Surfactant assisted low temperature synthesis of nanocrystalline ZnO and its gas sensing properties

Vertically aligned ZnO nanorods, faceted microrods, nanoneedles and nanotowers were grown on glass substrates by a cost effective and low temperature aqueous chemical method. Various polymers viz. polyethylenimine (PEI), polyacrylic acid (PAA) and diaminopropane (DAP) ere used as structure directing agents. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern. The aligned ZnO nanorod formation takes place with the predominant orientation along (0 0 2) plane. These nanocrystalline ZnO samples were used to explore gas response properties for acetone, ammonia, LPG and ethanol. It is observed that the sensors based on DAP-directed nanoneedles showed higher response (90%) for acetone gas at 275 degrees C. The high acetone gas sensitivity and low operating temperature of ZnO nanoneedles can be attributed to the surface morphology. (C) 2010 Elsevier B.V. All rights reserved.