Study On Gas Sensitive Properties Of WS₂ Nanomaterials Via Electrospinning

Gas sensor,used to detect a variety of toxic or harmful gases,such as ammonia,hydrogen sulfide,sulfur dioxide,is closely linked to people’s daily life,which occupies an important position in the field of national science and defense construction.It has become the essential in today’s social development that building a high-performance gas sensor whicn can quickly detect the poisonous,the harmful,the flammable and the explosive gas in the air.Among them,semiconductor gas sensors were most widely researched in recent years,who became the research hot spot because of its advantages of simple structure,convenient use and low price,.In the semiconductor gas sensor researchs,their high performances are people’s pursuit of goals,such as good sensitivity,fast response&recover time,the recognition ability of one special gas,etc.However,these important features mainly depends on the micromechanism and chemical and physical properties of the surface of gas sensitive materials.Traditional gas sensitive material,has a larger grain or hole size,leading to small specific surface area,thick film,which is not conducive to the preparation of high-performance gas sensitive elements.Therefore,the main task of building high-performance gas sensor is finding a more efficient gas sensitive material.Tungsten sulfide is a typical transition metal sulfide,whose structure is similar to the layered structure of graphene,which makes it has special properties in catalysis,optics,electricity,and has extensive applications in the field of tribology,catalysts,etc.Nanosized WS₂ is a kind of excellent performance of gas sensitive material which has a large surface area,a stable structure,a strong oxidation resistance ability under high temperature.It is of great significance to conduct research and improvement for its gas sensitive properties.In the present work,High quality of WS₂ nanomaterials has been successfully prepared by electrostatic spinning technology combined with the annealing treatment.Since precious metal nanoparticles doped WS₂ nanomaterials can promote gas sensitive material surface adsorption capacity of the target gas molecules,the gas sensitive properties of not doping and doping layered nanosized WS₂ were tested and compared.As the detection results can be known,WS₂ nanomaterials gas sensor has an excellent response sensitivity,good selectivity and rapid response and recovery characteristics for ammonia under the best working temperature of 220℃.The response characteristics of gas sensitive element can be improved by the doping of Ag particles.The main research details are as follows:（1）It was conducted that synthesis of WS₂ nanomaterials by electrospinning combined with annealing treatment and the characterization of the structure and morphology.The researchs which mainly cover the configuration of the electrospinning precursor solution,the electrospinning process,the vulcanization process were included in the whole process.（2）Heater-type gas sensor based on nanosized WS₂ was successfully prepared,which mainly cover the cleaning of ceramic tube,the preparation of gas sensitive slurry,the coating and sintering of sensitive film,the fixing of electrode,etc.（3）In order to facilitate gas-sensing properties testing,we designed a test chamber easily based on gas sensitive element and set up a simple gas sensor testing circuit combining with some devices such as dc power supply and sourcemeter.（4）Ammonia,acetone,anhydrous ethanol gas for experiments were prepared.The gas sensitive properties was tested after using a syringe by a static injection.According to the test datas,we could analyze the gas sensitive properties of nanosized WS₂ gas sensitive element.（5）For improving the gas sensitivity,Ag doped nanosized WS₂ layers was prepared by multiple alcoholize method,and compared to not doped nanometer WS₂ layer flakes,Ag-WS₂ showed better response characteristics,select properties and had a higher sensitivity on the target gas.（6）Explains of the charge transfer and conductivity change process on the surface of sensitive materials through the analysis of the existing test datas and the related theory knowledge combined with the heater-type working principles of the gas sensor and gas sensitive film microstructure.