Sn3O4/rGO heterostructure as a material for formaldehyde gas sensor with a wide detecting range and low operating temperature

High-performance formaldehyde (HCHO) sensors are highly desirable for environmental gas monitoring and industrial gas analysis. Herein, an HCHO sensor featuring an excellent sensing response is proposed to offer a broad detecting range and operate at a low temperature, by exploiting a flower-like composite based on a heterostructure consisting of Sn3O4 and reduced graphene oxide (rGO). The Sn3O4/rGO composites with different rGO contents and the pure Sn3O4 are successfully prepared by a facile one-step hydrothermal method, and their corresponding sensing properties toward HCHO are systematically investigated. The Sn3O4/rGO sensors exhibit a highly improved sensing response at a relatively low temperature compared with the pure Sn3O4 sensor. In particular, the Sn3O4/rGO sensor utilizing 0.75 mg of the rGO realizes a much higher sensing response across the wide range of 1−1000 ppm HCHO, and its response is up to 44 when it is exposed to 100 ppm of HCHO at 150 °C. Additionally, the proposed Sn3O4/rGO sensor shows a good sensing selectivity, excellent reproducibility, and long-term stability. By analyzing the sensing mechanisms of the pure Sn3O4 and Sn3O4/rGO composite, the enhanced sensing properties for the Sn3O4/rGO sensor can be ascribed to the heterostructure between Sn3O4 and rGO, which gives rise to a considerable resistance variation when the sensor is exposed to air and HCHO.