Core-double shell ZnO@In2O3@ZnO hollow microspheres for superior ethanol gas sensing

Core-double shell-structured ZnO@In2O3@ZnO microspheres consisting of ZnO hollow microspheres, an In2O3 interlayer, and a ZnO outer layer were synthesized by decorating In2O3 and ZnO on the surface of ZnO hollow microspheres. The ZnO hollow microspheres with a size of 1.4 mu m provided a good matrix for the adhesion of In2O3 and ZnO. Both In2O3 and the ZnO shells have a loose microstructure, which provided numerous gas diffusion channels and active sites for gas diffusion and gas sensing reaction. The surface defects and electronic structure of ZnO and ZnO@In2O3@ZnO were examined by photoluminescence (PL) and ultraviolet photoelectron spectroscopy (UPS). The gas sensing properties of the ZnO hollow microspheres, ZnO@In2O3 core-shell microspheres, and ZnO@In2O3@ZnO core-double shell microspheres were compared using ethanol as the target gas. The response of ZnO@In2O3@ZnO toward 100 ppm ethanol was 453.2 at the optimum operating temperature of 200 degrees C, which was 2 and 30 times higher than that of ZnO@In2O3 and ZnO. Even at a concentration of 1 ppm, the response of ZnO@In2O3@ZnO reached 53.2, indicating its excellent gas-sensing performance at low concentrations. The superior gas sensing properties of ZnO@In2O3@ZnO were attributed to its high specific surface area, abundant surface defects, and radial electronic modulation mechanism.

Automated summary

Core-double shell-structured ZnO@In2O3@ZnO microspheres were successfully synthesized by decorating In2O3 and ZnO on the surface of ZnO hollow microspheres, exhibiting excellent gas sensing properties with high response to gases like ethanol, especially at low concentrations. This superior gas sensing performance was attributed to its high specific surface area, abundant surface defects, and radial electronic modulation mechanism.