Fabrication Of Micro/nano Structure Based On Metal Oxide Semiconductors And Investigation Of Fast Response Gas Sensing Performance

Nowadays,the production and living standards of human beings are increasing.However,humans are also faced with serious environmental pollution problems,especially atmospheric pollution problems such as severe haze and volatile organic compounds leaked and emitted during chemical production.A gas sensor can quickly,effectively and accurately detect toxic and harmful gases,and it can realize the propose of controlling and preventing the leakage and emission of toxic and harmful gases.Among them,metal oxide semiconductor materials,as an important gas sensing material,have been widely investigated due to high sensitivity,low detection limit,fast response recovery,low cost,simple fabrication,small size,and device integration and miniaturization.Metal Oxide semiconductor sensors have always been the mainstream and research frontier of gas sensors.In order to investigate and fabricate high-performance gas sensors,further reduce the detection limit of the sensor,expand the detection range,increase the reliability and long-term stability of the sensor,the core problem is to synthesize high performance semiconductor oxide gas sensing materials.In this dissertation,we have adopted facile solvothermal methods to synthesize different specific morphologies of metal oxide semiconductor materials for rapid detection of toxic and harmful gases such as volatile organic fatty amines?trimethylamine,triethylamine,and n-butylamine?.The main contents are as follows:1.Three-dimensional hierarchical structure of snowflake?-Fe₂O₃ was designed and synthesized.The snowflake was composed of nano-dendrites with an angle of 60^o between each two bifurcations.According to the nucleation control and diffusion growth mechanism,the growth mechanism of the snow-like morphology was proposed.The as prepared sensor showed ultra-fast response/recovery time?0.9 s/1.5s?at working temperature 260°C,good stability and selectivity to TMA.The gas sensing mechanism were proposed based on adsorption and desorption model,oxygen vacancies,rapid electron exchange within the material,and morphology advantages.2.?-Fe₂O₃ nano-rhombohedral materials were successfully prepared.According to and metastable state growth and Ostwald ripening mechanism,the growth mechanism of the nano-rhombohedron was proposed.The as prepared sensor displayed ultrafast response/recovery time?<1 s/<1 s?for trimethylamine gas at working temperature 240?,good stability and selectivity.The adsorption-desorption model,the internal electronic exchange of materials and the advantage of structural morphology were used to explain such rapid sensing performance.3.V₂O₅ flower-like hierarchical structural materials were syntheized,which exhibited a radial flower morphology composed with nanobelts.Growth mechanism of flower-like morphology was discussed based on mechanism of nucleation control and diffusion control mechanism.The flower-like V₂O₅ hierarchical structure sensor exhibited excellent n-butylamine sensing properties,including fast response/recovery speed of 9 s/49 s,good selectivity,and superior stability.The gas sensing mechanism is proposed based on adsorption and desorption modeling,configuration advantages,and the interaction between the material itself and the detection gas molecules.4.The ZnO-SnO₂ nanoribbon heterojunction materials were designed and prepared,and the triethylamine gas-sensitivity of the ZnO-SnO₂ nanoribbons was tested under laser light irradiation.The growth mechanism of the heterojunction nanoribbons was explained by the theory of crystal nucleus control and the orientation growth mechanism.Under laser irradiation,the sensor exhibited high response 9.9,fast response/recovery time 1.8 s/18 s and low detection limit 1 ppm.Compared with dark condition,the sensing performance was notably improved.The theory of gas sensing was explained based on the light excitation,configuration advantages and heterojunction structure.5.ZnFe₂O₄-ZnO quasi-2D mesoporous heterojunction materials were designed and synthesized.Based on the theory of Gibss-Wulff growth law,multiple nucleation and diffusion control,the growth mechanism of heterojunction was discussed.The prepared ZnFe₂O₄-ZnO quasi two-dimensional mesoporous heterojunction sensor exhibited fast response/recovery 1.9 s/31 s to 50 ppm triethylamine at 240?,as well as low detection limit 0.5 ppm,good selectivity and stability.According to the heterojunction structure,structural morphological advantages and surface charge space charge model,the excellent gas sensing performance mechanism was explained.