Microwave-assistant Hydrothermal Synthesis And Gas Sensor Performance Of Bi₂S₃/MoS₂ Compsite

Gas sensor is a significant part of the sensor field that promotes the development of intelligent sensing and realize the interconnection of everything.Semiconductor gas sensors are extensively implemented considerably in every field.However,many issues need to be worked out and enhanced further,such as high experimental temperature,terrible gas selectivity,and low degree of responses.Therefore,the development work is in a room temperature environment with high selectivity and high responsive gas sensors are particularly important.In this thesis,from the perspective of the development of gas-sensitive sensing materials,a two-step microwave hydrothermal method was used to synthesize a Bi₂S₃/MoS₂ composite material that can be highly selective to NO₂ at room temperature.Firstly,the bismuth nitrate pentahydrate and thiourea were used as raw materials,and the microwave hydrothermal method was also applied to prepare Bi₂S₃ and to improve its preparation process.Selecting the amount of surfactant and the reaction time as the main experimental process variables,a more systematic experimental study was carried out.The microstructure and morphology of the prepared Bi₂S₃ were used as the standard.The SEM and XRD are used to characterize the reactants and the process was advanced by this thesis simultaneously.The conditions of advanced process were that the experimental temperature is200?and the experimental time is 30 mins.Then,with the prepared sea urchin-like Bi₂S₃ as the primary structure,the nano-flower-like MoS₂ was grown secondary by microwave hydrothermal method to form a Bi₂S₃/MoS₂ composite material.Moreover,the gas-sensing properties of the composite material was deeply researched at room temperature.The preparation process of the composite material was advanced by orthogonal and single factor experiment methods,which were based on the gas sensitivity response of the prepared Bi₂S₃/MoS₂ composite material with the NO₂gas 40 ppm.The optimized process parameters:Mo:Bi is 1:22,Mo:S is 1:4,the reaction temperature is 200?,the reaction time is 25 mins,and the precursor p H is 5.According to the morphology,structure,composition,chemical bond,etc.characterization results of the prepared sample's,a two-step growth model was successfully constructed.The results shows that in the process of the composition of Bi₂S₃/MoS₂ composite,the sea urchin-like Bi₂S₃ material was partially decomposed,but the overall sea urchin-like structure is still retained.MoS₂ was directly grown on the sea urchin-like structure of Bi₂S₃.The gas sensitivity test at room temperature can be found that the detection limitation for NO₂ gas was10 ppm,the monitoring range is from10 to 100 ppm,the response is 187%at 40 ppm,and the response/recovery time was 180 s/510 s.Compared with Bi₂S₃,Bi₂S₃/MoS₂ composite gas sensor has the advantages of improved response,response/recovery was shortened time more importantly,it was with good stability and reusability.