Improved Gas-Sensing Properties of Graphene-CoFe2O4 Composite Prepared via Homogeneous Precipitation

Before studying the gas-sensing properties of graphene-CoFe₂O₄ composite, graphene-CoFe₂O₄ composite with different mixing ratio are prepared via homogeneous precipitation method with urea as precipitator and characterized by X-ray diffraction using CuKα. The experimental results reveal that the average grain size of CoFe₂O₄ with spinel-type structure is about 60 nm. The sensitive properties of pure CoFe₂O₄, 1%G-CoFe₂O₄, 2%G-CoFe₂O₄ and 5%G-CoFe₂O₄ are similar to the p-type semiconductor, and the sensor based on 5%G-CoFe₂O₄ shows the high sensitivity to ammonia, acetone vapor, formaldehyde vapor and acetaldehyde vapor with the temperature range from 80 to 300^oC. Especially, the sensor based on 5%G-CoFe₂O₄ shows the sensitivity as high as 3 to 1000 ppm formaldehyde vapor when the operating temperature of sensor is 180^oC. Thus, graphene CoFe₂O₄ composite may be applied to measure the formaldehyde vapor at low temperature if the selectivity and response are improved further.