Gas sensing properties of graphene–WO3 composites prepared by hydrothermal method

•The amount of graphene had an effect on the morphology of graphene–WO3 composites.•The optimum temperature of 0.1wt% graphene–WO3 sensor to acetaldehyde was 100°C.•0.1wt% graphene–WO3 sensor exhibited good selectivity to acetaldehyde at 100°C. Graphene–WO3 composites mixed with different amounts of graphene (0, 0.1, 0.5, 1 and 3wt%) were prepared by hydrothermal method at 180°C for 24h. The as-prepared graphite oxide, graphene and graphene–WO3 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR) and Raman spectroscopy, respectively. The effect of the amount of graphene in the composites on the gas-sensing responses and the gas-sensing selectivity of the materials was investigated. The experimental results revealed that the sensor based on 0.1wt% graphene–WO3 composite exhibited high response and good selectivity to acetaldehyde vapor at 100°C, the optimum operating temperature of this sensor to 1000ppm acetaldehyde vapor decreased from 180°C to 100°C comparing with that of pure WO3. The response time and the recovery time for 100ppm acetaldehyde vapor were 250s and 225s, respectively.