Research On The Sensitization Performance Of Gas Sensors Base On Graphene Modified Fe₂O₃ And WO₃

With the advent of the 5G era,the Internet of Things has become possible.As a medium for acquiring information,sensors can rapidly transfer the captured information.As people’s requirements for the quality of the living environment increase,the detection and monitoring of the gas environment is very important.Gas sensors have a wide range of applications in chemical pollution,public safety,indoor poisonous gas detection,disease diagnosis and agricultural environment monitoring.The gas sensor based on semiconductor oxide has attracted the attention of the industry due to its low cost,simple process and good portability.Graphene has excellent electrical properties.The reduced graphene oxide（r GO）obtained after reduction and oxidation can deduce the working temperature of the gas sensor,increase its sensitivity,and greatly optimize the performance of the device after being compounded with the semiconductor oxide.In this paper,two typical gas-sensing materials r GO-Fe₂O₃ and r GO-WO₃ were synthesized,and the preparation of two high-performance,low-power acetone and H₂S sensors was realized.The experiment contents are as follows:1.The Fe₂O₃ nanoparticle sensitive material modified by reduced graphene oxide（r GO）was prepared by one-step hydrothermal method.XRD,SEM,TEM,Raman,XPS,BET and other characterization methods are used to analyze the microscopic morphology and chemical composition of the material.A serious of semiconductor gas sensors were fabricated.Based on the gas sensitivity characteristics,it was found that the 0.25 wt%r GO-Fe₂O₃ gas sensor had the highest sensitivity to acetone gas.The response of the sensor to 100 ppm acetone at 200°C was about 11,and the response time is only 5s.The Fe₂O₃ gas sensor had good instinct characteristics for acetone,and r GO provided more defects and active sites for the adsorption of acetone molecules.At the same time,the heterojunction formed by P-type r GO and N-type Fe₂O₃ expanded the depletion layer and barrier,further improved the gas sensitivity of the device.Therefore,the excellent gas sensitivity of the 0.25 wt%r GO-Fe₂O₃gas sensor can be attributed to the synergistic effect of r GO and Fe₂O₃.2.The reduced graphene oxide modified flake WO₃ materials were prepared by step-by-step reaction.Firstly,flake WO₃was synthesized by first hydrothermal and then acidified,then fully mixed with graphene oxide,and its microscopic morphology and chemical composition were analyzed.The gas-sensitivity analysis of the prepared material showed that the hybrids had optimized the optimal working temperature and sensitivity compared with pure flake WO₃.The response of the 2 wt%r GO-WO₃ gas sensor to 10ppm H₂S at 175°C can reach 11.03,which was 3.75 times that of the base Fe₂O₃ gas sensor,and the response time was only 3 s.The detection limit was reduced from 2 ppm to 500 ppb.We attributed the improvement of the H₂S sensitivity of the hybrids to the large number of defects introduced by r GO decorations and the heterointerfaces formed between r GO and WO₃.Through the performance comparison of the above two gas sensors,considering that graphene itself has almost no response to acetone and H₂S,its sensitization performance is completely derived by the modified interface.The graphene modified heterointerfaces add a large number of interface active sites,which also brings a wider electron depletion layer and a higher interface barrier.Therefore,the graphene interface sensitization is essentially the result of the synergy of the two sensitization mechanisms,chemical and electronic.Moreover,the interface sensitization effect of graphene is directly related to the proportion of interface active sites.By rationally designing r GO-SMOs sensitive materials to construct large-area hetero structures,and making full use of the interface sensitization effect,it is expected that gas sensors with better performance can be developed.