Preparation And Gas Sensing Properties Of Two-dimensional Materials-NiFe₂O₄ Composites

This paper discussed the gas sensing materials and modified the Ni Fe₂O₄composite metal oxide.The specific contents are as follows:In the first chapter,it mainly introduced the development and classification of gas sensors,the working principle,performance indicators and the methods to improve the gas sensing performance of semiconductors,the structure,preparation methods and application of spinel composite oxides,the structure and characteristics of grphene,g-C₃N₄,Mo S₂and WS₂were also briefly explained.In the second chapter,Graphene-Ni Fe₂O₄composites were prepared via hydrothermal method(180 ?,12 h),and their gas sensing properties were studied.The Graphene-Ni Fe₂O₄composites were characterized by XRD,Raman and XPS etc,the results show that only graphene and Ni Fe₂O₄exist in the composites.the sensitivity of 1.5 wt%G-Ni Fe₂O₄composite to 100 ppm ammonia at room temperature was up to 11.4,and response/recovery time were 36 s and 16 s,respectively,the detection limit was 0.01 ppm.In the third chapter,g-C₃N₄-Ni Fe₂O₄composites with different amount of g-C₃N₄dispersion were prepared via hydrothermal method(180 ?,12 h),and their gas sensing properties were studied.The micro-morphology of composites were characterized by SEM,TEM and HRTEM,the results showed that Ni Fe₂O₄was combined with g-C₃N₄.The sensitivity of composite with 5 m L g-C₃N₄dispersion to100 ppm acetone was 9.8 at the operating temperature of 200?,and the response/recovery time were 4 s and 11 s,respectively,detection limit was 0.1 ppm.In the fourth chapter,Mo S₂-Ni Fe₂O₄composites were prepared via hydrothermal method(180?,12 h),and their gas sensing properties were studied.The Mo S₂-Ni Fe₂O₄composites were characterized by XRD,SEM,TEM,HRTM,EDS and XPS.The results showed that the composites consisted of Mo S₂and Ni Fe₂O₄.The gas-sensitivity performance results show that when the composite with 5 m L Mo S₂dispersion,the sensitivity of 5 m L Mo S₂-Ni Fe₂O₄composite to 100 ppm acetaldehyde was 39.5 at room temperature,and the response/recovery time were 150s and 30 s,respectively,detection limit was 1 ppm.In the fifth chapter,Ni Fe₂O₄doping with different amount of WS₂dispersion were prepared via hydrothermal method(180 ?,12 h),and their gas sensing properties were studied.The WS₂-Ni Fe₂O₄composites were characterized by XRD,SEM,TEM,HRTM,EDS and XPS.The results showed that the composites consisted of WS₂and Ni Fe₂O₄.The gas-sensitivity performance results show that when the composite with 3 m L WS₂dispersion,the sensitivity of 3 m L WS₂-Ni Fe₂O₄composite to 50 ppm ammonia was up to 195.0 at room temperature,the response/recovery time were 63 s and 19 s,respectively,and detection limit was 0.01 ppm.