Performance Research Of Gas Sensor Based On MoSe₂ Composite Heterostructure

Nowadays,with the rapid development of science and technology,there are still harmful gases that endanger human life and safety,and it is still a challenge to develop and design high-performance sensor materials for monitoring and detecting these harmful gases in the field of gas sensing.Because of its large specific surface area and high conductivity,two-dimensional transition metal materials have good physical and chemical properties,which has become a hot spot in gas sensing research recently.Moreover,it is a feasible scheme to combine different semiconductor materials to form a composite material with heterostructure to improve the gas sensing performance of the material.Composite materials with heterostructure can promote charge separation and transfer,increase specific surface area,reduce crystal plane barrier,and have more adsorbable active sites when exposed to gas,which is widely used in the field of gas sensing.This paper mainly focuses on the preparation of composite materials based on different heterostructures of MoSe₂,characterized the morphology,structure and gas sensing properties of the materials,and explored its possible sensing mechanism.The main work is as follows:（1）Cu₂O nanoparticles were prepared by reducing copper chloride dihydrate with ascorbic acid,and MoSe₂nanosheets were compounded with Cu₂O nanoparticles to form composite material with P-P heterojunctions structure.The morphology,structure and gas sensing properties of the material were characterized.The results show that this composite material has higher sensitivity to NH₃,and Cu₂O/MoSe₂-2 sample has the best gas sensitivity.（2）CdS/MoSe₂nanocomposites with P-N heterojunction were prepared by two-step hydrothermal synthesis.The materials were characterized by SEM,TEM and XRD,and the sensing properties were also tested.Through the comparison of gas sensitivity parameters,the CdS/MoSe₂-5 sample showed the highest sensitivity.（3）MoSe₂nanosheets were synthesized by solvothermal method and modified by TiO₂QDs,which formed composite material with P-N heterojunctions structure.This structure can effectively promote the separation and transfer of charge,and enhance the room temperature sensitivity of the material to NO₂under the excitation of UV light.The morphology,structure and conductivity of the sensitive materials were characterized by scanning electron microscope,transmission electron microscope,X-ray diffraction and photoluminescence spectrum,and the possible sensitive mechanism was explored.