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 degrees 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. (C) 2018 Elsevier B.V. All rights reserved.