One-step synthesis of flower-shaped WO3 nanostructures for a high-sensitivity room-temperature NOx gas sensor

In this work, we report a one-step synthesis of spherical flower-shaped tungsten oxide (WO3) nanostructures by using polyethylene glycol (PEG) as a surfactant. The PEG played a crucial role in controlling the final morphology of the WO3 product. The structure and morphology of the product were characterized by carrying out XRD and SEM experiments. These characterizations indicated these three-dimensional flower-shaped nanostructures to be well crystallized, to have a uniform morphology with an average diameter of 3 μm, and to consist of many two-dimensional nanosheets. The flower-shaped WO3 particles exhibited excellent room-temperature NOx gas-sensing performance, including a sensitivity as high as 80%, a short response time of 4.5 s to 97 ppm NOx, and a low detection limit of 970 ppb. The excellent performance was due to the structure and morphology of the WO3 product.