Optimization ethanol detection performance manifested by gas sensor based on In2O3/ZnS rough microspheres

For traditional resistance-type gas sensor, introducing heterostructures was an effective way to enhance the sensing performance. In this work, heterostructure In2O3/ZnS composites material with rough spherical morphology was synthesized by two-step hydrothermal process in which pure ZnS microspheres acted as substrate for the coating of In2O3 nanoparticles. The obtained products were characterized by X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM), transmission electron microscopy (TEM), elemental mapping, X-ray photoelectron spectroscopy (XPS) and Brunauere-Emmette-Teller (BET) analysis. When compared with the sensors based on pure ZnS microspheres and pure In2O3 nanocubes, the In2O3/ZnS heterostructures sensor had an excellent sensing performance to ethanol, and the response to 100 ppm ethanol was 11.7 which was nearly 2 times higher than that of pristine ZnS sensor (about 5.87) and 1.6 times larger than that of pristine In2O3 sensor (about 7.309) at the optimal operating temperature of 260 °C. The response/recovery time of In2O3/ZnS sensor were 21/34 s, whereas the pure samples were 32/59 s (ZnS) and 35/38 s (In2O3) respectively. The main mechanism for the enhanced performance of In2O3/ZnS composites sensor were the formation of heterojunction and synergistic effect between In2O3 shell and ZnS core, meanwhile, the large specific surface area was also a contribution factor.