Solvent thermal synthesis and gas-sensing properties of Fe-doped ZnO

In this study, pure ZnO microbullets, ZnO–ZnFe₂O₄ composite, and ZnO–Fe₂O₃–ZnFe₂O₄ composite with micron structured balloons, rods, and particles were prepared by a simple solvent thermal process using methanol or ethanol as solvents. The influence of solvents on the composition and morphology of the products was studied, and their gas-sensing properties were also investigated. The morphology of ZnO microbullets synthesized in ethanol is similar to but more uniform than that of ZnO microbullets synthesized in methanol. The Fe-doped ZnO synthesized in ethanol contains many micron particles homogeneously dispersing on the surface of the microbullets, which is composed of hexagonal wurtzite ZnO and franklinite ZnFe₂O₄, while Fe-doped ZnO prepared in methanol consists of micron structured balloons, rods, and particles, which is composed of hexagonal wurtzite ZnO, hematite Fe₂O₃, and franklinite ZnFe₂O₄. Compared with pure ZnO and ZnO–ZnFe₂O₄ composite, the ZnO–Fe₂O₃–ZnFe₂O₄ composite presented high response, rapid response/recovery characteristics, good selectivity, and excellent stability to acetone at relatively low operating temperature of 190 °C. This sensor could detect acetone in wide range of 1–1000 ppm, which was expected to be a promising gas sensor for detecting acetone.