Farming of maize-like zinc oxide via a modified SILAR technique as a selective and sensitive nitrogen dioxide gas sensor

Abstract

Novel hierarchical nanostructures of metal oxides have enormous potential in various applications. In this report, novel nanostructured maize-like ZnO was synthesized via a facile and economical modified successive ionic layer adsorption and reaction (M-SILAR) method and subsequent heat treatment at 300 °C for 30 min as a highly-sensitive NO₂ gas sensor. The M-SILAR technique described uses two bath solutions instead of the conventionally used four bath solutions. Their structural, morphological, and optical properties have been thoroughly characterized using advanced techniques such as X-ray diffraction, field-emission scanning electron microscopy and photoluminescence spectroscopy. The obtained hexagonal wurtzite ZnO structure appears as the hierarchical maize corn-like morphology with nano-granules. The ZnO maize based sensor contains numerous active sites, which afford beneficial conditions for gas adsorption and diffusion. Moreover, the synthesized sensor was proven to be an excellent NO₂ sensing material with high selectivity, superior sensitivity, and good response/recovery at relatively a low operating temperature. The peculiar structure of our sample, the preparation method and its nitrogen dioxide detection have wide application prospects.