Study On Synthesis And Gas Sensing Properties Of Novel Structure Metal Oxide

The environmental pollution problems is becoming increasingly prominent today.It is urgent to monitor various toxic and harmful gases in environment.Hence,the research and development of gas sensor is a critical project.Advanced sensing materials and device technologies are essential of the gas sensor research,and has important scientific significance and application value for the research of novel and highly sensing performance gas sensors.Metal oxide semiconductor materials,have excellently applicative value in gas sensor field owing to high sensitivity,facile structure,low cost and easy to be integrated.It is expected to enhance sensing performance of gas sensors by designing micro-structure of sensing materials,hybridizing the materials with different physical and chemical properties,and research its effect on gas sensing performance.In this paper,we focus on novel micro-structure of MoO3 and Fe₂O₃ to improve the sensing performance of gas sensors.The main contents are as follows:（1）We reported a facile,environmentally friendly,in-situ growth and economic thermal oxidization method for growing large area,flexible and aligned a-MoO3 microsheets arrays（MMAs）on Mo foil.The aligned a-MoO3 microsheets arrays have a preferential（10 0）orientation of crystallities.Additionally,this kind of MMAs demonstrates excellent flexibility.Sensor Based on MMAs hardly showed gas sensing performance under current experimental conditions,while exhibited excellent temperature sensing properties.（2）We fabricated self-assembly biomimetic fern leaf-like α-Fe₂O₃ and research the sensing properties.The XRD analysis demonstrated that the sample that we made were a-Fe₂O₃,no impurities were detected.The SEM and TEM images showed the morphology of the sample is highly similar to natural fern leaf,and angle between branch and main stem was measured to be about 64°.The as-prepared fern leaf-like a-Fe₂O₃ was used as sensing materials for gas sensors.The result showed that sensitivity to 100 ppm 1-butanol gas is 8.26,and quick response（recovery）time to 1-butanol gas at 10 ppm,20 ppm,50 ppm and 100 ppm was 17.5 s（9 s）,24 s（16 s）,26 s（18 s）and 34 s（21 s）,respectively.Moreover,sensor based on fern leaf-likea-Fe₂O₃ showed wonderful selectivity and long-term stability.Compare to a-Fe₂O₃ nanoparticles,this kind of gas sensor showed higher sensitivity and quicker response/recovery speed.（3）We synthesized fern leaf-like a-Fe₂O₃/SnO2 heterojunction structure by two-step hydrothermal reaction.The XRD analysis demonstrated that the sample that we made were a-Fe₂O₃ and SnO2,no impurities were detected.The as-prepared fern leaf-like a-Fe₂O₃/SiO2 heterojunction was used as sensing materials for gas sensors.The result indicated that the response to 1-butanol gas at 10 ppm,20 ppm,50 ppm and 100 ppm was 5.41,9.29,15.01 and 22.73,respectively.These results indicated that the a-Fe₂O₃/SnO2 sensor displayed about two fold enhancement in sensitivity compared to the pure a-Fe₂O₃.Moreover,this gas sensor exhibited good selectivity and long-term stability,and the optimized work temperature drop to 200℃.