Synthesis and application of high-oriented crystalline yarn-ball-like tungsten oxide nanowires

• Main Authors: Wen-hui Chang, 張汶慧
• Other Authors: Shiow-huey Chuang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/74159660111958028644

碩士 === 國立高雄大學 === 應用化學系碩士班 === 100 === In recent years, tungsten oxide (WO3-x) has attracted the interest of researchers because of its unique chemical and physical properties, such as its photocatalyst activity and sensor, electrochromic, thermoelectric, ferroelectric, field electron emission, and gaschromic properties. At room temperature, tungsten oxide can exist in several stable crystalline states; its diverse morphology also promotes wider applications and can enhance its properties. This study examines the specific tungsten oxide produced during the crystalline phases of tungsten oxide using the solvothermal method without an assistant agent, but with the precursors WCl6 and 2-propanol. This unique form of tungsten oxide then underwent heat treatment and the products obtained were classified using X-ray diffractometer, Transmission electron microscopy, Scanning electron microscopy, Micro-Raman spectroscopy, Fourier transform infrared spectroscopy and Surface area porosity analyser. The study results show that the product obtained using tungsten oxide treated with the solvothermal method has a morphology of yarn-ball-like nanowires, with a width of 5 to 15 nm and a length of tens of micrometres. After the yarn-ball-like tungsten oxide underwent heat treatment, the product was transformed into nanoparticle lumps; the size of the nanoparticles was 20 to 80 nm. The growth process of tungsten oxide can be divided into two parts. The first part is the growth of tungsten oxide nanowires, known as Ostwald ripening. The second part is the formation of nanoparticle lumps, known as the fusion process. Further research on the sensing characteristics of products show that products obtained under a conventional heat treatment 400oC at room temperature, have a NO gas sensing selectivity of up to 70.3, making them excellent sensing materials.