Study On Metal Oxide Semiconductor Coaxial Fibers And Their Gas Sensing Performances

Here, we investigate and develop metal oxide semiconductor nanofibers based highperformance gas sensors. Due to poor efficiency of nanoparticles sensing materials,1Dhollow fibers and hollow fibers with different diameters are fabricated by modifiedelectrospinning method to increase the surface areas. Moreover, core-shell heterostructurenanofibers are skillfully constructed by assembling two metal oxide semiconductors toimprove sensing properties via a coaxial electrospinning method. In order to overcomelow sensitivity and poor selectivity of p-type semiconductor, special metal element isloaded onto core-in-hollow-shell NiO micro/nanosphere to obtain high sensitivity andexcellent selectivity. Based on above discussion, five high performances gas sensors arefabricated. The forming process of sensing materials and detailed reason for theimprovement of sensing characteristics are discussed. The main research contents aresummarized as follows:1. SnO2hollow fibers have been successfully fabricated by an efficient and facilecoaxial electrospinning to increase surface areas, which solve poor efficiency issuecaused by the accumulation of nanoparitcles sensing materials. The gas sensor based onthe SnO2hollow fibers and solid fibers are fabricated. And gas sensing results indicatethat SnO2hollow fibers present better ethanol performances in comparison with solidSnO2fibers.2. In2O3micro/nanotubes with different diameters are successfully synthesized by aneffective and template-free coaxial electrospinning method. The gas sensingimprovement effect caused by hollow nanofibers with different diameters is investigatedin detail. And increasing target gas adsorption amount can greatly enhance sensitivity.3. In order to improve low sensitivity and poor selectivity of single semiconductorsensing materials, core-shell structure nanofibers are fabricated and applied to gas sensors. And it can be found that the gas sensing performances are highly dependent on themicrostructure of sensing materials. The α-Fe2O3@NiO and Co3O4/α-Fe2O3core-shellnanofibers are synthesized by utilizing the immiscible characteristics of polymer in theinner and outer fluids. The gas sensing effects of the core and the shell are discussed indetail. And corresponding gas sensing mechanism model is established.4. A facile and efficient electrospinning route is employed to fabricate novel NiO core-in-hollow-shell structured micro/nanospheres. In order to improve the sensitivity andselectivity, Cr-loaded NiO core-in-hollow-shell structured micro/nanospheres withdifferent Cr loading ratios are synthesized. The sensor based on NiO micro/nanosphereswith appropriate Cr loading exhibits high sensitivity and excellent selectivity towardxylene gas, which are very suitable for low concentration xylene gas detection.