Flower-like WO3 architectures synthesized via a microwave-assisted method and their gas sensing properties

The flower-like WO 3 structures were successfully synthesized by a simple calcination of W 18 O 49 nanowires obtained by a microwave-assisted solvothermal method . The as-prepared products were characterized by field emission scanning electron microscopy , X-ray powder diffraction, transmission electron microscopy , and nitrogen adsorption and desorption measurements. The results indicated that the building blocks of the flower-like structure were intercrossing single crystalline WO 3 nanorods with diameter of about 30–40   nm and length of about 300–400   nm. The gas sensing properties of as-prepared products to NO 2 and acetone were investigated. It was found that the sensor based on WO 3 nanostructures exhibited excellent selectivity and high sensitivity toward NO 2 at optimum temperature of 90   °C, giving a response of about 42 to 40   ppb NO 2 . Significantly, operating at 300   °C, the sensor's response and recovery time to 100   ppm acetone was only 1   s and 6   s, respectively.