Gas Sensing Properties Of 3D SnS₂ Hierarchical Nanoflowers Synthesized By Hydrothermal Method

Ammonia?NH₃?,a widely used industrial chemical reagent,is highly irritating to the respiratory tract when it is too high in the workplace.It can cause vomiting,headache and pulmonary edema.According to the OSHA standard,the threshold for ammonia in the workplace is 50 ppm.In the past few decades,most gas-sensitive materials are based on metal oxides,such as ZnO,SnO₂,WO₃,CoFe₂O₄,etc.But they have some defects,such as high operating temperature,poor selectivity,and inability to monitor low-concentration ammonia gas in time.Therefore,it is important to explore a gas sensor that can monitor the low concentration ammonia gas in time.In order to broaden the research field of gas sensor,this paper uses metal sulfide SnS₂ as the main material,and uses ZnSn?OH?₆ as precursor to prepare 3D SnS₂ hierarchical nanoflowers by hydrothermal method.The morphology,specific surface area and electrical conductivity of the SnS₂ material were modified to improve the gas sensing performance.The main contents are as follows:1.In this paper,3D SnS₂ hierarchical nanoflowers with ZnSn?OH?₆ hollow nanospheres as precursors prepared by two-step hydrothermal method.The possible formation mechanism was investigated by studying the morphology at different reaction times.Gas-sensitivity tests have shown that the gas-sensitive material has a response of 9.6 to 50 ppm ammonia at a lower operating temperature of 160°C,a lower test limit of 5 ppm,and good selectivity to ammonia.Therefore,3D SnS₂ hierarchical nanoflowers exhibit good gas sensitivity to low concentration ammonia gas and can be used as candidate gas sensing materials for monitoring low concentration ammonia gas.2.In order to improve the gas sensitivity of the above 3D SnS₂ hierarchical nanoflowers,it was doped with rare earth elements.After 3D SnS₂ hierarchical nanoflowers after Pr doping,the grain size of the sample is reduced,and the specific surface area is higher,which is beneficial to the improvement of gas sensing properties.The gas sensitivity test showed that Pr-SnS₂ has a better gas sensing property to ammonia gas.At a lower operating temperature of 160°C,the response of Pr-SnS₂ to50 ppm ammonia was 14.3.Its response value increased by 1.7 times compared with the SnS₂ sample.Meanwhile,it has a faster response/time?6 s/13 s?.Experiments show that Pr doping effectively improves the gas sensing properties of 3D SnS₂hierarchical nanoflowers.