Bundled tungsten oxide nanowires under thermal processing

Abstract

Ultra-thin W(18)O(49) nanowires were initially obtained by a simple solvothermal method using tungsten chloride and cyclohexanol as precursors. Thermal processing of the resulting bundled nanowires has been carried out in air in a tube furnace. The morphology and phase transformation behavior of the as-synthesized nanowires as a function of annealing temperature have been characterized by x-ray diffraction and electron microscopy. The nanostructured bundles underwent a series of morphological evolution with increased annealing temperature, becoming straighter, larger in diameter, and smaller in aspect ratio, eventually becoming irregular particles with size up to 5 µm. At 500 °C, the monoclinic W(18)O(49) was completely transformed to monoclinic WO(3) phase, which remains stable at high processing temperature. After thermal processing at 400 °C and 450 °C, the specific surface areas of the resulting nanowires dropped to 110 m(2) g(-1) and 66 m(2) g(-1) respectively, compared with that of 151 m(2) g(-1) for the as-prepared sample. This study may shed light on the understanding of the geometrical and structural evolution occurring in nanowires whose working environment may involve severe temperature variations.

Hydrothermally synthesized tungsten trioxide nanorods as NO2 gas sensors

“…Up to now, several methods have been reported for the synthesis of one-dimensional (1D) WO 3 nanostructures, including chemical vapour deposition (CVD) [15], flame synthesis [16], thermal evaporation [17], hydrothermal reaction [18,19], electro spinning [20], spray pyrolysis [21], microemulsion based solution synthesis [22] and electron-beam annealing [23]. Hydrothermal treatment can provide a cost-effective and morphology controllable route to obtain 1-D nanostructures, and hence has become an advantageous method.…”

CTAB-assisted hydrothermal synthesis of tungsten oxide microflowers

“…It is considered to be a promising material for multiple potential applications, including semiconductors for gas sensors, electrodes for secondary batteries, solar energy converters, and photocatalysts [3][4][5][6]. A number of synthetic methods have been developed for WO 3 such as a hydrothermal/solvothermal route [2,3,5,7], thermal processing [4], electric heating in vacuum [6], and physical/chemical vapor deposition process [8,9]. Among these, synthesis under hydrothermal conditions is a low-temperature, environmentally benign and low-cost route for preparation of nanosized oxide materials, and is becoming an increasingly attractive method [10].…”

Solvothermal synthesis and characterization of tungsten oxides with controllable morphology and crystal phase

“…Recently, the morphology controlled synthesis of tungsten oxide particles has attracted considerable attention [21][22][23]. One-dimensional (1D) tungsten oxides especially have attracted considerable interest due to their high aspect-ratio structure, large surface areas and unique physical properties, including optical, electronic characteristics and gas sensing effects [24][25][26].…”