Preparation And Gas Sensing Properties Of Ti₃C₂T_x-MFe₂O₄(M=Zn,Mg,Ca,Ni) Composite Materials

The introduction of the first chapter gives a brief overview of the research background and practical significance of the research,and briefly describes the classification,sensitive principles,performance indicators and performance improvement methods of gas sensors.The gas sensing materials involved in this paper are briefly introduced.Ti₃C₂T_x is a new type of graphene-like two-dimensional material with excellent electrochemical and catalytic properties which has been applied in the fields of photocatalysis and electrochemistry.Spinel-type oxide AB₂O₄has stable properties and high catalytic activity,and has usually been a commonly used gas sensing substrate material.In Chapter 2,Zn Fe₂O₄ nanomaterials were prepared by hydrothermal method,Ti₃C₂T_x was prepared by etching Ti₃Al C₂ with concentrated hydrochloric acid and ammonium fluoride.And Ti₃C₂T_x-Zn Fe₂O₄ composite materials were prepared by ultrasonic mixing and dispersion method.The gas sensitivity measurement results showed that the 10wt%Ti₃C₂T_x-Zn Fe₂O₄ composite material had good acetone gas sensitivity of 28.7 to 100 ppm of acetone vapor at room temperature,and the response and recovery time were only 600.9 s and 376.5 s,respectively.The lowest detection limit concentration was as low as 1 ppm.In Chapter 3,the Mg Fe₂O₄ nanomaterials were prepared by the sol-gel method,and a series of Ti₃C₂T_x-Mg Fe₂O₄ composite materials were prepared by the ultrasonic mixing and dispersion method.The gas sensitivity test results showed that the 2.5wt%Ti₃C₂T_x-Mg Fe₂O₄ composite material had a sensitivity of 4.7 to 100 ppm ammonia at room temperature.The gas sensing selectivity of S_{100 ppm ammonia}/S_{100 ppm paraxylene}=1.9,the minimum detection limit of ammonia concentration could reach 0.5 ppm,and the response and recovery time were only 10.8 s and 6.6 s,respectively.In Chapter 4,Ca Fe₂O₄ was prepared by sol-gel method,and Ti₃C₂T_x-Ca Fe₂O₄composite was prepared by ultrasonic dispersion and mixing method.The gas sensing measurement results showed that the sensitivity of 9wt%Ti₃C₂T_x-Ca Fe₂O₄ composite to 100 ppm formaldehyde at 230^oC was 4.33,and the minimum detection limit of 9wt%Ti₃C₂T_x-Ca Fe₂O₄ composite to formaldehyde was as low as 0.1 ppm and the response and recovery time were only 27.2 s and 7.8 s.In Chapter 5,Ni Fe₂O₄ was prepared by hydrothermal method,and a series of Ti₃C₂T_x-Ni Fe₂O₄ composite materials were synthesized by ultrasonic mixing and dispersion method.The gas sensing measurement results showed that the 3wt%Ti₃C₂T_x-Ni Fe₂O₄ composite material had better acetic acid gas sensitivity.The sensitivity to 100 ppm acetic acid could reach 17.65 at an operating temperature of230^oC,and the gas sensing selectivity of S_{100 ppm acetic acid}/S_{100 ppm ethanol}=5.58.The minimum detection limit for acetic acid was as low as 0.05 ppm with a sensitivity of1.17,and the recovery time was only 6.3 s.