Comparison of the Sensing Properties of ZnO Nanowalls-Based Sensors toward Low Concentrations of CO and NO2

This work focuses on the synthesis and gas sensing properties of ZnO nanowalls (ZnO NWLs) grown by a simple cheap chemical bath deposition method on a thin layer of aluminum (about 20 nm thick) printed on the Pt interdigitated electrodes area of conductometric alumina platforms. Post-deposition annealing in nitrogen atmosphere at 300 °C enabled the formation of a ZnO intertwined 2D foils network. A wide characterization was carried out to investigate the composition, morphology and microstructure of the nanowalls layer formed. The gas sensing properties of the films were studied by measuring the changes of electrical resistance upon exposure to low concentrations of carbon monoxide (CO) and nitrogen dioxide (NO2) in air. The sensor response to CO or NO2 was found to be strongly dependent on the operating temperature, providing a means to tailor the sensitivity and selectivity toward these selected target gases.