Cauliflower-Shaped ZnO Nanostructure for Enhanced NO2 Gas Sensor Application

Abstract

Herein, we report a facile synthesis of cauliflower-shaped ZnO structures through a hydrothermal method for efficient gas sensing applications. The ZnO structures were characterized by field emission scanning electron microscopy associated with energy dispersive spectroscopy (EDS), X-ray diffraction and Raman spectroscopy. XRD analysis revealed hexagonal wurtzite phase of ZnO crystals with excellent crystallinity and mean particle size of 45.50 nm. FESEM analysis showed cauliflower-like morphology composed of a large number of hexagonal nanorods. Cauliflower-shaped ZnO structures were used to device resistive sensor devices for NO2, NH3 and H2S gases. Gas responses for NH3 and H2S gases were not impressive even at high operating temperatures ranging from 200–450 °C. In contrast, for NO2 gas the responses were efficiently high even at very low operating temperatures. A maximum gas response of 431.36 was observed at very low operating temperature of 50 °C.