Pompon-like Ni doped ZnO mesoporous microspheres for conductometric NO2 sensing properties at room temperature

Rapid detection of NO2 at room temperature plays a significant role in industrial production and daily life. Herein, the hierarchical pompon-like Ni doped ZnO (Ni-ZnO) mesoporous microspheres composed of abundant porous nanosheets were prepared by a facile solvothermal method. For Ni-ZnO composites based sensors, Ni doping not only reduced their working temperature but also enhanced their sensitivity. The test results suggested that the Ni-ZnO-0.03 based sensor showed outstanding gas-sensing properties toward 20 ppm NO2 at 25 celcius, such as high response (264), speedy response-recovery time (35, 93 s), excellent selectivity and long-term stability. Moreover, the sensor also possessed a low theoretical detection limit of 9 ppb toward NO2 at 25 celcius. The superior NO2 sensing properties of Ni-ZnO nanostructure composites could owe to the hierarchical and mesoporous structure, high specific surface area as well as increased oxygen vacancies.