Performance Modeling And Experimental Study Of SnO₂ Nanowire Gas Sensor Based On Electrospinning Technology

Semiconductor metal oxide thin film materials have always been the focus of high-performance gas sensors.Electrospinning technology provides a simple and universal way to produce thin-film structures with highly porous fiber morphology.The disordered fiber film based on far-field electrospinning is easily influenced due to the film cracking.The ordered fiber array prepared by near-field electrospinning can effectively avoid cracking and expand the application of fiber materials in patterned or flexible devices.However,the performance will be limited due to the decrease in the number and aspect ratio of fibers.In this paper,the gas sensing response characteristics of SnO₂ fiber film will be studied through theoretical modeling and experiments,and other types of thin film structures were prepared for comparison and verification.In addition,an ordered array of SnO₂/Ti O₂ composite fiber was prepared to improve the gas-sensitive performance by synergistic effects.The specific research content is as follows:Firstly,based on the nanowire conductance model and gas diffusion theory,the diffusion process of the target gas in the fiber film during gas-sensitive response was analyzed and calculated.Aiming at the film cracking phenomenon,a gas sensing model under actual conditions was established in different stages,and the theoretical curve of the gas-sensitive response of the fiber film was derived.Secondly,nanofiber films and traditional particle-stacked films were prepared by electrospinning method and sol-gel method.The change of gas response with film thickness and the relationship between film cracking degree and thickness were analyzed through film morphology change and performance test,which are consistent with the derived theoretical gas response curves.It was found that the correlation between the response S and the thickness L is an inverted V shape.For fiber films,fiber breakage caused by film cracking impedes carrier transport and reduces gas-sensing performance.For dense films,the cracking of the film within a certain range which is conducive to the diffusion and adsorption of the gas can effectively improve the gas-sensitive response.Finally,the controlled depositions of SnO₂/TiO₂ composite fibers were achieved by near-field spinning.The morphology,structure and gas sensing performance of SnO₂/Ti O₂ laminated fiber and SnO₂/Ti O₂ mixed fiber were compared by experiments.Studies have shown that the gas sensitivity performance of the two types of SnO₂/Ti O₂ composite fibers are enhanced by the formation of heterojunctions,compared with pure SnO₂ fibers.However,for the same 20-layer composite fiber,the gas-sensitive response of the laminated fiber has increased by 2.6 times while the mixed fiber has only increased by 1.4 times.It can be attributed to the fact that particle agglomeration is more likely to occur in mixed fibers,resulting in an inconspicuous heterogeneous interface.