On the high response towards TEA of gas sensors based on Ag-loaded 3D porous ZnO microspheres

In this paper, an ultra-high response and fast response/recovery triethylamine (TEA) gas sensor is fabricated by growing Ag nanoparticles on the surface of hierarchical 3D porous ZnO microspheres (Ag-ZnO) via a green and facile precipitation method. The morphological characterizations reveal that the hierarchical 3D ZnO micro spheres are assembled by large numbers of thin and porous nanosheets. The sizes of the microspheres are 3-5 m and the thickness of these porous nanosheets is about 20 nm. Gas sensing measurements show that the Ag-ZnO gas sensor exhibits superior TEA sensing performance. Its response to 100 ppm TEA is 6043, which is 14.8 times higher than that of pure ZnO sensor. Besides, its optimal working temperature decreases from 230 to 183.5 degrees C compared with the pure one. And the Ag-ZnO gas sensor also exhibits fast response/recovery rate (about 1 s and 60s, respectively). Furthermore, the Ag-ZnO gas sensor shows no obvious degradation through a testing period of 30 days. The superior TEA sensing performances could be attributed to the structural advantage of hierarchical 3D porous microsphere, as well as the synergistic effects of Ag nanoparticles and ZnO microspheres.