Design And Performance Research Of Volatile Organic Compound Gas-sensitive Materials

With the development of science and technology and the progress of society,gas sensors with high performances have been widely used in air quality detection,industrial production safety and non-invasive disease diagnosis.Gas sensors based on metal oxide semiconductor（MOS）have became a hot topic in the field of gas sensors due to its advantages of low cost,easy fabricate and excellent gas sensing properties.Sensing materials are the core of gas sensors.The research on sensing materials with high performances is one of the main measures to improve the sensitivity of gas sensors.In this dissertation,a variety of MOSs materials with unique morphology and excellent gas sensing properties were synthesized by several simple methods,and the surface decoration of the as-synthesized materials was performed to optimize the gas sensing properties.The main results are as follows:（1）Gas sensing materials with various morphologies were synthesized by a simple hydrothermal method,including W₁₈O₄₉ nanowires,W₁₈O₄₉ hollow nanospheres,SnO₂nanospheres and ZnO nanorods.Their good morphology and unique structure make them have large specific surface area and high electron mobility,which makes them show good selectivity to volatile organic compounds such as triethylamine,acetone and n-butanol.Porous SnO₂ films were prepared by sacrificial template method to detect TEA at room temperature.Ultra-thin SnO₂ films were prepared by atomic layer deposition.The excellent surface uniformity made them exhibit excellent gas-sensitive stability.（2）In combination with in-situ redox and atomic layer deposition techniques,single or multi-noble metal nanoparticles were successfully loaded on the surface of MOS,and the heterogeneous structure of noble metal-MOS was constructed,including Ag/Pt/W₁₈O₄₉nanowires,Au/Co₃O₄/W₁₈O₄₉ hollow nanospheres,W₁₈O₄₉/Pt hollow nanospheres and single atom Pt modified SnO₂ film.It is found that the presence of electronic effects and catalytic spillovers of noble metals can enhance the surface activity of sensing materials,promote the surface gas reaction,and improve the sensitivity,response-recovery speed and selectivity.At the same time,the influence of noble metal content on gas sensitivity was also studied.（3）MOS-MOS composite structures were designed and prepared by using two-step hydrothermal method or atomic layer deposition technology,including W₁₈O₄₉/Fe₂O₃hollow nanospheres,SnO₂/Co₃O₄ nanospheres and TiO₂@ZnO core-shell nanorods,and the high-performance detection of acetone and n-butanol was realized.It is found that the synergistic sensitization effect between different components can improve the gas-sensitive properties of gas-sensitive materials.At the same time,the influence of load content on gas sensing properties was studied,and the results showed that a certain amount of decoration was helpful to improve gas sensitivity,but too much decoration would produce inhibition effect.Through the above three parts of work,this dissertation systematically studied the influence of noble metal decoration and heterogeneous structure on gas sensing properties.This dissertation carried out not only offers a new thought for constructing new gas sensor,but also in the deep understanding of the basic research level,the relationship between the structure,composition and properties of clear enhancement mechanism of micro-nano structure,enrich the sensitive mechanism of gas sensor based on MOS for sensor research provides a new theory,new method and new technology.