Highly sensitive CO and ethanol nanoflower-like SnO2 sensor among various morphologies obtained by using single and mixed ionic surfactant templates

By using a simple surfactant-assisted pathway in hydrothermal method, tin dioxide with a diversity of well-defined morphologies was synthesized. This type of shape tailoring with morphologies of prism-like, mixture of nanoflower-like and prism-like, nanoflower-like, cubic-like and nanosheet-like was possible by varying the molar ratio of cationic and anionic surfactants. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The growth mechanism of these products was proposed. It was found that the formation of SnO2 with various morphologies could involve the role of preformed “seed” and the additives as a template used to control the growth rate of various facets of the preformed seeds. The gas sensors constructed by the SnO2 particles with different morphologies showed up to about two orders of magnitude with different sensor responses to both CO and ethanol. It was also found that the sensor based on nanoflower-like SnO2 sensors exhibited dramatically higher response for detecting CO and ethanol gas. Responses of the SnO2 nanoflower-like sensor to 50–1000 ppm CO were studied at 275 °C in an automated gas sensing system. A possible mechanism to explain the high sensing properties of these morphologies was proposed.