Facile and template-free fabrication of hierarchical coral spheres for acetone gas sensors.

In this paper, highly dispersed hierarchical coral spheres of CeO 2 /ZnO have been constructed through a facile template-free hydrothermal strategy, followed by an annealing treatment. The resulting coral spheres exhibit enhanced activity for acetone sensing compared with CeO 2 or ZnO as well as excellent cyclability and long-term stability. At the optimum working temperature of 245 °C, by controlling the ratio of Ce/Zn, the highest response of the coral spheres towards 100 ppm acetone is up to 145, which is about 5.5 times that of ZnO coral spheres. The significantly improved gas sensing activity may be ascribed to the well-dispersed and assembled CeO 2 nanoparticles on the surface of ZnO coral spheres and the heterojunctions between CeO 2 and ZnO, which produced abundant oxygen vacancies in the CeO 2 /ZnO coral spheres.