In situ growth of ZnO nanorods array film on the surface of ITO for low temperature detection of NOx gas

Nitrogen oxides are one of the most harmful gases and highly toxic to human health if inhaled at moderate atmospheric concentrations or above (10–20 mmHg). Sensing NOx is one of the most challenging tasks at low temperature levels and room temperature. The ZnO nanostructures were successfully synthesized by hydrothermal method. The wettability and gas sensitivity of the ZnO nanorods array film were studied. The results show that the ZnO nanorods array film is hydrophobic by adding KCl. In addition, the ZnO nanorods array film shows a positive response to NOx. The gas sensing performance shows that the sensor response based on ZnO nanorods array film has a linear relationship with the concentration of NOx in the range of 0.1–3 ppm. It has good reproducibility and selectivity. The maximum sensitivity to NOx was obtained at an operating temperature of 120 °C. The response of the sensor is 25 when the concentration of NOx is 3 ppm.