Preparation And Gas Sensing Properties Of Interconnected Macroporous SnO₂ Based Composite Materials

With the development of social life and production,the demand for detecting flammable,explosive,toxic and harmful gases is getting higher and higher.Therefore,higher requirements are put forward for gas sensors,especially for gas sensitive materials which constitute gas sensors.In order to improve the sensitivity of gas sensitive materials,it is necessary to modify the gas sensitive materials by compounding,doping,modifying and structure modification.In this paper,PS microspheres were prepared by emulsion polymerization,and porous macroporous SnO₂/ZnO composites and SnO₂/Hollow Carbon Spheres materials were prepared by using the PS as template.The gas sensing properties such as working temperature,sensitivity,selectivity,response and recovery time and stability were studied systematically.The results are as follows:1.PS microspheres were prepared by emulsion polymerization.The effects of polymerization temperature,monomer dosage,emulsifier concentration and initiator concentration on the average particle size and coefficient of variation of PS microspheres were systematically studied.The results showed that the optimum polymerization temperature of PS microspheres was 80⁹0?.The particle size of PS microspheres increased with the increase of monomer consumption and the decrease of emulsifier concentration.The coefficient of variation?Cv?increased with the increase of emulsifier concentration.The concentration of initiator>0.02%,coefficient of variation Cv<5%,monodispersity are good.2.Macroporous SnO₂/ZnO composites were successfully prepared by PS microspheres and SnO₂ nanoparticles,impregnated with Zn?NO₃?₂ alcohol solution and calcined to remove template PS microspheres.SEM showed that the macroporous SnO₂/ZnO composites had good integrity,orderliness andpore permeability.3.The hollow carbon spheres were prepared by using sulfonated PS microspheres as templates and phenolic resin as raw materials.SnO₂/Hollow Carbon Spheres were successfully prepared by adding hollow carbon spheres into SnO₂ hydrothermal synthesis process.4.The gas sensitivity of macroporous SnO₂/ZnO composites was studied.The results showed that the macroporous materials obtained by impregnating 1.0 mol/L Zn?NO3?2 alcohol solution with 261 nm PS microspheres as template had the highest sensitivity to formaldehyde,and the response value was 360 to 200 ppm formaldehyde at the optimum operating temperature of 220?,which showed good selectivity to formaldehyde.5.The study on the gas sensing properties of SnO₂/Hollow Carbon Sphere composites shows that the sensitivity of SnO₂/hollow carbon sphere composites to 200ppm ethanol is 27.27%higher than that of pure SnO₂ nanoparticles at the optimum working temperature of 220?,and the composites have good selectivity to ethanol and triethylamine.