In this work, we synthesized Sm2O3/ZnO/SmFeO3 microspheres by a hydrothermal method combined with microwave assistance to serve as a methanol gas sensor. We investigated the effect on the microstructure at different hydrothermal times (12 h, 18 h, 24 h, and 30 h), and the BET and XPS results revealed that the specific surface area and adsorbed oxygen species were consistent with a microstructure that significantly influences the sensing performance. The gas properties of the Sm2O3-doped ZnO/SmFeO3 microspheres were also investigated. With a hydrothermal time of 24 h, the gas sensor exhibited excellent sensing performance for methanol gas. For 5 ppm of methanol gas at 195 °C, the response reached 119.8 with excellent repeatability and long-term stability in a 30-day test in a relatively high humidity atmosphere (55-75% RH). Even at 1 ppm of methanol gas, the response was also higher than 20. Thus, the Sm2O3-doped ZnO/SmFeO3 microspheres can be considered as prospective materials for methanol gas sensors.
Keywords: Adsorbed oxygen; Methanol gas; Specific surface area; p-n heterojunction.