Ultra-responsive and selective ethanol and acetone sensor based on Ce-doped Co3O4 microspheres assembled by submicron spheres with multilayer core-shell structure

The sensitive detection of ethanol and acetone is of great significance to address environmental toxicity concerns. Herein, a novel Ce-doped Co3O4 microsphere is precisely fabricated and assembled by abundant submicron spheres with multilayer core-shell configuration employing metal-organic frameworks (MOFs) as template and PVP as the structure-directing agent, and the formation mechanism of the microspheres with hierarchical structure is explored. Moreover, the gas sensing performance of Ce-doped Co3O4 sensor are investigated toward ethanol and acetone. The sensor based on CoCe0.025-350 (the molar ratio of CeCo = 0.025) microspheres exhibits remarkable responsiveness toward ethanol and acetone at relatively low operating temperatures (180 and 200 °C, respectively) and excellent long-term durability. The excellent sensing properties are firstly ascribed to the existence of abundant active sites and surface defects induced by Ce doping, and secondly originated from the hierarchical structure which benefits the absorption, diffusion of the gases on the sensor surface. Furthermore, detection limits as low as 0.1 ppm are achieved by the CoCe0.025–350 sensor. The sensing dynamics of the sensors are also investigated. The versatile strategy report herein can be employed to construct other transition metal oxides with excellent gas sensing properties.