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Prussian white (PW), due to its low cost, easy synthesis, open structure, and fast ion extraction/interaction, is introduced to the electrochromic field. The PW films were successfully grown on indium tin oxide (ITO) glass by a facial hydrothermal method. Impressively, the PW film exhibits excellent electrochemical cycling stability without obvious decay over 10 000 cycles and a high coloration efficiency of 149.3 cm

Prussian whites (PWs) with a three-dimensional framework can accommodate the insertion and extraction of ions with large radius, which have been widely used in potassium ion batteries. However, PWs show the poor cycling performance and inferior rate ability because of high coordinated water. In this work, PWs with different water content were synthesized via a coprecipitation method by controlling the reaction temperature. The sample with low-coordination water prohibits the best electrochemical performance. It shows a high capacity of 120.5 mAh/g at 100 mA/g for potassium-ion batteries (KIBs). It also exhibits a good rate performance, displaying a capacity of 73.2 mAh/g at 500 mA/g.

The effects of fillers’ structure on microstructure, dielectric and thermal properties of the SiO2/PTFE composite were investigated. The composites were prepared by a calendering and hot-pressing process, and their dielectric, thermal properties of composites with various SiO2 fillers were studied. The morphologic analysis shows that open pores on the particles’ surface improve the interfacial adhesion between silica and PTFE without any chemical coupling agent. With the increase of the silica fillers content, the dielectric constants and dielectric losses of the composites increase gradually, while the thermal expansion coefficients decrease. The air phase in the porous fillers leads to low dielectric constants of the composites effectively. Bruggeman’s equation analysis indicates that solid-air interfaces influence the dielectric properties of the composites via the interfacial polarization. The difference between CTE testing results and theoretic prediction reveals that the microstructures, such as interfacial adhesion and particle size distribution, play the key roles in the thermal properties. It is suggested that the combination design of the microstructure and the component is a multi-scale strategy to tailor the properties of composites optionally for developing functional composites.

Sodium-ion batteries are regarded as the most promising alternative candidates for lithium-ion batteries. Hard carbon, as a kind of anode materials, has been demonstrated to deliver high specific capacity and stable cycling performance. However, it is still difficult to strike the balance between the relatively high cost and the superior electrochemical performance. We successfully fabricated low-cost lignite-derived hard carbons (a-LCs) with easy scale-up method. The microstructure, morphology and surface information of the obtained a-LCs are evaluated by X-ray diffraction, Raman spectrum and Fourier transform infrared spectrometer. By changing carbonization temperature, a-LCs’ microstructure and defect composition can be tuned and quite different sodium-ion storage behaviors can be seen. When carbonization temperature increases, the carbon microcrystallites grow and defects decay, resulting in a decrease in defect absorption capacity and an increase in graphitic-like nanodomain intercalation capacity. Particularly, a-LC carbonized at 1200 °C (a-LC-1200) can deliver a high capacity of 256 mAh g−1 with the initial Coulombic efficiency of 82%. Besides, it also exhibits a superior rate performance of 210, 197, 180, 168 and 146 mAh g−1 at current rates of 1, 2, 5, 10 and 20C (defined that 1C = 200 mA g−1), respectively. It solves the above problems very well and displays great commercial value.

With the development of capacitive deionization (CDI) technology, low-cost and high-performance capacitive deionization electrode materials have received great attention. Herein nanoporous carbon (NPC) was prepared using lignite as the carbon source in this work. The as-prepared NPC has a hierarchical nanoporous structure with micro-, meso- and macro-sized pores. Its specific surface area can reach 3581 m2 g−1. Then TiO2 nanoclusters modified NPC composites were fabricated for better CDI performance due to their synergistic electrochemical behaviour and properties. The results show that the size of TiO2 nanoclusters is 3–5 nm. TiO2 nanoclusters are uniformly dispersed in the composites which retain the hierarchical nanoporous structure and possess high specific surface area up to 3703 m2 g−1. Compared with NPC, the performance of xTiO2@NPC was significantly improved. The specific capacitance of 10TiO2@NPC is 193.45 F g−1 with 95% capacity retention after 5000 cycles. Its CDI adsorption capacity is up to 11.23 mg g−1, which is 1.55 times of NPC (7.24 mg g−1). It provides promising candidate materials for low-cost, industrial CDI applications with high performance through a facile method.

Problems associated with seeking the high-performance flexible cathode materials similar to graphene constitute one of the main obstacles to using lithium-ion batteries (LIBs) in next-generation flexible and wearable electronics. Herein, the bendable and self-standing electrodes based on Ag nanoparticles decorated on few-layers V2O5 nanosheets are successfully fabricated by simple liquid-phase exfoliation and sol-gel method. Exfoliated V2O5 nanosheets with few-layers achieve higher Li+ ions diffusion kinetics derived from faster Li+ transport along the b-axis in the layers. Besides, Ag-functionalized ultrathin V2O5 nanosheets, as a flexible electrode of LIBs, exhibit higher electronic conductivity, superior discharge capacity (301 mA h g−1 at 1 C) and better rate performance (128 mA h g−1 at 10 C). Benefiting from the homogeneous dispersion of Ag nanoparticles and excellent flexibility of V2O5 nanosheets, after 100 times of 180° bending, the capacity of Ag@V2O5 nanosheets can stabilize at 233 mA h g−1 after the 200th cycle.

The vanadium oxide/reduced graphene oxide (V2O5/rGO) composite catalyst which determined the selective catalytic reduction activity (SCR) of NO with NH3 was prepared by a simple solvothermal method. The physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, X-ray energy spectrometer (XPS) and N2 sorption isotherm measurement (BET). Results of NH3-SCR showed that the NO conversion of V2O5/rGO catalyst could reach 54.3% at 100 °C. And the removal of NO increased to 74.6% when the temperature was up to 220 °C. By characterizing the microstructure and morphology of the V2O5/rGO catalysts prepared by in-situ growth and mechanical mixing methods, it was further shown that V2O5 nanoparticles were highly dispersed and in situ growth on the rGO surface. Based on X-ray energy spectrometer, V2O5/rGO catalyst had good low temperature denitrification performance due to the chemical adsorption oxygen and low-valent vanadium oxide contained in V2O5/rGO catalyst, which was beneficial to the redox reaction between V2O5 and graphene.

Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication field. However, room temperature phase transformation of PTFE resins, which is accompanied by a large volume change (> 400 ppm/oC), seriously affects the dimensional stability and performance stability of materials. The LD125 modified glass fiber (GF) was introduced to the CaO-Li2O-Sm2O3-TiO2 (CLST)/PTFE composite, to reduce the thermal expansion coefficient (CTE) of the composites. The tri-phase composites (CLST/PTFE/GF) show the low dielectric loss and excellent machine-ability. The effect of GF content on the dielectric properties and CTE was also investigated. The CLST/PTFE filled with 5% GF exhibits the best overall performance, which is a promising microwave dielectric material for microwave communication.

MoO2 nanocrystals (NCs) on Ni foam were simply synthesized via a facile hydrothermal method and a dip-coating method. It was worth noting that ultrafine interconnected MoO2 nanocrystals (about 10 nm) were uniformly anchored on Ni foam to fabricate a particular three-dimensional architecture, which may provide more active sites and shorter transmission pathways for lithium ions. As binder-free anode, MoO2 NCs on Ni foam deliver a high initial discharge capacity of 990 mAh·g-1 and retain a reversible capacity of 924 mAh· g-1 after 100 cycles at a current density of 0.1 C. More importantly, when the current density returns from 2 C to 0.1 C, the capacity recovers to 910 mAh·g-1 (about 92% of the original high capacity), suggesting excellent cycling stability and rate capability. The particular 3D electrode as binder-free anode makes it a promising anode candidate for high-performance lithium-ion batteries.

PTFE-based ceramic-polymer dielectric composites have been widely researched in the communication field due to their good processing, wide range frequency and temperature stability and being able to provide tunable dielectric constant in a scale. In order to improve the compatibility between the ceramic fillers and polymer matrix without damage of dielectric properties, surface modifiers with less carbon remain are preferred. In this paper, tetraethylorthosilicate (TEOS) is employed as a surface modifier to improve the compatibility between the (Ca, Li, Sm)TiO3 (CLST) ceramic and PTFE, and the dispersion of the ceramic particles in the matrix. FTIR, XPS and TEM results indicate that TEOS is coated on the ceramic particles successfully and forms a silica coating layer. The surface modification improves the dispersion of particles in PTFE and interface contact between the ceramic fillers and PTFE matrix. These improve the thermal stability and reduce the dielectric loss of the dielectric composites. The CLST/PTFE composite modified by TEOS exhibits a dielectric constant of 6.22 with dielectric loss just 0.0012 at microwave frequencies (around 10 GHz).

The interpenetrated carbon nanosheets embedded with the MoO2 nanocrystallines (NCs) are self-assembling to a novel three-dimensional (3D) structure by a facile method. During the growth process, the MoO2 NCs induce the dopamine monomer to form polydopamine nanosheets, which construct the 3D framework and are further carbonized. It is worth noticing that MoO2 NCs with the size of 5 nm are uniformly loaded on the interpenetrated carbon nanosheets. More importantly, the design of this special 3D structure can contribute to enhancing the electrochemical performances owning to its large specific area and high electronic conductivity, which lead to not only higher capacity of 983 mA h g−1 after 200 cycles, but also better reversibility and rate capacities. These excellent electrochemical performances suggest that the unique 3D composite can act as a promising anode candidate for high-performance lithium-ion storage.

Carbon coated Na5V12O32 ultralong nanowires were synthesized by hydrothermal and solid-state reaction methods As a cathode material for sodium-ion batteries (SIBs), carbon coated Na5V12O32 ultralong nanowires exhibit high electrochemical performance with the redox potential ca. 2.8 V vs. Na+/Na, delivering initial discharge capacity of 105 mAh g−1 at a rate of C/50. Furthermore, Carbon coated Na5V12O32 ultralong nanowires have the tap density of 3.2 g cm−3 and volumetric energy density 940 Wh L−1. Results are confirmed that the carbon coating film with 10 nm thickness could effectively improve the electrochemical performance, and carbon coated Na5V12O32 ultralong may be used as cathode material for SIBs with highly environmental friendship and low cost.

Polytetrafluorethylene (PTFE) composites filled with perovskite (Ca,Li,Sm)TiO3 (CLST) dielectric ceramic of various volume fractions filler up to 60% were prepared. The effects of volume fraction of ceramic filler on the microstructure and dielectric properties of the composites have been investigated. A comparative study of dielectric properties of experiment and modeling analysis has been carried out at high frequencies for the CLST/PTFE composites. The results indicate that both the dielectric constant and the dielectric loss increase with the filler. The CLST/PTFE composite with 40% ceramic has exhibited good dielectric properties: e r = 7.92 (~10 GHz), tan δ = 1.2 × 10−3 (~10 GHz), and τ f = −45 ppm/°C. The dielectric properties are obviously better than most composites reported previously at high frequencies in the aspects of dielectric loss and thermal stability. The dielectric constant and dielectric loss of composites predicted by the Rother–Lichtenecker equation and the general mixing model are in good agreement with the experiment data when the volume fraction of ceramic is less than 40%. When the volume fraction of the ceramic is more than 40%, the deviation occurs. By introducing the correction factor, the theoretical values of the dielectric constant agrees well with the experimental values.

MoO2 nanoparticles (NPs) and reduced graphene oxide (rGO) nanocomposites (MoO2 NPs/rGO) with different rGO contents were prepared by a two-step hydrothermal process. When the content of rGO was 10 wt%, the MoO2 nanoparticles were uniformly deposited on the rGO nanosheets, and the corresponding MoO2 NPs/rGO nanocomposites also exhibited the highest reversible capacities of 1647 mAh g−1 at the first cycle and 1269 mAh g−1 after 100 cycles. This material also had stable rate capacity for 991 mAh g−1 at 1 mA cm−2. The outstanding electrochemical performance of the nanocomposite may be attributed to the synergistic interaction between MoO2 NPs and rGO, as there were enough void spaces to buffer volume change in the microstructures of the MoO2 NPs/rGO nanocomposites. Furthermore, rGO nanosheets in the MoO2 NPs/rGO nanocomposites could act as not only active materials but also electronic conductive channels to improve the electrochemical performance.

s Flexible electrochromic (EC) display devices have received extensive attention due to their application in the new generation of smart and wearable devices. 2D ultrathin nanosheets are the promising structure to allow EC materials (such as V2O5, WO3) to be incorporated into flexible EC electronics owing to their surface-to-surface contact with the flexible substrate. Herein, the graphene-like V2O5 nanosheets (V2O5 NSs) with thicknesses ranging from few-layers (4 nm) to 40 nm are synthesized by liquid-phase exfoliation (LPE) method. To enhance the electronic conductivity and decrease the agglomeration of V2O5 NSs, graphene oxide (GO) is introduced to fabricate V2O5 NSs/GO films by layer-by-layer (LBL) assembly method. The composite films exhibit ultrafast coloring responsion time (1.6 s) and bleaching time (2 s) attributed to the reduced charge transport distances of 2D ultrathin structure. The LBL assembly structure accompanied by larger Li+ ions storage surface areas facilitates the superior transmittance contrast (ΔT) of 57.5% at 425 nm and reversible yellow/green/blue-grey color changes. Besides, the flexible V2O5 NSs/GO films on ITO/PET substrate still display rapid responsion speed (2.7 s/4.3 s) after bending 100 cycles with the bending angle of 90°, which manifests their potentially application for flexible EC devices.

Energy storage plays an important role in modern society. However, the cost limits its large-scale application. We design a low-cost carbon material as anode for the low-cost system of potassium-ion batteries. The batteries assembled with the obtained carbon as anode exhibit brilliant electrochemical performance, including encouraging capacities and good cycling stability. This work provides a promising strategy for large-scale energy storage applications.

In this paper, Ba(Mg1/3Ta2/3)O3 (BMT) thin films were prepared by an aqueous solution–gel method on the Pt/Ti/SiO2/Si(1 0 0) substrates with different annealing temperatures. The residual stress in the BMT thin films was investigated by nanoindentation technique. As the annealing temperature increases from 700 °C to 800 °C, the residual stress by nanoindentation technique in the BMT thin film increases from 418 MPa to 475.9 MPa, which is consistent with theoretical value ranged from 402.5 MPa to 486.2 MPa. Therefore, nanoindentation technique is an effective tool for detection of the residual stress in BMT thin films. Effect of residual stress on the dielectric properties of BMT thin films annealed at different temperatures was also studied. The increase in dielectric constant of BMT thin films annealed at 700 °C and 750 °C is larger than that of BMT thin films annealed at 750 °C and 800 °C due to the combined effect of the grain size and residual stress.

Sn 4+ doped Ba(Mg 1/3 Nb 2/3 )O 3 (BMN) transparent ceramics were synthesized by a solid state reaction. Sn 4+ doping changes the crystal structure from hexagonal symmetry to cubic symmetry without birefringence and improves the microstructure. The tilting of oxygen octahedra caused by Sn 4+ doping influences the A–O and B–O bond characters. The optical transmittance of the transparent ceramic sintered at 1550 °C for 48 h in oxygen atmosphere was 53%. A high refractive index of 2.09–2.22 was achieved in the wavelength range of 400 to 1000 nm. Effective ultraviolet absorption was also obtained when the cut-on wavelength shifted to the edge of the visible region. The optical properties meet the miniaturization requirement for optical functional elements.

In the present research, the Ba(Mg1/3Nb2/3)O3 (BMN) thin films with high 1:2 long-range order (LRO) were prepared by an entire aqueous solution–gel route and a heat treatment at low temperature. The BMN precursor solutions used for spin-coating consist of tri-metal ions citrate complexes, which are formed through the combination of three single citrate complexes with NH4+ acting as crosslinks. The metal-coordinated bonds of the citrate complexes can be easily broken by heat treatment, which can result in the crystallization of BMN films at low annealing temperature. The crystalline structure and LRO degree of BMN films were also investigated. It is shown that the LRO degrees increase with the increase in annealing temperature. The dielectric constant increases and the dielectric loss decreases with the annealing temperature up to 750°C due to the improvement of the film densification and the LRO degree. The further increase in annealing temperature slightly decreases the dielectric constant and increases the dielectric loss due to the appearance of large aggregates. It is shown that the charge carriers mainly contribute to the dielectric response below 100 KHz, while the dipolar response starts to take effect for the frequency higher than 100 KHz.

A facile and green hydrothermal method has been developed to fabricate three-dimensional nanoarchitecture composites consisting of MoO2 nanoparticles decorated on the graphene oxide (GO). The composites were characterized by XRD, SEM, and HRTEM. It was demonstrated that MoO2 nanoparticles are 5–15 nm in size and homogeneously dispersed on GO and denoted as MoO2-GO composites. When tested as an anode material for lithium-ion batteries, the MoO2-GO composites exhibited an improved storage capacity and cycling performance, higher than the pure MoO2 nanoparticles. As a result, the GO effectively forms a conductive network that greatly enhances the electrical conductivity and structural stability of composites. The incorporation of the flexible and conductive GO and the small homogeneous MoO2 nanoparticles could not only maintain the structural and electrical integrity, but also accommodate the volume change during the lithium-ion intercalation and de-intercalation. The ultrafine MoO2 nanoparticles dispersed o...

A simple and low-cost method involving pencil-drawing and electrodeposition is introduced to fabricate graphite/polyaniline hybrid electrodes on paper for flexible solid-state supercapacitors. The as-prepared hybrid electrodes, which are chemically stable, show a low sheet resistance of 32.3 Ω sq −1 and a high areal capacitance of 355.6 mF cm −2 at a current density of 0.5 mA cm −2 . The paper-based symmetric supercapacitors assembled by two pencil-drawing graphite/polyaniline networks hybrid electrodes exhibit a volume capacitance of 3.55 F cm −3 at a current density of 4.57 mA cm −3 , and an energy density of about 0.32 mWh cm −3 at a power density of 0.054 W cm −3 normalized to the whole volume of the solid-state device. These encouraging results show their great potential in flexible and solid-state energy storage systems.

Hydrated vanadium pentoxide (V2O5·nH2O) nanorod arrays with diameters of ∼200 nm and lengths of more than 5 μm have been synthesized via template-based physical wetting of V2O5 sols. The V2O5·nH2O ...

Recently, nanostructured materials have attracted great interest in the field of lithium-ion batteries, essentially because of their substantial advantages, such as short transport path lengths for both electrons and Li ions, a large amount of contact surface area between the electrode and electrolyte, and large flexibility and toughness for accommodating strain introduced by Li insertion/extraction. Among the transition-metal oxides, nanostructured MoO3 has been extensively investigated as a key material for fundamental research and technological applications in optical devices, smart windows, catalysts, sensors, lubricants, and electrochemical storage. There are two basic polytypes of MoO3: orthorhombic MoO3 (a-type) being a thermodynamically stable phase, and the metastable monoclinic MoO3 (b-type) with a ReO3-type structure. The most important structural characteristic of a-MoO3 is its structural anisotropy, which can be considered as a layered structure parallel to (010) (See the inset of Fig. S1, Supporting Information). Each layer is composed of two sub-layers, each of which is formed by corner-sharing octahedra along [001] and [100]; the two sub-layers stack together by sharing the edges of the octahedra along [001]. An alternate stack of these layered sheets along [010] would lead to the formation of a-MoO3, where a van der Waals interaction would be the major binding force between the piled sheets. One might take advantage of the intrinsic structural anisotropy of a-MoO3 for tuning its properties by interlayer structural modification, annealing, and lithiation. In this Communication, we report the electroactivity of a-MoO3 nanobelts after lithiation that show superior performance to nonlithiated a-MoO3 nanobelts. An X-ray diffraction (XRD) measurement was performed using a D/MAX-III X-ray diffractometer. Fourier-transformed infrared (FTIR) absorption spectra were recorded using the 60-SXB IR spectrometer. Raman spectra were taken using a Renishaw RM-1000 laser Raman microscopy system. Scanning electron microscopy (SEM) images were collected with a JSM-5610 and FES-EM LEO 1530. Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) were recorded by using a JEOL JEM2010 FEF microscope. The electrochemical properties were studied with a multichannel battery testing system. Batteries were fabricated using a lithium pellet as the negative electrode; 1 M solution of LiPF6 in ethylene carbon (EC)/dimethyl carbonate (DMC) as the electrolyte; and a pellet made of the nanobelts, acetylene black and PTFE in a 10:7:1 ratio as the positive electrode. The fabrication of a single nanobelt-based device has been described in detail elsewhere. XRD measurement was first used to study the phase and lattice modification of the nanobelts before and after lithiation (Fig. 1A). The diffraction peaks of the XRD pattern for both samples can be readily indexed to be orthorhombic with lattice constants of a = 3.962 A, b = 13.85 A, c = 3.697 A (International Centre for Diffraction Data (ICDD) No. 050508). No peaks of any other phases were detected, indicating the high purity of the MoO3 nanobelts. For the non-lithiated MoO3 nanobelts, the stronger intensities of (020), (040), and (060) peaks than those for the bulk MoO3 (Fig. S1, Supporting Information) indicates the anisotropic growth of the nanostructure as well as the preferred orientation of the nanobelts on the substrate. Importantly, in comparison to the nonlithiated sample, there is a small shift of the (020) peak toward a lower diffraction angle for the lithiated sample. This is direct evidence of an expanded b-plane interlayer distance for 0.065 A after lithiation, possibly due to the introduction of Li interstitials between the layers. The morphology and microstructure of the products were observed by using SEM and TEM. Before lithiation (Fig. 1B), C O M M U N IC A TI O N

Hydrated vanadium pentoxide (V2O5·nH2O) nanotube arrays with outer diameters of 200 nm and lengths of more than 5 μm have been synthesized via template-based physical wetting of V2O5 sols. The V2O5·nH2O nanotube arrays were characterized by scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy . The field emission (FE) of the V2O5·nH2O nanotube arrays shows a turn-on field of about 6.35 V/μm at a current density of 10 μA/cm2 and an emission current density up to 2.1 mA/cm2 at a field of 9.20 V/μm. The corresponding Fowler−Nordheim plot shows a linear behavior. These features make the V2O5·nH2O nanotube array a promising candidate for FE emitters.

One-dimensional vanadium and molybdenum oxide nanomaterials have been synthesized using a rheological reaction followed by a self-assembling process. The replacement of V in VONTs by Mo with a larger ionic radius results in a shorten diffusion length of Li + ions and an improved electrochemical performance. The special composites composed of nano-scale Ag and organic template molecular exist in the hollow nanotubes and between the VO x layers of nanotube wall resulting in the change of the interlayer distance of nanotube wall and nanotube diameters, and thereby, improved electrochemical performance. The VO 2 ( B ) nanorods were treated by H 2 O 2 and CTAB solution and VO 2 ( M ) nanorods were attained through phase transfer process of VO 2 ( B )→VO 2 ( R )→VO 2 ( M ). The observed MoO 3 nanorods with the average width of 100 nm consist of several thin layers contacting each other. The electrochemical property of this special structure is proved to be good.

Novel vanadium dioxide nanorods were fabricated via a surfactant-assisted hydrothermal method at 180 °C for 48 h in the presence of cetyltrimethylammonium bromide (CTAB). The self-assembled samples were characterized by XRD, SEM, TEM, HRTEM and FT-IR. The results show that the products are nanorods, which are pure B phase vanadium dioxide with high crystallinity. The obtained nanorods have diameters of 40–60 nm with lengths up to 1–2 um. The probable formation mechanism of vanadium dioxide is also discussed.

MoO2 nanorods were synthesized by hydrothermal method using ethyl alcohol as reducing agent. The pristine MoO2 exhibited a reversible discharge capacity of 300 mAh·g−1 under the current density of 0.1 mA·cm−2. PANI/MoO2 nanocomposites were obtained and the electrochemical tests demonstrated that the hybrid exhibited enhanced discharge capacity of 530 mAh·g−1 as an anode material for lithium-ion batteries.

Monoclinic NH4V3O8 single-crystalline nanobelts with widths of 80−180 nm, thicknesses of 50−100 nm, and lengths up to tens of micrometers have been synthesized at large scale in an ammonium metavanadate solution by a templates/catalysts-free route. Such nanobelts grow along the direction of [010]. The individual NH4V3O8 nanobelt exhibits nonlinear, symmetric current/voltage (I/V) characteristics, with a conductivity of 0.1−1 S/cm at room temperature and a dielectric constant of ∼130. The dominant conduction mechanism is based on small polaron hopping due to ohmic mechanism at low electric field below 249 V/cm due to Schottky emission at medium electric field between 249 and 600 V/cm and due to the Poole−Frenkel emission mechanism at high field above 600 V/cm.

Monoclinic NH(4)V(3)O(8) single-crystalline nanobelts with widths of 80-180 nm, thicknesses of 50-100 nm, and lengths up to tens of micrometers have been synthesized at large scale in an ammonium metavanadate solution by a templates/catalysts-free route. Such nanobelts grow along the direction of [010]. The individual NH(4)V(3)O(8) nanobelt exhibits nonlinear, symmetric current/voltage (I/V) characteristics, with a conductivity of 0.1-1 S/cm at room temperature and a dielectric constant of approximately 130. The dominant conduction mechanism is based on small polaron hopping due to ohmic mechanism at low electric field below 249 V/cm due to Schottky emission at medium electric field between 249 and 600 V/cm and due to the Poole-Frenkel emission mechanism at high field above 600 V/cm.

VO2 (M) nanorods have been synthesized and the morphology and structure of the sample were characterized by XRD, SEM, and HRTEM. The results show that for VO2 (M) nanorods, the transition temperature is 65 °C and the hysteresis loop width is 8 °C. The active energy of low temperature semiconducting phase is 0.2eV, which indicates that its Fermi energy level situates on the middle energy level of the forbidden-band. The doping of Mo6+ decreases its transition temperature.

Vanadium oxide nanotube dispersions were investigated in water suspensions and characterized by TEM, absorption spectroscopy and optical limiting testing. The results show that the nanotubes are unrolled and oxidized after 6-day aging, resulting in some change of optical limiting property at the two wavelengths (532 and 1064 nm). The 1.27-eV absorption band is assigned as a superposition of both V d→d and V4+→V5+ charge-transfer excitations, and the features at 2.9 eV are attributed to O 2p→V 3d charge-transfer excitations.

Novel vanadium dioxide nanorods in diameter of 40–60 nm and in length up to 1–2 μm were successfully fabricated via a surfactant-assisted hydrothermal method at 180 °C for 48 h. Electrochemical tes...