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Tungsten oxide has drawn widespread attention due to its outstanding physical properties; however, the use of high temperature, low pressure, and expensive catalysts has been challenging in the synthesis of tungsten oxide nanowires. In this study, we developed a single step thermal evaporation process without any catalyst to synthesize WO3−x nanowires on silicon substrates and indium tin oxide glass substrate safely and economically. We utilized the Taguchi method to design experiments for the synthesis of tungsten oxide nanowires and analyze the effect of processing parameters. The growth mechanism of nanowires is proposed to be a vapor–solid mechanism. Confirmed to be oxygen-vacancy-rich WO3−x nanowires through high-resolution transmission electron microscopy studies, the nanowires have a great morphology with a high aspect ratio of around 700. The electrical resistivity of a single WO3−x nanowire at 300 K was measured to be 2.32 × 10−5 Ω M, which is relatively low due to rich oxygen vacancies. We synthesized WO3−x nanowires on an indium tin oxide glass substrate and assembled electrochromic devices with LiClO4/PC as the electrolyte. The devices were demonstrated to have fast coloring and bleaching rates of less than one second at low voltage; at high voltage, the color of the devices could change to a deeper color but take more than 2 seconds to react. Compared with previous works, the electrochromic devices from this study exhibit superior response time and stability. These significant results make WO3−x nanowires promising materials for applications in semiconductors, nanodevices, display and green technology. [ABSTRACT FROM AUTHOR]

In this study, indium tin oxide nanowires (ITO NWs) with high density and crystallinity were synthesized by chemical vapor deposition (CVD) via a vapor–liquid–solid (VLS) route; the NWs were decorated with 1 at% and 3 at% silver nanoparticles on the surface by a unique electrochemical method. The ITO NWs possessed great morphologies with lengths of 5~10 μm and an average diameter of 58.1 nm. Characterization was conducted through transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) to identify the structure and composition of the ITO NWs. The room temperature photoluminescence (PL) studies show that the ITO NWs were of visible light-emitting properties, and there were a large number of oxygen vacancies on the surface. The successful modification of Ag was confirmed by TEM, XRD and XPS. PL analysis reveals that there was an extra Ag signal at around 1.895 eV, indicating the potential application of Ag-ITO NWs as nanoscale optical materials. Electrical measurements show that more Ag nanoparticles on the surface of ITO NWs contributed to higher resistivity, demonstrating the change in the electron transmission channel of the Ag-ITO NWs. ITO NWs and Ag-ITO NWs are expected to enhance the performance of electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]