The Gas-sensing Characteristic Of Two-dimension Transition Metal Sulfide

As a transition metal sulfide material,molybdenum disulfide and tungsten disulfide are used in different fields,such as gas sensor.due to its graphene-like structure and other excellent characteristics in various aspects.There is a deep research space and development research prospects in molybdenum disulfide.With the needs for the quality of our life and our environmental safety become more and more important,the requirements of monitoring pollution gas in life is also increasing.With the excellent characteristics of lower cost,lower power consumption,higher sensitivity,and higher recognition,gas sensors based on semiconductors have been extensively studied and used in daily life and production.Compared with traditional gas-sensing materials,there is a larger specific surface area in two-dimensional semiconductor gas-sensing materials,and the surface can have more sites for gas molecules to adsorb,and theoretically have better gas-sensing performance.Molybdenum disulfide and tungsten disulfide,as a two-dimensional transition metal sulfide gas-sensitive material,have excellent gas-sensitive properties.This article aims to test and analyze the gas sensitivity of molybdenum disulfide and tungsten disulfide through experiments;explain and improve the gas sensitivity of molybdenum disulfide through theoretical calculations on the basis of experimental analysis.Ammonia and nitrogen dioxide are common harmful gases in life.Long-time inhalation of harmful gases will not only cause great harm to the human health,but also cause olfactory fatigue,making people difficult to detect unknown risks.For this reason,this article mainly studies the gas sensitivity of molybdenum disulfide and tungsten disulfide to ammonia and nitrogen dioxide through experiments;in terms of theoretical calculations,it mainly studies the gas sensitivity of mono-layer molybdenum disulfide,and It’s performance been partially improved.This paper mainly includes the following aspects of work:1.We prepared gas sensors of molybdenum disulfide and tungsten disulfide:disulfide and tested them.We found a better temperature of the device,with the change of temperature,the response of device turned higher and then turned down.Under the heating condition of 50℃,the response to 10ppm nitrogen dioxide is 2.71 and 4.82.When the adsorbed gas is ammonia,the resistance of the gas sensor increases;when the adsorbed gas is nitrogen dioxide,the resistance of the gas sensor decreases.This is because when the gas sensor absorbs the reducing gas ammonia,electrons are transferred from the ammonia to the surface of the gas sensor,resulting in a decrease in the hole concentration of the element and an increase in resistance.When the oxidizing gas nitrogen dioxide is adsorbed,the electrons are transferred from the gas sensor The surface transfer to nitrogen dioxide leads to an increase in the hole concentration of the device and a decrease in resistance.It is concluded that the gas sensor is a p-type semiconductor.2.A mono-layer molybdenum disulfide adsorption model for ammonia,nitrogen dioxide and hydrogen sulfide gas is constructed.When the three gases are adsorbed on a single-layer molybdenum disulfide,a certain amount of electron transfer occurs,and ammonia and hydrogen sulfide are in the adsorption process.The loss of electrons in the medium is about-0.0143 and-0.020,respectively,which is reductive;nitrogen dioxide gains electrons in the adsorption process,the size is about 0.1384,which is oxidizing.And the number of electron transfers of nitrogen dioxide is greater than that of the first two gases.3.An anti-site defect model in which a single molybdenum disulfide replaces a single sulfur is constructed,the adsorption performance of the single-layer molybdenum disulfide on nitrogen dioxide is improved,and a larger The size of the electron transfer is about 0.3394;compared with the defect-free adsorption model,a larger number of electron transfers are obtained.4.A device model with a mono-layer of molybdenum disulfide adsorbing ammonia and nitrogen dioxide was constructed,and the current under a specific bias voltage was calculated.Under the same bias voltage,the resistance through the device model with nitrogen dioxide adsorption is lower than that of the non-adsorption model and lower than the resistance of the ammonia adsorption model,and the results are consistent with the experiment.