Ppb-Level Xylene Gas Sensors Based on Co3O4 Nanoparticle-Coated Reduced Graphene Oxide(rGO) Nanosheets Operating at Low Temperature

Xylene is a toxic carcinogen, which may irritate eyes and respiratory tract, or damage the central nervous system. However, the traditional semiconductor gas sensor can only detect the ppm level of xylene gas, which cannot meet the building air quality monitoring requirements. Therefore, the development of low concentration gas detection of xylene gas sensor is necessary. In this article, a one-step hydrothermal method for the preparation of reduced graphene oxide (rGO)/Co3O4nanocomposite was reported. Then, rGO/Co3O4nanocomposites were characterized by various characterization methods. It was found that the structure of cobalt tetroxide (Co3O4) nanoparticle-coated rGO nanosheets was successfully synthesized. Specific internal morphology could be seen by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Then the gas sensor made of rGO/Co3O4nanocomposite material was tested for its gas sensitivity performance. A series of properties such as repeatability and stability of the material were tested. According to the test results, the sensitivity of 1rGO/Co3O4(3.35 wt%) to xylene gas was better than that of 2rGO/Co3O4(5.54 wt%) and pure Co3O4, and the optimal working temperature of rGO/Co3O4to 50 ppm xylene was 175 °C, which was 50 °C lower than that of pure Co3O4. In addition, the rGO/Co3O4gas sensor could also detect xylene gas with a minimum concentration of 1 ppb. Finally, the gas sensing mechanism of the gas sensor for xylene gas was analyzed.