Research Of SnO₂ Nanofiber Gas Sensor Prepared By Electrospinning

With the rapid development of society,the problem of air pollution is becoming more and more serious.The demand for high performance gas sensor is becoming more and more urgent,and the material of high performance gas sensor is prepared by the method of electrospinning.In this paper,an interesting phenomenon have been found:The junctions play a positive role on gas sensing of nanofibers.Around this phenomenon we have conducted an in-depth study.The disordered and ordered SnO₂ nanofibers were prepared by far-field and near-field electrospinning respectively.The effects of electrospinning parameters on the morphology of nanofibers were studied.The effect of the junctions in the nanofiber network on the gas sensing performance was studied by controlling the morphology.and the corresponding theoretical analysis was made.The main contents of this paper are as follows:The disordered nanofibers were prepared by far field electrospinning using SnCl₂solution with the addition of polymer as the precursor.The substrate which was used to for the deposition of the nanofibers was the Al₂O₃ ceramic plate with the interdigitated silver electrode.It was found that the polymer species,spray distance,ambient humidity have a greater impact on the morphology of disordered nanofibers.In terms of gas-sensing performance,disordered SnO₂ nanofibers showed the greatest responds at 30℃.By controlling the spinning time,the disordered nanofiber membranes of different thicknesses were prepared.Different with the general films,the thicker the nanofibers membranes were,the higher the response were.Membranes that made up of disordered nanofiber with different diameters were prepared by changing the concentration of precursor.Our test found that the larger the diameter of nanofibers were,the higher the response and the lower the initial resistance was.The ordered nanofibers were prepared by electrospinning using SnC₂O₄ solution with the addition of polymer as the precursor.The substrate was quartz glass printed with interdigitated silver electrodes.The effect of spray distance,moving speed of substrate and precursor viscosity on the morphology of ordered nanofibers was studied.In terms of gas-sensing performance,the ordered nanofibers was similar to the disordered nanofibers,showing the highest response at 30℃too.And the higher the concentration of the precursor was,the higher the response was.The relationship between the response and the concentration of precursor was established.The gas-sensing response of the membrane also became higher with the increased number of the layers.Based on the homogeneous junction model,the relationship between the number of junction and the gas-sensing responses was established.The fitting results are in agreement with the experimental results,and the unique effect of the junctions on the gas-sensing properties of nanofibers is described.