Enhanced ammonia sensing performances of Pd-sensitized flowerlike ZnO nanostructure

We report the synthesis of flowerlike ZnO nanostructure using a facile hydrothermal process, and the investigation on the ammonia (NH3)-sensing properties of the pure and palladium (Pd)-sensitized flowerlike ZnO nanostructure. The phase purity, morphology, and structure of the pure and Pd-sensitized ZnO nanostructure are investigated. The characterized results reveal that the flowerlike ZnO has a wurtzite structure and is composed of numerous aggregated single-crystalline ZnO nanorods with a diameter of about 60 nm. Having fabricated gas sensors based on the pure and Pd-sensitized flowerlike ZnO, we find that the Pd-sensitized sensor exhibits a response of 45.7–50 ppm NH3 at 210 °C, which is about 8 times higher than that of pure ZnO at the optimal operating temperature of 350 °C. The enhanced NH3-sensing performance demonstrates that the significant decrease in optimal operating temperature and the distinct increase in response are attributed to the sensitization effect of Pd.