Design synthesis of ZnO nanoparticles on Co3O4 nanosheet with rich oxygen vacancies for rapid detection of NO2 at room temperature

The solvothermal and wet chemical method was developed to synthesized the p-n heterostructures of the thin porous Co 3 O 4 nanosheets with ZnO nanoparticles. The resulting products were analyzed by using various characterization techniques. The results possessed that the presence of a large number of oxygen defects on the surface of Co 3 O 4 -ZnO-7 favors enhancing the NO 2 adsorption. Correspondingly, the formation of p-n heterojunction and the large surface area of the material itself increased the carrier density and exposed more active sites, which collectively boost the sensing performance to NO 2 . The sensor showed a high response of 45.7 (S = R a /R g ) to 100 ppm NO 2 at room temperature (RT = 25 °C), with a short response/recovery time (1.3/25 s), and the lower detection limit of the sensor reached 30 ppb, with good selectivity, reproducibility and stability. This study will offer the opportunity to develop new sensors with high response and fast response-recovery to NO 2 at room temperature.