Flower-like ZnO-Co3O4 heterojunction composites for enhanced acetone sensing

In this work, we successfully prepare the ZnO-Co3O4 heterostructure on a nanosheet hollow sphere structure. Due to the high redox activity of Co3O4, the fabricated sensor using 3 at% ZnO-Co3O4 hollow composite exhibits enhanced acetone sensing performance (S = 17.3-50 ppm) at a low operating temperature (150 degrees C), which is about 5.1 times higher than that of Co3O4-based sensor (S=3.4-50 ppm). Meanwhile, the ZnO-Co3O4 based sensor shows ppb-level detection limit (S=1.3 at 100 ppb). The reason for the higher sensitivity and lower detection limit of the sensor is that the formation of n-p heterojunctions reduces both the degree of upward band -bending and the surface hole concentration, that allows the sensor to have a higher gas response under the same surface sensing-reactions (surface charge transfer).

Automated summary

In this study, a ZnO-Co3O4 heterostructure was successfully prepared on a nanosheet hollow sphere structure. The fabricated sensor using 3 at% ZnO-Co3O4 hollow composite showed enhanced acetone sensing performance at a low operating temperature, which was about 5.1 times higher than that of Co3O4-based sensor. Additionally, the ZnO-Co3O4 based sensor exhibited a ppb-level detection limit. The improved sensitivity and lower detection limit of the sensor can be attributed to the formation of n-p heterojunctions, which reduces the degree of band bending and surface hole concentration.