Study On The Synthesis?Exfoliation And Sensing Properties Of SnS₂ Layer

With the rapid development of society and great progress of industry,harmful gases produced in industrial and chemical production become more and more.Ammonia is one of the most harmful gas.High ammonia concentration in the air can cause serious damage to human body health,and also has certain explosion hazard.Therefore it is very important to detect ammonia in daily life and industrial production effectively and accurately.While traditional sensitive materials are almost metal oxide,which often need to work at high temperature,in the detection of ammonia gas sensor,and it is difficult to reduce the working temperature while keeping the device good response.Therefore researchers are focusing on the gas sensing materials which can work under room temperature with good sensing performance,or work normally under complex conditions.With a graphite layer structure as well as a narrow optical band gap?about 2.2eV?,tin disulfide,has already been applied in many fields.However,there is rarely reports on tin disulfide in gas sensing field.In this paper,the relevant research for tin disulfide in ammonia gas sensing properties has been done.At first stannous chloride hydrate and thioacetamide is used as a source of tin and sulfur source to synthesis thick-layered SnS₂ nanomaterial by hydrothermal method.The material's response to ammonia is low under the dark state.In order to investigate the adsorption of ammonia in the material surface,light was applied since SnS₂ has a narrow optical band gap.The material's light response under nitrogen atmosphere is tested in different colored light,showing that the response in blue light is best,which could be attributed to that the blue light photon energy just slightly larger than SnS₂ optical band gap,which would lead to the most effective light absorption.So blue light was chosen as light source.And the material's photocurrent is tested under different concentrations of ammonia.Excellent response is obtained.This is caused by the oxidation of the photo generated holes,promoting ammonia molecules losing electron on the surface of materials and leading to carrier concentration in the material rise.The ultrathin SnS₂ nanostructures is synthesized successfully by Lithium ion intercalation method,and has been tested ammonia gas sensor at room temperature.The results show that the material exfoliated show commendable response for ammonia.This could be attributed to sulphur vacancy on the exfoliated material's surface.Reducing ammonia molecules can directly react with positive charged Sn⁴⁺ion through sulphur vacancy without overcoming potential field of S^2-ion,thus reducing adsorption energy of Ammonia molecule and incresing the response.In addition the material shows good stability and high selectivity,illustrating the huge potential and application prospect of ultrathin SnS₂material in gas detection field.