| With the rapid development of industry,a large number of toxic and harmful gases have been produced in the human environment.As an important tool to detect the composition and concentration of gases,gas sensors have been widely used in various fields of industry and life.Among different semiconductor gas sensors,metal oxide gas sensors are widely used in many applications because of their high responsiveness,quick response recovery and wide measurement range.However,the operating temperature of the gas sensor is too high so that the further development is hindered immensely.In recent years,new semiconductor materials have been developed rapidly.The two-dimensional nanomaterials just like graphene and Mo S2 have been continuously expanded in gas sensors because of their excellent gas adsorption capacity and large specific surface area and other excellent chemical and physical characteristics.In this paper,based on the existing research reports,we successfully prepared the Mo S2/rGO and Au-Mo S2/rGO composites by changing reaction temperature,reaction time and other technological parameters,using the improved electrochemical stripping,hydrothermal and ion sputtering methods.At the same time,the gas sensing properties and gas-sensitive mechanism of the composite are systematically studied.The main research contents of this paper as follows:1. Firstly,graphene oxide?GO?was prepared from flexible carbon paper using an improved electrochemical stripping method.Under the different electrolytic voltages,XRD,SEM,FTIR and Raman were used to investigate the effects on the structure,morphology and properties of GO.The research results showed that when the electrolytic voltage was 1.6 V,the GO with abundant defects,large layer spacing and few layers could be prepared successfully.2. Based on the prepared graphene oxide,we have synthesized the Mo S2/rGO composites by the hydrothermal method.In this paper,the orthogonal experiment of 4factor 4 level was designed.Based on the gas sensing responsiveness of materials to 20 ppm ethanol gas,we have obtained the optimal preparation parameters of Mo S2/rGO composite using the range analysis?reaction temperature=200?,Mo:S=1:5,GO=2 mmol,and reaction time=18 h?.Finally,the structure,morphology and sensor sensitivity of the materials synthesized with the optimal preparation parameters were analyzed by means of XRD,SEM,Raman and other characterization methods.The results show that the Mo S2/rGO composite gas sensor has good gas sensitivity to ethanol gas.In addition,compared with the pure Mo S2,the Mo S2/rGO composite gas sensor has a lower operating temperature,a 3.5 times higher gas sensitivity,a response time of 60 s,a recovery time of21 s,and a good gas sensing stability.3. In order to further improve the gas sensing property of the Mo S2/rGO composites,we combined the Au nanoparticles and Mo S2/rGO materials to synthesize Au-Mo S2/rGO composites using the vacuum ion sputtering apparatus.We have studied the structure,morphology and sensitivity of composites with different sputtering time by means of the XRD and SEM.At the same time,the sensor was tested for the operating temperature,gas responsiveness at different concentrations,response/recovery curve and the cyclic stability.The research results show that compared with Mo S2/rGO,the gas sensing response of the Au-Mo S2/rGO composite was increased by 16% and the gas sensing response time was reduced by 55%.Meantime,the gas sensing sensor shows stable responsiveness after 5cycles.Therefore,the composite Au nanoparticles can effectively improve the gas sensing properties of composites. |
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