Formaldehyde Sensing Properties of SnO–Graphene Composites Prepared via Hydrothermal Method

Graphene (G) was prepared by reducing graphene oxide (GO) with hydrazine hydrate. SnO–graphene composites with different amounts of graphene were prepared via hydrothermal method. SnO–G composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the graphene content in the composites and the hydrothermal temperature on the gas-sensing responses of the materials to formaldehyde vapor were investigated. The gas-sensing selectivity of the sensor based on SnO–1% G (100 °C, 10 h) composite to five kinds of gases (1000 × 10−6) was also studied. The results revealed that the sensor based on SnO–1% G (100 °C, 10 h) exhibited high response to formaldehyde vapor when the operating temperature of the sensor was 133 °C and the response to 0.001 × 10−6 formaldehyde attained 3.9. The response time and recovery time for 0.001 × 10−6 formaldehyde were 24 and 12 s, respectively.