V2O5 Nanowires Research Articles

One-Dimensional V2O5/TiO2 Heterostructures for Chemiresistive Ozone Sensors

Over the last decades, there has been considerable interest in the synthesis of one-dimensional (1D) metal oxide nanostructures that can be used in gas sensor devices. Heterostructures, obtained by a combination of different semiconductor nanomaterials with different band energies, have been extensively studied in order to enhance their gas-sensing performance. In this context, our present study focuses on the investigation of chemiresistive-sensing capabilities of a combination of TiO2 nanoparticles and V2O5 nanowires obtained via hydrothermal treatment of the peroxo-metal complex. The formation of V2O5/TiO2 heterostructures was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. This study also proposes an efficient approach to produce 1D V2O5/TiO2 heterostructures with a good range of detection (0.09–1.25 ppm) and remarkable ozone-sensing properties related to repeatability and selectivity.

Enhancing the tribological properties of NiAl based nano-composites for aerospace bearing applications

The present work aims to extend the use of NiAl based nano-composites at different sliding conditions for aerospace bearing systems. A hybrid lubricant of V2O5 nano-wires and graphene nano-platelets (GNPs) has been used. NiAl + 5 wt% V2O5 nano-wires (NV) and NiAl + 5 wt% + 1.5 wt% GNPs (NVG) nano composites have been fabricated and tested. NVG nano-composites showed superior wear resistance at different sliding speeds at RT due to the self -healing properties of GNPs. Furthermore, NVG nano-composites exhibited reasonable wear characteristics at extreme temperatures. NV nano-composites showed better wear resistance at temperatures higher than 600 °C in the comparison to NVG nano composites. This behavior was attributed to the formation of an abrasive phase of carbides on the contact surface of NVG nano-composites at elevated temperatures.

Carbondots on V2O5 nanowires are a viable peroxidase mimic for colorimetric determination of hydrogen peroxide and glucose.

A nanocomposite was hydrothermally prepared from C-dots and V2O5 nanowires, and characterized by TEM, FTIR and XRD. Due to the synergistic effects between C-dots and V2O5 nanowires, the nanocomposite is found to possess peroxidase-mimicking activity. This finding was exploited to design colorimetric methods for determination of H2O2 and glucose (via glucose oxidase) by using of 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate. The C-dot/V2O5 nanocomposite catalyzes hydrogen peroxide to oxidize TMB and the resultant product, i.e., TMB* produces a blue color in the solution. Also for glucose determination, at first glucose reacts with dissolved oxygen in the presence of glucose oxidase and generates H2O2. Then, produced H2O2 was monitored by theC-dot/V2O5 nanozyme in the presence of TMB. Intensity of the blue color in the solution at wavelength of 650nm is an indication of H2O2 or glucose concentration. The response to H2O2 is linear in the 0.5-520μM concentration ranges, and that for glucose from 0.7μM to 300μM. Graphical abstract Schematic presentation of peroxidase mimicking activity of C-dot/V2O5 nanocomposite and its application as sensitive colorimetric H2O2/glucose assay by using of 3,3',5,5'-tetramethylbenzidine (TMB) as chromogenic substrate to induce a typical blue color reaction.

Enhancing oxygen evolution reaction electrocatalytic performance with vanadium-doped Co/CoO encapsulated in carbon nanorod

Oxygen evolution reaction (OER) plays a key role in electrochemical splitting of water and it is urgent to develop high-performance and cost-effective OER catalysts. In this work, we report the synthesis of V-Co/CoO@C nanorod as highly efficient OER catalysts. The V2O5 nanowire and metal organic framework composite leads to the successful preparation of the catalyst. The V2O5 nanowire not only induces the formation of Co/CoO species, but also facilitates uniform V doping. When used as OER catalyst, the V-Co/CoO@C nanorod only needs a low overpotential of 320 mV to achieve a high current density of 10 mA·cm−2.

In Operando Synchrotron Diffraction and in Operando X-ray Absorption Spectroscopy Investigations of Orthorhombic V2O5 Nanowires as Cathode Materials for Mg-Ion Batteries.

Orthorhombic V2O5 nanowires were successfully synthesized via a hydrothermal method. A cell-configuration system was built utilizing V2O5 as the cathode and 1 M Mg(ClO4)2 electrolyte within acetonitrile, together with Mg xMo6S8 ( x ≈ 2) as the anode to investigate the structural evolution and oxidation state and local structural changes of V2O5. The V2O5 nanowires deliver an initial discharge/charge capacity of 103 mAh g-1/110 mAh g-1 and the highest discharge capacity of 130 mAh g-1 in the sixth cycle at C/20 rate in the cell-configuration system. In operando synchrotron diffraction and in operando X-ray absorption spectroscopy together with ex situ Raman and X-ray photoelectron spectroscopy reveal the reversibility of magnesium insertion/extraction and provide information on the crystal structure evolution and changes of the oxidation states during cycling.

High-density sodium vanadate nanowires on substrate coated with polypyrrole for lithium-ion battery

A novel electrodeposited-hydrothermal method has been developed to fabricate high-density β-Na0.33V2O5 nanowire film on a metal current collector (Ti foil). The morphology, crystal structure, and the effects of deposition voltage, temperature and time on the prepared samples were tested and presented in detail. The thickness of the β-Na0.33V2O5 nanowire film was ∼10.5 μm under experimental conditions of 5 h time, 2.5 V voltage, and 90 °C temperature. When the β-Na0.33V2O5 nanowire film was coated with polypyrrole and served as a cathode of lithium-ion battery, it exhibited a high reversible discharge capacity of 269.9 mAh g−1 at a current density of 50 mA g−1. By contrast, the cycling behavior of this material is proved to be much better than the bare β-Na0.33V2O5 nanowire film. This research provides a new pathway to explore high tap density cathode materials for lithium-ion battery with enhanced electrochemical performance.

Construction of H2O2-responsive asymmetric 2D nanofluidic channels with graphene and peroxidase-mimetic V2O5 nanowires.

The flexible two-dimensional (2D) nanosheet structure, high specific surface, and unique electrical properties make graphene anemerging nano-building block for molecule-responsive nanochannels. Herein, we report a novel graphene and V2O5 nanowire-based porous asymmetric membrane, which shows excellent catalytic performance and sensitive and quick response for H2O2. Poly(diallyldimethylammonium chloride)-functionalized graphene nanosheets were made into restacked lamellar film with porous structure and high anion selectivity. V2O5 nanowire, a kind of enzyme-mimetic nanomaterial, was mounted on one side of the graphene membrane through a sequential vacuum filtration method. The V2O5 nanowires on the membrane have high catalytic activities for H2O2 reduction, with the Michealis-Menten constant (KM) of 1.74mM, better than various reported peroxidase-based nanocomposites and peroxidase mimics. This composite membrane showed quick response to H2O2 within 5s, with good reproducibility and high operational stability. The responsive linear range was from 10μM to 1mM, with the detection limit of 9.5μM. This fabrication of 2D layered nanomaterials and enzyme mimics could be extended for developing novel smart molecule-responsive devices. Graphical abstract ᅟ.

Freeze-drying method to synthesize V2O5/graphene composites toward enhanced sodium ion storage

V2O5 nanowires/Graphene composite was successfully constructed through a delicate method. SEM, TEM, XRD and Raman spectra were utilized to investigate the morphology and phase structure of as-obtained samples. When being compared with bare V2O5 nanowires, the as-obtained composite presented an enhanced performance of sodium ion storage. The results illustrated that the composite electrode can render a discharge specific capacity of 154 mA h g−1 during the first cycle, whereas it was 100 mA h g−1 for bare V2O5 nanowires electrode. It was worth noting that the method here to decorate graphene sheets with V2O5 nanowires was crucial to achieve the optimal electrochemical property. EIS and CV cures (at different scanning rate) indicated that the introduction of graphene sheets can enhance the electrical conductivity of as-obtained composite and facilitate the surface-controlled electrochemical reaction process of electrode. Finally, the enhanced sodium ion storage performance can be expected.

Electrochemical performance of silver vanadate/silver nanowire composite for lithium-ion batteries

Silver vanadate (Ag4V2O7) nanowires are synthesized through a simple and facile cation exchange method, and the silver vanadate/silver (Ag/Ag0.68V2O5) nanowires are obtained through calcination of Ag4V2O7 nanowires at 250-500 °C. By varying the reaction time, the progression of the cation exchange process is captured, and tunable morphologies, crystal structures and chemical components (Ag, V, Na and O) of the samples are achieved and analyzed using scanning electron microscope, transmission electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Also, as an electrode of lithium-ion battery, the Ag/Ag0.68V2O5 nanowires exhibit specific discharge capacities of 179.5 mAh g−1 in the first cycle and 152.6 mAh g−1 at the 150th cycle at a current density of 30 mA g−1. Good lithium-ion storage performance of the electrode mainly due its nanowire structure directly grown on titanium foil and good electron transportation caused by the high conductivity of the silver nanoparticles in the nanowires.

V2O5 nanowires-graphene composite as an outstanding electrode material for high electrochemical performance and long-cycle-life supercapacitor

A composite of V2O5 nanowires with reduced graphene oxide (V2O5-NW-G) has been prepared using facile hydrothermal method and tested for charge storage supercapacitor application. Morphological and structural aspects of as prepared materials has been studied using material characterization techniques like transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The nanosized wires like structure of V2O5 anchored on the graphene (rGO) sheets possesses improved electrical conductivity and high surface area. Electrochemical properties of the synthesized materials have been studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Composite (V2O5-NW-G) exhibits exceptional properties like high gravimetric capacitance of 1002 F g−1 along with good cyclic stability of 83.94% capacitance retention after 5000 repetitive GCD cycles. Excellent energy density of 116 Wh kg−1 has been obtained at the power density of 1520 W kg−1.

Interfacial Constructing Flexible V2O5@Polypyrrole Core-Shell Nanowire Membrane with Superior Supercapacitive Performance.

Flexible membrane consisting of ultralong V2O5@conducting polypyrrole (V2O5@PPy) core-shell nanowires is prepared by a facile in situ interfacial synthesis approach. The V2O5 is for the first time demonstrated to show versatile function of reactive template to initiate the uniform and conformal polymerization of PPy nanocoating without the need for extra oxidants. The freestanding PPy-encapsulated V2O5 nanowire membrane is of great benefit in achieving strong electrochemical harvest by increasing electrical conductivity, shortening ion/electron transport distance, and enlarging electrode/electrolyte contact area. When evaluated as binder- and additive-free supercapacitor electrodes, the V2O5@PPy core-shell hybrid delivers a significantly enhanced specific capacitance of 334 F g-1 along with superior rate capability and improved cycling stability. The present work would provide a simple yet powerful interfacial strategy for elaborate constructing V2O5/conducting polymers toward various energy-storage technologies.

Molecular Layer Deposition and Thermal Transformations of Titanium(Aluminum)-Vanadium Hybrid Organic-Inorganic Films

In this work Molecular layer deposition (MLD) technique used to synthesize titanium-vanadium (TiV x C y O z ) and aluminum-vanadium (AlV x C y O z ) hybrid organic-inorganic films via alternating surface reactions of titanium tetrachloride (or trimethylaluminum), vanadium oxochloride, and ethylene glycol. Using in situ monitoring it was found that the surface reactions were self-limiting at temperatures of 90 and 115°C. The coating thickness per molecular layer deposition cycle (growth rate) at 115°C on a silicon substrate varied from 5.8 to 11.4 A/cycle, and the film densities, from 1.7 to 2.0 g cm–3. An analysis of the samples obtained at 115°C revealed their amorphous structure. A thermal treatment of titanium-vanadium films at 450°C in air resulted in formation of highly structured coatings. These coatings were composed of nanowires of single-crystal vanadium oxide (V2O5) and mixed nanostructures of titanium and vanadium oxides. Increase in thermal treatment temperature to 500°C resulted in elongation of the V2O5 nanowires up to tens of micrometers and in their separation from the substrate. A thermal treatment of aluminum-vanadium films in air resulted in formation of a low-density film. Pyrolysis of the films in an inert gas yielded composite coatings containing domains of graphitized carbon. These films can be potentially useful in modern devices for energy storage, electronics, medicine and other promising fields of technology.

Cobalt-doped V2O5 nanowire arrays on Ti foil for enhanced lithium-ion storage

Cobalt (Co)-doped V2O5 nanowire arrays are prepared using a simple hydrothermal method by controlling appropriate molar ratios of cobaltous acetate (Co(CH3COO)2·4H2O) and ammonium vanadate (NH4VO3). The products are characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Fourier-transform infrared spectroscopy. The nanowires are identified as cobalt-doped V2O5 when the molar ratio of cobalt/vanadium precursors is less than 0.064 (calculated from raw materials); while as the molar ratio increases to 0.128, the nanowires are composed of a mixture of V2O5 and Co3O4. The valence states of Co, O and V are tested by X-ray photoelectron spectroscopy, and the distribution of these elements is confirmed by elemental mapping. The prepared samples are studied and compared with their lithium-storage properties using cyclic voltammetry, charge-discharge test and rate performances. The Co-doped V2O5 nanowires have a higher electrochemical lithium-storage capacity than that of the mixed V2O5/Co3O4 nanowires. At a current density of 30 mA g−1, an initial discharge capacity of 624.64 mAh g−1 is achieved in a voltage range of 2–4 V.

Designed Synthesis and Supercapacitor Electrode of V2O3@C Core‐shell Structured Nanorods with Excellent Pseudo‐capacitance in Na2SO4 Neutral Electrolyte

AbstractV2O3@C core‐shell structured nanorods (VCNR) were successfully prepared using V2O5 nanowires and glucose via a facile hydrothermal route combination of calcination. VCNR comprised of core‐shell structures with V2O3 cores and amorphous carbon shells. Electrochemical properties of VCNR as supercapacitor electrodes were studied in Na2SO4 neutral electrolyte. Results demonstrated that VCNR featured capacitive behavior originating from pseudocapacitance. Specific capacitances of VCNR at 0.5, 1, 2, 5 and 10 A⋅g−1 were achieved to 219, 192, 148, 127 and 119 F⋅g−1, respectively, and VCNR displayed higher specific capacitance than the values of carbon spheres and V2O3 particles. Maximum specific capacitance of VCNR reached 219 F⋅g−1 at 0.5 A⋅g−1 in present study, which was superior to the reported values of V2O3‐based materials and VO2‐based materials. Capacitance retention of VCNR was 100% after 700 cycles and 66% after 1000 cycles. Findings in present study proved that VCNR could be promising candidate as an ideal material for supercapacitors’ electrode.

Magnifying Opportunities in Mg Batteries through Metastability

In the March issue of Chem, Andrews, Banerjee, and colleagues devise a clever strategy to synthesize a metastable one-dimensional polymorph of V2O5 and demonstrate reversible chemical and electrochemical Mg intercalation, with 90 mAh/g capacity retained after 50 cycles at an average cell potential of 1.65 V versus Mg metal. Their approach proves fruitful not only in identifying a new functional multivalent cathode material, but also in validating a general concept that metastable compounds can offer sufficiently low migration energies to support reversible cycling with multivalent ions.

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.

Ceramic nanowelding

Ceramics possess high temperature resistance, extreme hardness, high chemical inertness and a lower density compared to metals, but there is currently no technology that can produce satisfactory joints in ceramic parts and preserve the excellent properties of the material. The lack of suitable joining techniques for ceramics is thus a major road block for their wider applications. Herein we report a technology to weld ceramic nanowires, with the mechanical strength of the weld stronger than that of the pristine nanowires. Using an advanced aberration-corrected environmental transmission electron microscope (ETEM) under a CO2 environment, we achieved ceramic nanowelding through the chemical reaction MgO + CO2 → MgCO3 by using porous MgO as the solder. We conducted not only nanowelding on MgO, CuO, and V2O5 nanowires and successfully tested them in tension, but also macroscopic welding on a ceramic material such as SiO2, indicating the application potential of this technology in bottom-up ceramic tools and devices.

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.

Hydrothermal encapsulation of VO2(A) nanorods in amorphous carbon by carbonization of glucose for energy storage devices.

In recent decades, tremendous attention has been paid to the development of new electrode materials with high capacitance to meet the requirements of electrode materials in supercapacitors. Among vanadium oxides, VO2(A) has recently received increasing attention due to its unique layered structure, phase transformation and applications in Li-ion batteries. However, few studies have focused on the electrochemical properties of VO2(A) as electrochemical capacitors. Herein, we develop a facile hydrothermal method to prepare VO2(A)@C core-shell structured composites by carbonization of glucose in the presence of V2O5 nanowires. The electrochemical properties of the VO2(A)@C core-shell composites are investigated as a supercapacitor electrode material for the first time; the composites show excellent pseudocapacitive behavior and display a specific capacitance as high as 179 F g-1 at 1 A g-1. A flexible asymmetric supercapacitor device is fabricated using VO2(A)@C composites and activated carbon and delivers an excellent capacitance of 0.5 F cm-2 at a scan rate of 5 mV s-1. Replacing the aqueous electrolyte with a LiCl/PVA gel electrolyte can efficiently improve the cycling performance to 85% retention after 1600 cycles. The good electrochemical performance of the composites indicates their high potential as electrode materials for supercapacitors.

Interwoven V2O5 nanowire/graphene nanoscroll hybrid assembled as efficient polysulfide-trapping-conversion interlayer for long-life lithium–sulfur batteries

An advanced lithium–sulfur battery interlayer configuration has been developed by engineering a lightweight, self-standing, and flexible hybrid film assembled from interwoven 1D V2O5 nanowires and graphene nanoscrolls.