Construction Of Three-dimensional FeYO₃,WO₃,Bi₂WO₆ And Study On Their Gas Performance

On the one hand,with the rapid development of industry,the consumption of fossil fuels continues to grow,and many toxic and harmful volatile organic compounds(VOCs)are produced.The resulting haze weather,greenhouse effect,ozone depletion and other problems have become increasingly serious.Moreover,the efficient and accurate detection of the toxic,flammable and explosive gases has been caught great attention.Therefore,there is an urgent need to prepare novel gas sensors.On the other hand,the sensing performance of gas sensor is closely related to the morphology,size and dispersibility of nanomaterials,especially three dimensional(3D)structural materials.Because 3D structure can provide highly effective specific surface area,it has attracted widespread attention.Therefore,we have improved the morphology and structure of the existing materials by designing experiments to optimize their gas sensing properties,and then compared the differences in gas sensing performance of the same materials with different morphologies prepared by different methods.The formation mechanism and gas sensing mechanism were also analyzed.The main research work is as follows:1.The perovskite Iron Yttrium Oxide(FeYO₃)microspheres on the basis of bio-templates with orange peels have been successfully obtained by a facile hydrothermal‘green synthesis'along with multifarious characterization techniques.The XRD demonstrated that the synthesized sample was single phase FeYO₃ with a hexagonal perovskite structure.Moreover,the solid microspheres with relatively rough surfaces were displayed by SEM and TEM.Benefiting from this fact,the sensor based on p-type semiconductor FeYO₃ microspheres showed good gas sensing characteristics towards ethanol at the optimum operating temperature of 330?with a low detection limit(1ppm),good repeatability and fast response/recovery time(30 s/56 s),etc.Accordingly,this work supplies a good experimental basis for FeYO₃ as a novel semiconductor gas sensing material soon.2.To further optimize the gas sensing properties of the synthesized WO₃ materials,the popcorn-shaped WO₃ microspheres assisted by yeast cells were successfully prepared by a one-step hydrothermal method.The structure and morphology were measured by multifarious characterization techniques including XRD,SEM,TEM and BET.The results displayed that compared with WO₃,the yeast@WO₃ possesses unique popcorn-shaped structure and the pore size is significantly increased(40.0052 nm,52.4031 nm),which has a great effect on the improvement of gas sensing performance.The survey results about gas sensing performance of two sensors showed that the yeast@WO₃ sample was so sensitive to ethanolamine among various VOCs at 180?.Besides,the sensor based on the proposed yeast@WO₃ microspheres showed higher response value,shorter response/recovery time,etc.The optimization of these gas-sensing properties for WO₃benefits from the improvement of morphology and structure.Therefore,the popcorn-shaped yeast@WO₃microspheres material is identified as an efficient and promising ethanolamine gas sensor in the future.Meanwhile,the formation mechanism of popcorn-like structure and related gas sensing mechanism were analyzed.3.To further optimize the gas sensing performance of the reported perovskite Bi₂WO₆,the dandelion-like Bi₂WO₆ nanostructures were successfully prepared by a one-step hydrothermal method and necessary adjustment to the amount of ethanol,acetic acid,deionized water and CTAB.And the morphology of the synthesized Bi₂WO₆ was improved.The XRD,SEM,TEM and BET test were employed to characterize structure and morphology of 3D Bi₂WO₆ dandelion.The sample was made into a gas sensor which exhibited unique good ethylene glycol sensing properties at a lower optimum operating temperature of 270?,i.e.,high response value,excellent repeatability,a detection minimum limit of 1 ppm and so forth.Hence the novel 3D Bi₂WO₆ dandelion could be an ultra-sensitive ethylene glycol candidate semiconductor material.