Gas-Sensitive Properties of ZnO/ZnCo2O4 Made from Sodium Citrate Against Formaldehyde

Since cobalt-containing spinel oxides have good prospects for the detection of toxic gases, they also have great potential for applications in the field of gas sensors. However, ZnCo 2 O 4 -based gas sensors have the disadvantages of low response values and poor selectivity in formaldehyde detection. In this study, we attempted to prepare formaldehyde gas sensors by varying the addition of sodium citrate for hydrothermal synthesis of ZnCo 2 O 4 . During the fabrication process, it was found that an appropriate amount of sodium citrate content could produce ZnO on the surface of ZnCo 2 O 4 , and that the gas sensitivity of ZnO-ZnCo 2 O 4 to formaldehyde was better compared to that of pure ZnCo 2 O 4 . The sensor has a response rate of 17 at 20 ppm formaldehyde at 200°C. It also has good selectivity, repeatability, and stability. These results can provide foundational knowledge for the implementation of spinel oxide materials in the field of gas sensors.