus influenzae (NTHi) is a major OM pathogen, which forms a biofilm that resists conventional antimicrobials and immune clearance. Thus, novel treatments that are effective against NTHi and its biofilm are urgently required. Nanozymes (often inorganic nanoparticles) mimic natural enzymes' catalytic activities to generate strong antimicrobials at the site of infection, and thus represent one of the emerging solutions to the crisis of antimicrobial resistance. They mimic natural enzymes' activities, such as generating strong antimicrobials catalytically at the site of infection, to minimize overexposure. However, that in situ generation often relies on Reactive Oxygen Species (ROS) as precursors, a prerequisite that limits the broad deployment of nanozymes. To address this challenge, we designed a cascade nanozyme that generates an antiseptic, HOBr, from a ubiquitous non-ROS, i.e., O2, which successfully eradicates NTHi. The cascade nanozyme simultaneously exhibits glucose oxidase (GOx)-like activity from gold nanoparticles (AuNPs) and haloperoxidase (HPO)-mimicking activity from vanadium pentoxide nanowires (V2O5 NWs) connected using dopamine (DPA). The cascade nanozyme demonstrated strong antimicrobial efficacy against NTHi and its biofilm, while showing improved biocompatibility compared to the nanozyme of V2O5 NWs alone. The cascade nanozyme thus points to a material-oriented infectious disease treatment strategy, where small-molecule antimicrobials are generated in real time at the site of infection for the benefit of autonomous dosing. This strategy potentially mitigates the development of antimicrobial resistance and reduces side effects.

On-demand synthesis of antiseptics at the site of infection for treatment of otitis media

Otitis media (OM) is the main reason for pediatric antibiotic prescriptions. The current treatment mandates a rigorous regimen of multidose antibiotics over 5–10 days. The systemic antibiotic exposure and often prematurely terminated treatment due to the challenge of drug administration to young patients are believed to breed antibiotic resistance. To address these challenges, we designed a local treatment that converted a metabolic product (H2O2) of an OM pathogen (Streptococcus pneumoniae) into a potent antiseptic (HOBr), a reaction catalyzed by locally administered vanadium pentoxide nanowires. The therapeutic, HOBr, was only synthesized in the presence of the pathogen, enabling on-demand generation of therapeutics for OM treatment. Hypohalous acids are broad-spectrum and have a long history in general disinfection applications without breeding substantial drug resistance. A single dose of the nanowire formulation eradicated OM in a standard chinchilla model in 7 days with no observable tissue toxicity or negative impact on hearing sensitivity.

Ordered porous and uniform electric-field-strength micro-supercapacitors by 3D printing based on liquid-crystal V2O5 nanowires compositing carbon nanomaterials

The design of electrode internal structure plays an important role in improving the performance of micro-supercapacitors (MSCs). However, the complexity of the program hinders the development and application of Three-dimensional(3D)-printed MSCs. Herein, printable inks were prepared by using vanadium pentoxide nanowires as active materials, carbon nanotubes as collector and conductive agent, graphene oxide as adhesive, scaffold and water retaining agent. Benefiting from the liquid–crystal properties of materials and 3D printing technology as well as the adjustment of the materials proportion, onion-like structures with ordered porous layered structure and uniform electric-field-strength MSCs were constructed. The 3D-printed MSC has fine area capacitance (34.68 mF cm−2) and area energy density (1.73 µWh cm−2 at a current density of 0.24 mA cm−2). Therefore, using the unique characteristics of materials to build an efficient 3D printing strategy is expected to provide a feasible solution for the construction of various MSCs and other high-energy storage systems.

A conjugated polymer with Electron-withdrawing cyano group enables for flexible asymmetric electrochromic supercapacitors

Flexible electrochromic supercapacitors (ECSCs) consisting of conjugated polymer electrodes are promising for integrating optical modulation with sustainable energy storage. However, there remain formidable challenges to achieving long-term cycling stability while maximizing high device output voltage. Here, we design a new twisted conjugated polymer bearing dual-redox centers (thiophene and triphenylamine) and an electron-withdrawing cyano group. The as-prepared conjugated polymer showcases elevated discharge potential and highly efficient charge transport synchronously, attributed to the lowered energy of the lowest unoccupied molecular (LUMO) orbitals and twisted alignment of the polymer chain. Coupled with the transparent vanadium pentoxide (V2O5) nanowires ion-storage material, the flexible ECSC affords a high optical contrast of 67 %, wide voltage window of 2 V, large capacitance of 32.9 mF/cm2, and outstanding cycling durability (86 % capacitance and 96 % optical modulation retention after 7000 cycles at 0.2 mA/cm2). This molecular engineering strategy and insight illustrated by density functional theory (DFT) calculation together with electrochemical kinetics analysis provide another way along the route toward the synergetic improvement of electrochromic and energy storage performance.

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.

A deep learned nanowire segmentation model using synthetic data augmentation

Automated particle segmentation and feature analysis of experimental image data are indispensable for data-driven material science. Deep learning-based image segmentation algorithms are promising techniques to achieve this goal but are challenging to use due to the acquisition of a large number of training images. In the present work, synthetic images are applied, resembling the experimental images in terms of geometrical and visual features, to train the state-of-art Mask region-based convolutional neural networks to segment vanadium pentoxide nanowires, a cathode material within optical density-based images acquired using spectromicroscopy. The results demonstrate the instance segmentation power in real optical intensity-based spectromicroscopy images of complex nanowires in overlapped networks and provide reliable statistical information. The model can further be used to segment nanowires in scanning electron microscopy images, which are fundamentally different from the training dataset known to the model. The proposed methodology can be extended to any optical intensity-based images of variable particle morphology, material class, and beyond.

Correlation between the Dielectric Response and Thickness of Vanadium Pentoxide Nanowires

Correlation between the Dielectric Response and Thickness of Vanadium Pentoxide Nanowires

Single-layered assembly of vanadium pentoxide nanowires on graphene for nanowire-based lithography technique

Graphene nanoribbon (GNR)-based materials are a promising device material because of their potential high carrier mobility and atomically thin structure. Various approaches have been reported for preparing the GNR-based materials, from bottom-up chemical synthetic procedures to top-down fabrication techniques using lithography of graphene. However, it is still difficult to prepare a large-scale GNR-based material. Here, we develop a procedure to prepare a large-scale GNR network using networked single-layer inorganic nanowires. Vanadium pentoxide (V2O5) nanowires were assembled on graphene with an interfacial layer of a cationic polymer via electrostatic interaction. A large-scale nanowire network can be prepared on graphene and is stable enough for applying an oxygen plasma. Using plasma etching, a networked graphene structure can be generated. Removing the nanowires results in a networked flat structure whose both surface morphology and Raman spectrum indicate a GNR networked structure. The field-effect device indicates the semiconducting character of the GNR networked structure. This work would be useful for fabricating a large-scale GNR-based material as a platform for GNR junctions for physics and electronic circuits.

Elastic Behavior of Nb2O5/Al2O3 Core-Shell Nanowires in Terms of Short-Range-Order Structures.

Single-crystalline niobium pentoxide nanowires (NWs) of length 10-15 μm and diameter 100-200 nm are synthesized by thermal oxidation of niobium substrates in a mild vacuum (3-10 mbar). Amorphous Al2O3 shells of varying thicknesses (10, 30, 40, and 50 nm) are deposited on top of the wires using atomic layer deposition. Bending tests of the uncoated Nb2O5 NWs and the Nb2O5/Al2O3 core-shell NWs are carried out inside a scanning electron microscope using a micromanipulator with a force measurement tip. The experimental deflection curves are modeled with Euler-Bernoulli (E-B) beam theory, and the Young's modulus is manipulated to determine the best fit. The Nb2O5 NWs with no shell are determined to have a Young's modulus of 67 ± 10 GPa, which agrees with the published data on Nb2O5 thin films. For core-shell NWs, only small deflections of the wires with 10 and 30 nm thick shells can be fitted with the E-B model when utilizing constant Young's modulus values of 67 GPa for the Nb2O5 core and about 160 GPa for the Al2O3 shell. When allowing for a change in the Young's modulus of the Al2O3 shell, the Young's modulus is determined to be at 120 ± 10 GPa for 10 nm and 145 ± 12 GPa for 30 nm at the highest applied load. For thicknesses of 40 nm and 50 nm, we observed a reduced but constant 120 ± 11 and 111 ± 10 GPa, respectively. Such behavior may result from structural disordering of the amorphous Al2O3 through reducing fractions of the densely packed polyhedra, while the fractions of the loosely packed polyhedra increase as a result of the increasing strain or the fabrication process. The increased disorder is associated with increased average interatomic spacing. Thus, the atomic bonding force and also the Young's modulus decrease.

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.

Efficient synthesis of niobium pentoxide nanowires and application in ethanolysis of furfuryl alcohol.

Nb2O5 nanowires with high specific surface area and crystallinity were prepared by using ammonium oxalate and an acetic acid solvent system. The nanomaterial was applied in ethanolysis of furfuryl alcohol (FA), and the yield of the product, 2-(ethoxymethyl)furan (FEE), achieved was up to 79.6%. Compared to mesoporous Nb2O5 materials and other porous materials, the residence time of FEE on the surface of the catalyst is shorter, and the yield of ethyl levulinate (EL) is lower. Furthermore, a high temperature calcination treatment can change the acid sites and acidity type distribution on the nanowire surface. By XRD, NH3-TPD, IR, and TG-DTA determination methods, it was found that the weak and medium-strong acid sites on the surface of Nb2O5 nanowires were reduced after a 300 °C treatment, and the amount of strong acid was relatively higher. According to the catalytic performance test data and acidity determination, it was concluded that more weak acid and medium-strong acid sites improve the conversion of furfuryl alcohol to FEE, and the strong acid sites promote further conversion of FEE to EL.

Interlaced nickel phosphide nanoflakes wrapped orthorhombic niobium pentoxide nanowires array for sustainable aqueous asymmetric supercapacitor

To obtain simple and cost-effective functional energy storage system at a practical level, a novel core-shell porous nanocomposite based on orthorhombic niobium pentoxide (T-Nb2O5) nanowires and metallic phosphides nanoflakes is reasonably designed and synthesized by a highly efficient solvothermal and subsequently moderate phosphorization procedure. The T-Nb2O5 nanowires act as structure-directing agent to directionally grow hierarchical ultrathin porous nickel phosphide (Ni2P) nanoflakes, thus providing high electrical conductivity, large surface area and sufficient redox active sites. Owing to the distinctive nanostructure and synergistic effects of the T-Nb2O5@Ni2P core-shell heterostructure, its electrochemical properties have vastly improved. When the current density is 1 A g−1, a high specific capacity of 105 mAh g−1 can be obtained. In addition, an asymmetric supercapacitor assembled based on the T-Nb2O5@Ni2P composite positive electrode and activated carbon negative electrode exhibits a high energy density of 30.2 Wh kg−1 at a power density of 453 W kg−1 and impressive cycling stability (90%) after 5000 cycles. The well-defined oxide/phosphide core-shell materials can be expected to a new type of electrode materials for the high-performance supercapacitors.

Zinc oxide/vanadium pentoxide heterostructures with enhanced day-night antibacterial activities

Low photocatalytic efficiency of visible light and fast recombination of photo-generated carriers are two challenges facing the applications of photocatalyst sterilant zinc oxide (ZnO). Meanwhile, both light and dark photocatalytic activities are important. It is of great theoretical and practical significance to construct a day-night photocatalytic antibacterial material, which is beneficial to the effective use of energy and to tackle the limitation of using photocatalytic bacteriostat. ZnO nanoflowers decorated vanadium pentoxide (V2O5) nanowires heterojunction (ZVH) was firstly fabricated using a facile water-bathing method. The designed ZVH structure efficiently produced abundant reactive oxygen species (ROS) in both light and darkness. It yielded 99.8% and 99.0% of antibacterial rate against S. aureus due to oxidative stress induced by ROS in light and darkness, respectively. The generation of ROS played a major role in the antibacterial activities against S. aureus under both light and dark conditions. The prepared ZVH with improved antibacterial properties provides an alternative for day-night antibacterial agents.

Microstructural and supercapacitive properties of one-dimensional vanadium pentoxide nanowires synthesized by hydrothermal method

Phase pure one-dimensional (1D) V2O5 nanowires (NWs) were synthesized by simple and cost-effective hydrothermal synthesis based on the reaction time varying from 10 to 50 h. The structural and surface morphology with elemental composition of the NWs was characterized through XRD, Raman and SEM, and TEM with EDX, respectively. The XRD and Raman studies exhibited that the obtained nanowires at reaction time of 35 h confirm orthorhombic V2O5 phase with predominant (001) orientation. SEM and TEM results show the 1D V2O5 NWs with 1D morphology and smooth surface with average diameter of 60 nm and length of several micrometers. The elemental composition was estimated from EDX spectrum. The 1D V2O5 NWs exhibited high specific capacitance of 702 F g−1 at current density of 1 mA cm−2 with excellent capacitance retention even after 1000 cycles.

Disodium citrate-assisted hydrothermal synthesis of V2O5 nanowires for high performance supercapacitors.

Orthorhombic vanadium pentoxide (V2O5) nanowires with uniform morphology were successfully fabricated via a facile hydrothermal process. The effect of disodium citrate dosage on the crystallinity, morphology and electrochemical properties of the products was analyzed. Experimental results indicate that orthorhombic V2O5 nanowires with high crystallinity and diameter of about 20 nm can be obtained at 180 °C for 24 h when the dosage of disodium citrate is 0.236 g. Furthermore, the prepared V2O5 nanowires demonstrate a high specific capacitance of 528.2 F g−1 at 0.5 A g−1 and capacitance retention of 85% after 1000 galvanostatic charge/discharge cycles at 1 A g−1 when used as supercapacitors electrode in 0.5 M K2SO4.