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

Abstract

In this paper, highly dispersed hierarchical coral spheres of CeO₂/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 CeO₂ 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 CeO₂ nanoparticles on the surface of ZnO coral spheres and the heterojunctions between CeO₂ and ZnO, which produced abundant oxygen vacancies in the CeO₂/ZnO coral spheres.