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Zn anode-based electrochromic devices (ZECDs) stand out as a highly promising technology in the upcoming era of multifunctional electronic devices, offering a blend of electrochromic capabilities and energy storage functions within a single transparent platform. However, significant challenges persist in achieving efficient patterning, ensuring long-term stability, and fast color-switching kinetics for these devices. In this study, heterogeneous tungsten oxide nanowires (W17O47/Na0.1WO3, WNOs) are formulated into inkjet printing ink to assemble patternable ZECDs. The heterogeneous electrode structure of WNO enables a highly capacitive-controlled mechanism that promotes fast electrochromic/electrochemical behavior. Notably, by utilizing a three-dimensional MXene mesh modified substrate, the inkjet-printed ZECDs exhibit a wide optical modulation range of 69.13%, rapid color-changing kinetics (tc = 4.1 s, tb = 5.4 s), and highly reversible capacities of 70 mAh cm-2 over 1000 cycles. This scalable strategy develops the patterned electrodes with a wide optical modulation range and substantial energy storage properties, offering promising prospects for their application in next-generation smart electronics. [ABSTRACT FROM AUTHOR]

Pt is the cause of the high total cost of fuel cells and electrolyzers, leading to difficult commercialization. Here, various types of metal atoms, i.e., Pt, Pd, Ni, Ir, Ag, and Rh, suitable for catalysts are used and supported by W18O49 nanowires for oxygen evolution reaction (OER) by the density functional theory (DFT) method. Four adsorbate molecules involved in OER were tested on adsorption energy: OH, O, OOH, and OO. Although the adsorption energy of these adsorbate molecules indicates that W18O49 has low adsorption energy, the Gibbs free energy diagram demonstrates that W18O49 has high OER reaction energy. Pt, Pd, Ni, and Rh have the lowest Gibbs energy to initiate the reaction and reasonable Gibbs free energy for other OER reactions. Bimetallic or trimetallic active sites can be developed along with selecting other metals with Pt, Pd, Rh, and Ni to reduce the Gibbs free energy difference for the decomposition of OH to O and OOH to H2O. Ag metal can also be applied as a second or third metal because Ag exhibits a relatively low Gibbs free energy difference in the O to OOH step. A selectivity study of each step on bimetallic and trimetallic active sites needs to be performed. [ABSTRACT FROM AUTHOR]

Tungsten oxide (W18O49) nanowires exhibit a unique near-infrared optical response due to their oxygen defects, which is important for both basic research and device applications. The diameter of W18O49 nanowires strongly affects the performance of their thin films, and samples with smaller diameters are required for improvement of such device performances by taking an advantage of larger surface area. However, in the conventional synthesis process, aggregation of nanowires and bundle formation inhibit the preparation of nanowires with small diameters. In this study, we prepared W18O49 nanowire samples with relatively small diameters through the control of the aggregation using a dispersant such as poly(ethylene glycol) (PEG), and evaluated their structures and optical properties. We found that PEG treatment can effectively reduce the diameter of the bundles, and W18O49 nanowire samples mainly containing relatively small bundles with an average diameter of less than 10 nm were obtained. [ABSTRACT FROM AUTHOR]

Herein, the growth of substoichiometric tungsten oxide (WO3–x) nanowires (NWs) via thermal oxidation of W films (a few 10 to a few 100 nm thick) deposited by Ar‐plasma sputtering on fluorine‐doped tin oxide (FTO) substrates is reported. A thermal treatment at relatively low temperature (525–550 °C) in Ar at atmospheric pressure leads to the conversion of the W films into W suboxide (WO3–x) NW arrays. Such NWs have a length of ≈500 nm and their diameter ranges from 10 to 40 nm depending on the duration of the annealing process. These growth conditions for the formation of WO3–x NWs are significantly milder and more straightforward than those reported in previous literature. This avoids high temperatures (e.g., above 600 °C), vacuum conditions, or the addition of catalysts. A thermal‐oxidative approach of these sputtered films is suitable to directly form WO3–x NWs on various surfaces, including conductive substrates to fabricate photoelectrodes or large‐scale supports, e.g., for smart windows. [ABSTRACT FROM AUTHOR]

Significance: We developed a facile approach for fast growth of branched nanotrees in a newly designed double‐wire‐feeder incorporated flame vapor deposition system. Nuclei formation on preformed nanowires for branch growth is innovatively done by traversing horizontal wire across flame. The density of nanobranches and resultant morphology of branched nanotrees could be tuned through a precise control over wires‐feeding pattern. The entire process can be done coherently without necessity of other process involvement or any interruption. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1138–1143, 2019 [ABSTRACT FROM AUTHOR]

Ammonia detection at low temperatures below 150 °C is attractive to be well suited for flexible substrates in terms of thermal strain and to specific environment not allowing high temperature such as explosive one. In commercial gas sensors, tungsten trioxide is the mostly used semiconducting metal oxide after tin dioxide. We report herein the efficiency of tungsten trioxide nanowires deposited on rigid substrate by drop coating from colloidal solution. This study provides an interesting approach to fabricate ammonia sensors on conformable substrate with significant properties for applications in environmental monitoring devices.

Tungsten oxide is an intensively studied semiconductor with the relevant application as H 2 S gas sensor. In this work we report on H 2 S gas sensor devices based on tungsten oxide nanowire networks, which are integrated on a CMOS fabricated microhotplate chip. Tungsten oxide gas sensors were prepared by the deposition of nanowire networks onto interdigitated electrodes on CMOS. The material properties of the tungsten oxide nanowires were investigated by TEM and Raman spectroscopy, confirming their non-stoichiometric state. Utilising WO 3-x nanowire networks as gas sensing material we obtained extraordinary sensitivity to H 2 S: concentrations down to 10 ppb have been detected, even in the presence of 50% relative humidity. [ABSTRACT FROM AUTHOR]

In the present work, the tungsten oxide (WO 3 ) nanowires functionalized silicon nanowires (SiNWs) with cactus-like structure has been successfully synthesized for room-temperature NO 2 detection. The novel nanocomposite was fabricated by metal-assisted chemical etching (MACE) and thermal annealing of tungsten film. The WO 3 nanowires were evenly distributed from the upper to the lower part of the SiNWs, indicating excellent uniformity which is conducive to adsorption and desorption of gas molecules. The gas-sensing properties have been examined by measuring the resistance change towards 0.25–5 ppm NO 2 gas. At room temperature, which is the optimum working temperature, the SiNWs/WO 3 nanowires composite showed two-times higher NO 2 response than that of the bare SiNWs at 2 ppm NO 2 . On the contrary, the responses of composite sensors to high concentrations of other reducing gases were very low, indicating excellent selectivity. Simultaneously, the composite sensors exhibited good sensing repeatability and stability. The enhancement in gas sensing properties may be attributed to the change in width of the space charge region, which is similar to the behavior of p-n junctions under forward bias, in the high-density p-n heterojunction structure formed between SiNWs and WO 3 nanowires. [ABSTRACT FROM AUTHOR]

An in-depth mechanistic understanding of the electrochemical lithiation process of tungsten oxide (WO3) is both of fundamental interest and relevant for potential applications. One of the most important features of WO3 lithiation is the formation of the chemically flexible, nonstoichiometric LixWO3, known as tungsten bronze. Herein, we achieved the real-time observation of the deep electrochemical lithiation process of single-crystal WO3 nanowires by constructing in situ transmission electron microscopy (TEM) electrochemical cells. As revealed by nanoscale imaging, diffraction, and spectroscopy, it is shown that the rapid and deep lithiation of WO3 nanowires leads to the formation of highly disordered and near-amorphous LixWO3 phases, but with no detectable traces of elemental W and segregated Li2O phase formation. These results highlight the remarkable chemical and structural flexibility of the LixWO3 phases in accommodating the rapid and deep lithiation reaction. [ABSTRACT FROM AUTHOR]

Preparation of size-tunable ultrathin W18O49 nanowires by an alcohol-assisted solvothermal decomposition of tungstic acid is reported. The synthesis of ultrathin W18O49 nanowires can be achieved at large scale and low cost, while changing the molecular size of the used alcohols can control the nanowire morphology. With increasing the molecular size of the alcohol, the synthesized W18O49 nanowires have smaller diameters and longer lengths. The as-prepared blue W18O49 nanomaterials show a very strong visible light absorption caused by oxygen defects and an aspect ratio-dependent photocatalytic activity on the degradation of pollutant rhodamine B (RhB) under simulated solar light irradiation. It is found that the W18O49 nanowires with highest aspect ratio show the highest activity in the photodegradation of RhB, which could be related to their higher density of oxygen surface defects in combination with a higher adsorption capability of RhB. This new synthetic route of size tunable ultrathin W18O49 nanomaterials will enlarge their potential applications and can be possibly used in the pyrolyzing synthesis of other metal oxide nanomaterials. [ABSTRACT FROM AUTHOR]

Abstract: Quasi-orienting W18O49 nanowire bundles were synthesized by solvothermal method. The microstructures and the NO2-sensing properties of the as-synthesized nanowires annealed at different temperatures were studied. To characterize the morphology and crystalline structure of the annealed tungsten oxide, field emission scanning electron microscope, X-ray diffraction and transmission electron microscope were employed. It was found that with annealing temperature increasing, the nanowire bundles became straighter and slightly thicker, and eventually a nonobelt-like structure was formed via the nanowires coalescence at 450°C. Meanwhile, the monoclinic W18O49 was transformed to monoclinic WO3 when annealing temperature rising from 350 to 450°C. In comparison to the W18O49 nanowire bundles-based sensor, the sensor based on the 450°C annealing-induced WO3 nanobelt-like structure exhibited markedly higher response value and gas selectivity, as well as much better response-recovery characteristics to NO2 gas due to its favorable microstructure feature to gas-sensing. [Copyright &y& Elsevier]

Abstract: In this work, electrical transport properties of discrete tungsten oxide nanowires and changes in their electrical properties in response to irradiation of laser beam were investigated. The tungsten oxide nanowires were found to exhibit photo-sensing property and the photo-induced modification in their electrical conductivity was found to be highly wavelength selective. Experiments carried out in controlled environment suggest that the observed wavelength selective photoresponse in these nanowires was due to laser-induced desorption of water and oxygen molecules from the nanowires which in turn resulted in a change in electrical conductivity of the nanowires. [ABSTRACT FROM AUTHOR]

Abstract: Tungsten oxide (WO3) nanowires with diameters of 15–40nm and lengths of hundreds of nanometers were synthesized by thermal chemical vapor deposition (CVD) without using any catalyst in a low-temperature zone (200–300°C) of a tube furnace via a two-step heating process. The morphology, composition, and crystal structure were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), Raman, ultraviolet UV–visible, and cathodoluminescence (CL) spectroscopy. XRD and TEM confirmed that the nanowires were triclinic WO3 with growth direction along [001]. Blue emission was observed in both the UV–visible and CL spectrum, indicating that the WO3 nanowires exhibited a red-shift at an optical absorption wavelength due to oxygen deficiencies. The crystallinity and size distribution of the nanowires influenced the bandgap. In the CL spectrum, the blue emission was at shorter wavelengths than reported previously, which can be attributed to the nanoscale size effect. [ABSTRACT FROM AUTHOR]

Abstract: Bundled tungsten oxide nanowires with controllable morphology were synthesized by a simple solvothermal method with tungsten hexachloride (WCl6) as precursor and cyclohexanol as solvent. The as-synthesized products were systematically characterized by using scanning electron microscopy, X-ray diffraction and transition electron microscopy. Brunauer–Emmett–Teller gas-sorption measurements were also employed. Accompanied by an apparent drop of specific surface area from 151 m2 g−1 for the longer nanowires synthesized using a lower concentration of WCl6 to 106 m2 g−1 for the shorter nanowires synthesized using a higher concentration of WCl6, a dramatically morphological evolution was also observed. With increasing concentration of tungsten hexachloride (WCl6) in cyclohexanol, the nanostructured bundles became larger, shorter and straighter, and finally a block-shape product occurred. [Copyright &y& Elsevier]

Abstract: We investigated the effect of the degree of dispersion of tungsten oxide nanowires on their field emission properties. We patterned tungsten films with 1×1μm2 islands of various pitches (2, 5, 10, 20 and 30μm) by electron beam lithography, sputtering and the lift-off technique, and then synthesized tungsten oxide nanowires on the islands. The number of nanowires per island was about 100. The sample with islands of 5μm pitch exhibited the highest field emission current. We performed electrostatic simulations of an electric field around emitters (1μm length) placed at various intervals. The simulation results had the same features as the experimental results. [Copyright &y& Elsevier]

The article focuses on the observation of intact laser desorption ionization (LDI) of peptide molecules from the arrays of tungsten oxide (WO3) nanowires through laser irradiation. Topics discussed include the use of metal oxide nanowires for the possible enhancement of LDI, fabrication process, and mechanism of LDI on the surface nanostructures.