The Design,Preparation And Sensitivity Research Of Acetone Sensor

Acetone,as a common volatile organic compound,is a slightly hazardous pollutant.It is of great significance for industrial production,animal husbandry and medical testing to develop an acetone sensor with high sensitivity,low detection limit,which could work at room temperature.In this dissertation,quartz crystal mircobalance?QCM?and plane interdigitated electrodes were chosen as sensing structure.QCM acetone sensors were developed based on poly?ethyleneimine??PEI?,and the UV-enhanced resistance-type acetone snesors were developed based on Pd@PdO@ZnO.The sensitive films were characterized and the gas sensing properties of sensors at room temperature were systematically studied.The main research work include the following two aspects:The QCM sensor was studied to detect acetone.PEI and amido-graphene oxide?GO-NH₂?were selected as sensitive material and deposited on the QCM devices by facile spray method and drop coating method to develop single layer flim of PEI and layered film of PEI and GO-NH₂?PEI/GO-NH₂?.The features of single layer film and layered film were characterized by morphology analysis?SEM?and spectral analysis?XPS and UV-Vis spectra?.It was observed from the results of SEM that the layered film has obvious folds because of the presence of GO-NH₂,which increases the specific surface area of the material and is favorable for the adsorption of acetone molecules.The results of XPS confirmed the hydrogen bonding between PEI and GO-NH₂.It was confirmed based on UV-Vis spectrum analysis that acetone has nucleophilic addition reaction with the amine functional group in PEI and GO-NH₂,which results in the red shift of the absorption peak.The gas sensing properties of PEI and PEI/GO-NH₂ QCM sensor were researched and compared with each other at room temperature.The results showed both sensors have good response-recovery performance in the range of 2-10ppm acetone,and also have good repeatability and selectivity.The performance of the QCM acetone sensor with PEI/GO-NH₂ layered film is better than that of the QCM acetone sensor with a single layer of PEI film.The QCM sensor with PEI/GO-NH₂layered film was chosen as an optimized sensor and its stability was tested.The results showed that the QCM acetone sensor with PEI/GO-NH₂ layered film has good stability.The gas sensing mechanism of the QCM acetone sensor for single-layer PEI film and PEI/GO-NH₂ layered film was analyzed in combination with characterization and gas sensitivity test results.It was considered that the nucleophilic addition reaction between acetone molecule and the amine functional group in PEI and GO-NH₂ promotes sensor response to acetone.Finally,the relevant gas-sensing mechanism model of QCM acetone sensor based on PEI was established.The UV-enhanced resistance-type acetone snesors based on Pd@PdO@ZnO were studied.The sensitive material was prepared by sol-gel method and characterized by morphology analysis?SEM and TEM?and spectral analysis?XRD,XPS and UV-Vis spectra?.The formation of Pd@PdO@ZnO nanoparticles can be obviously observed in the results of SEM and TEM.The results of XRD and XPS further confirmed the existence of Pd,PdO and ZnO.The absorption band edge and a characteristic absorption peak can be observed from the results of UV-Vis.The forbidden band width of the composite material is 3.11eV by calculation.The sensor was fabricated by spin-coating and the response of the sensor to acetone was tested under ultraviolet light at room temperature.The results showed sensor has good response-recovery performance in the range of 10-50 ppm acetone,and also has good repeatability and selectivity.The gas sensing mechanism of the UV-enhanced resistance-type acetone snesors based on Pd@PdO@ZnO was analyzed in combination with characterization and gas sensitivity test results.It is considered that the photogenerated electron hole pairs generated in the material under ultraviolet light conditions,the PN junction formed by ZnO and PdO and the catalytic effect of noble metal Pd makes the sensor exhibit response to acetone at room temperature.Finally,the relevant gas-sensing mechanism model the UV-enhanced resistance-type acetone snesors based on Pd@PdO@ZnO was established.