Fabrication of SnO2–ZnO nanocomposite sensor for selective sensing of trimethylamine and the freshness of fishes

SnO2 nanoparticles and ZnO microrods were prepared and characterized by X-ray diffraction (XRD) and a field emission scanning electron microscope (FESEM). The results showed that the mean grain size of the SnO2 nanoparticles was 40 nm; the diameter of ZnO microrods was about 1–1.5 μm with a length between 8 and 10 μm. The gas-sensing properties of the SnO2 nanoparticles, ZnO microrods and the nanocomposite of SnO2 nanoparticles doped with 5–15 wt% ZnO microrods were investigated. The gas-sensing properties of the SnO2 nanoparticles were greatly improved by doping with the ZnO microrods. The SnO2–ZnO nanocomposite sensor showed high and quick response to trimethylamine (TMA) at 190–330 °C. This sensor showed the advantages of high selectivity, excellent sensitivity, strong stability and prompt response/recovery characteristics in detecting TMA at 330 °C. It could be used to detect the freshness of fishes.