Synthesis of hierarchical shell-core SnO2 microspheres and their gas sensing properties

Using SnSO4,D-glucose,urea and water,hierarchical shell-core SnO2 microspheres were successfully synthesized via a simple hydrothermal method.The characte rization results showed that the sizes of asprepared SnO2 microspheres were 0,6-1μm,with shell thicknesses of 4060 nm,The shell and large core of the SnO2 microspheres were all comprised of the same basic rice-like nanoparticles with diameters of 16-25 nm and lengths of 16-45 nm.Further investigaton showed that the glucose and urea served as structural guiding agents,and urea facilitated the formation of the hierarchical structure.The as-prepared SnO2 nanomaterials were used to fabricate a gas sensor with an electrode blade used for the gas sensitivity tests,The hierarchical shell-core SnO2 microspheres exhibited high sensitivity and selectivity toward ethanol,with a responsivity of 63.8 for 50 ppm ethanol at 250℃,while the response and recovery time were 7 s and 28 s,respectively.Moreover,the responsivity of the materials showed good linearity at ethanol concentrations from 500 ppb to 10 ppm.The simple synthetic method,environmentally-friendly raw materials,and excellent gas sensitivity demonstrate that the as-prepared SnO2 nanomaterial has great potential applications for the sensing of ethanol gas.