Fabrication of novel hierarchical ZnO via ultrasonic assisted hydrothermal route and their gas sensing property

Novel hierarchical ZnO nanomaterials with castellated and turriform morphologies were successfully synthesized by ultrasonic assisted hydrothermal route. The morphology and structure of products were characterized by scanning electron microscopy and X-ray diffraction, respectively. The results show that as-prepared castellated ZnO microrods have six-equal axis symmetry features with the length of 2–4 μm and the diameter of about 1 μm, and ZnO with turriform morphology has radical branch structure with the diameter ranging from 500 to 700 nm. It is found that initial alkaline concentration of the solution plays a crucial role in determining two kinds of hierarchical morphologies by etching ZnO crystal during hydrothermal process. A possible formation mechanism of castellated and turriform ZnO microstructures is also proposed. Gas sensing of hierarchical ZnO to different gases was also examined. The result indicates turriform ZnO sensor has fast response properties and excellent selective resolution capability to C₂H₅OH gas.