The effect microstructure on the gas properties of Ag doped zinc oxide sensors: Spheres and sea-urchin-like nanostructures

Controllable ZnO architectures nanostructures were synthesized via a facile hydrothermal method and the morphologies achieved included spheres and sea-urchin-like nanostructures with the different reaction time of 16 h and 24 h. The structural, elemental composition and morphology were investigated by X-ray diffraction (XRD), energy-dispersive X-ray detector (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). The XRD studies demonstrated that the these samples had well crystallized and showed that they were composed of ZnO nanoparticles and Ag ions were also successfully doped into the ZnO lattice. The SEM and TEM studies indicated that the samples of spheres and sea-urchin-like nanostructures were obtained successfully. In addition, the sensor based on this sea-urchin-like ZnO nanostructures exhibited perfect sensing performance toward ethanol with high sensitivity and quick response than the sensor based on the ZnO nanosphere sample owing to its larger specific surface area, which were showed by BTE. The gas sensing results showed that the response value of 1 wt% Ag-doped sea-urchin-like ZnO sensor to 10 ppm ethanol was 22 at the optimum operating temperature of 260 °C. Finally, the possible formation mechanism of sea-urchin-like ZnO nanostructures and the gas-sensing mechanism of sensors were discussed, too.