This paper describes a procedure based on electrospinning for generating nanofibers of anatase with controllable diameters and porous structures. When an ethanol solution containing both poly(vinyl pyrrolidone) (PVP, Mw ≈ 1 300 000) and titanium tetraisopropoxide was injected through a needle under a strong electrical field, composite nanofibers made of PVP and amorphous TiO2 were formed (with lengths up to several centimeters) as a result of electrostatic jetting. These nanofibers could be subsequently converted into anatase without changing their morphology via calcination in air at 500 °C. The average diameter of these ceramic nanofibers could be controlled in the range from 20 to 200 nm by varying a number of parameters such as the ratio between PVP and titanium tetraisopropoxide, their concentrations in the alcohol solution, the strength of the electric field, and the feeding rate of the precursor solution. Both supported and free-standing mats consisting of anatase nanofibers have been successfully ...

Fabrication of Titania Nanofibers by Electrospinning

Metal oxides are the key ingredients for the development of many advanced functional materials and smart devices. Nanostructuring has emerged as one of the best tools to unlock their full potential. Tungsten oxides (WOx) are unique materials that have been rigorously studied for their chromism, photocatalysis, and sensing capabilities. However, they exhibit further important properties and functionalities that have received relatively little attention in the past. This Feature Article presents a general review of nanostructured WOx, their properties, methods of synthesis, and a description of how they can be used in unique ways for different applications. Tungsten oxides (WOx) are unique functional materials that can be obtained in a vast variety of nanostructured forms. This Feature Article presents a comprehensive review on the properties of WOx that goes beyond chromism and photocatalysis, for which they are usually investigated for. This is followed by a survey of their synthesis methods and implementations for different applications.

Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

This paper describes a vapor-phase approach to the facial synthesis of cupric oxide (CuO) nanowires supported on the surfaces of various copper substrates that include grids, foils, and wires. A typical procedure simply involved the thermal oxidation of these substrates in air and within the temperature range from 400 to 700 °C. Electron microscopic studies indicated that these nanowires had a controllable diameter in the range of 30−100 nm with lengths of up to 15 μm by varying the temperature and growth time. Electron diffraction and high-resolution TEM studies implied that each CuO nanowire was a bicrystal divided by a (111) twin plane in its middle along the longitudinal axis. A possible mechanism was also proposed to account for the growth of these CuO nanowires.

CuO Nanowires Can Be Synthesized by Heating Copper Substrates in Air

One dimensional nanostructured materials

In this paper, we describe how WO(3) hollow spheres have been synthesized in solution phase by the controlled hydrolysis of WCl(6) using novel carbon microspheres as the templates. All of the products were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized spheres had large diameters of about 400 nm and thin shells of about 30 nm composed of numerous small nanocrystals. Prompted by the porous structure and small crystal size of the shell wall, we constructed WO(3) hollow-sphere gas sensors and found that these sensors had good sensitivity to alcohol, acetone, CS(2), and other organic gases.

Highly Sensitive WO3 Hollow-Sphere Gas Sensors

A simple method was discovered to prepare tungsten oxide nanowires directly from tungsten metal. The structure and composition of the nanowires were characterized by high resolution tunneling electron microscopy (HRTEM) and energy dispersive X-ray scattering (EDX), respectively. The growth mechanism and potential applications of this material are discussed.

Siegmar Roth

Papers

Tungsten Oxide Nanowires on Tungsten Substrates