The Fabrication And Gas Sensing Performance Of Porous Oxide Microspheres Produced Using Spray Drying

With the development of modern economy and society,industrialization has brought people great value and many environmental pollution problems,among which poisonous and harmful gases are discharged.Gas sensor plays an important role in detecting inflammable,toxic and harmful pollution gas.Tin dioxide,as an important wide-gap semiconductor material,has been widely used in gas sensor,but its sensitivity and selectivity need to be further improved.As a surface resistance controlled gas sensitive material,the sensitivity can be improved by increasing the specific surface area of the material,and the gas selectivity can be improved by ion modification.Therefore,this paper mainly prepared porous structure tin oxide by spray drying method and template method,and then on the basis of the above studies,further used metal ions to modify tin dioxide,and studied the porous structure tin dioxide and modified tin dioxide gas sensitive properties.The research results are as follows:1.Firstly,tin oxide microspheres were prepared by spray drying method.SnO2 porous microspheres with mesoporous structure were prepared by spray drying and glucose was introduced as pore forming agent.The particle size of the porous SnO2 microsphere prepared was about 2-5 μm,with a grain size of 11 ±0.5 nm.The specific surface area of the porous SnO2 microsphere was 39.6 m2/g,and the size of the main pore diameter was about 12.3 nm.The porous SnO2 material showed good gas sensitivity to n-butanol.The sensitivity of 300 ppm n-butanol at 300℃ was 105.3,the response time was 50 s,and the recovery time was 25 s.In addition,the preparation of In2O3 microspheres and ZnFe2O4 microspheres and their gas-sensitive properties were studied by this method.The results showed that:In2O3 porous microspheres with the size of 2-5 μm,which showed good selectivity for n-butanol,were synthesized.At 300℃,the sensitivity of 300 ppm n-butanol was 37,the response time was 40 s,and the recovery time was 18s.The size of the synthesized ZnFe2O4 porous microsphere was 2-4 μm,and the synthesized ZnFe2O4 porous microsphere also showed good selectivity for n-butanol.The sensitivity of 300 ppm n-butanol at 300℃ was 19.6,the response time was 36s,and the recovery time was 15s.2.The above mesoporous structure tin oxide microspheres were selected and modified.Graphene and gold particles were used to modify SnO2.The results showed that the addition of graphene did not change the structure of the synthesized microspheres.The size of graphene-modified SnO2 microspheres was 2-3 μm,showing a high sensitivity of 110 to 300 ppm n-butanol.Compared with the non-doped SnO2 materials prepared by spray drying method before,the sensitivity of graphene-doped SnO2 was not significantly improved.In addition,Au modified SnO2 microspheres were also studied,and porous microspheres with sizes of 2-5 μm were prepared.The specific surface area of the porous microspheres prepared was 31.3 m2/g,and the pore size was mainly distributed at 61.7 nm.Compared with undoped SnO2,doped SnO2 with gold particles The gas-sensitive properties show high sensitivity.The sensitivity of Au doped SnO2 prepared at 300℃ to 300 ppm n-butanol is 154,the response time is 50 s,and the recovery time is 35 s.The modification of gold particles is conducive to improving the gas-sensitive performance of SnO2 microspheres.3.In addition,the mesoporous SnO2 was prepared by biological template method.SnO2 with pomelo peel structure was successfully prepared by freeze-drying,titration,hydrothermal and calcination,using part of pomelo peel as biological template.The prepared pure SnO2 showed a very high sensitivity to 300 ppm n-butanol and methanol(1216.842/1966:971).However,the response recovery time was also extended:1084 s/591 s and 2144 s/935 s.In order to further improve the response recovery time,the experiment adopted NiO modification to shorten the response recovery time of SnO2.The research results showed that the 0.5%NiO doped SnO2 showed better gas sensitivity performance through the comparison of different doping amounts.At 150℃,the sensitivity of 300 ppm n-butanol was 1556.208,and the response recovery time was 193 s/651s.