Highly sensitive and low detection limit of ethanol gas sensor based on hollow ZnO/SnO2 spheres composite material

Heterostructure ZnO/SnO2 composites material with a hollow nanostructure was synthesized by solution method. The obtained products were characterized by X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that ZnO nanoparticles could be clearly observed on the surface of SnO2 hollow spheres and the surface oxygen chemisorbed ability of ZnO/SnO2 composites was much higher than that of single-component SnO2. The as-synthesized composites as sensing material was investigated and the results revealed that such composites had an excellent sensing performance to ethanol, and the response to 30 ppm ethanol was nearly 7-times higher than that of pristine SnO2 at its optimum temperature. Moreover, it is noteworthy that such gas sensor showed a low detection limit (ppb-level). The enhanced sensing properties might be attributed to the formation of heterojunction and synergistic effect between SnO2 and ZnO.