Rational Design of Co-Loaded ZnO Hollow Spheres and Their Application in an Ethylene Glycol Sensor With High Sensitivity

Ethylene glycol (EG) is a colorless and odorless compound that can cause serious health problems following prolonged inhalation. Therefore, accurate detection of EG can be essential. However, the current EG gas sensors, especially those based on ZnO, are limited by factors such as high operating temperature and low response value and thus cannot meet the actual performance requirements. In this work, different cobalt-content Co₃O₄/ZnO heterojunction hollow spheres are synthesized through a two-step solvothermal method. Compared with pure ZnO microspheres, the optimal operating temperature of the Co₃O₄/ZnO-1 sensor is significantly reduced, to only 150 °C. Moreover, the Co₃O₄/ZnO-1 sensor demonstrates a remarkably high response to EG (S = 648 and 100 ppm), with response and recovery times of 24 and 19 s, respectively, which enables near real-time detection. The sensor also shows excellent selectivity against various interfering gases and long-term operational stability. The research results show that this sensor can achieve rapid and highly sensitive detection of EG at relatively low temperatures without the need for any additional auxiliary conditions. Its excellent selectivity and long-term stability give it great potential for application in numerous fields such as safe production.