Synthesis and acetone sensing properties of ZnFe₂O₄/rGO gas sensors

Hollow spheres of pure ZnFe₂O₄ and of composites of ZnFe₂O₄ and reduced graphene oxide (rGO) with different rGO content were prepared via a simple solvothermal method followed by a high-temperature annealing process in an inert atmosphere. The X-ray diffraction analysis confirmed that the introduction of rGO had no effect on the spinel structure of ZnFe₂O₄. In addition, the results of field-emission scanning electron microscopy and (high-resolution) transmission electron microscopy indicated that the synthesized samples had the structure of hollow spheres distributed uniformly onto rGO nanosheets. The diameters of the spheres were determined as about 600-1000 nm. The gas sensing test revealed that the introduction of rGO improved the performance of the sensing of acetone to low concentration, and the ZnFe₂O₄/rGO composite gas sensor containing 0.5 wt % of rGO exhibited a high sensitivity in sensing test using 0.8-100 ppm acetone at 200 °C. The response of the 0.5 wt % ZnFe₂O₄/rGO sensor to 0.8 ppm acetone was 1.50, and its response to 10 ppm acetone was 8.18, which is around 2.6 times more pronounced than the response of pure ZnFe₂O₄ (10 ppm, 3.20). Moreover, the sensor showed a wide linear range and good selectivity.