Gas Sensing Research Based On The Tungsten Oxide Hierarchical Structure Materials

Today with the era of progress,rich life and the development of science,people increasingly focus on the environ.ment around security as well as their physical and mental health.Sensing technology,computer technology and communications technology constitute the three backbones of modern science and technology,and the sensing technology provides an important safeguard for accurate information collection of the communication system,information system and automation system.Gas sensor is an important branch of the sensing field,and has wide application in the environmental safety,atmospheric detection,disaster prevention and medical diagnosis,which can effectively monitor all kinds of dangerous gases or hidden safety problems.In the gas sensing field,compared with the traditional ZnO and SnO2 gas-sensing materials,WO3 as a new generation of gas sensitive material,has high sensitivity,good stability and long working life and other advantages,but in order to meet the demand of higher sensitivity and lower working temperature,etc.,we further studied the modified WO3 semiconductor materials in the following three parts.The first part of this paper adopts the hydrothermal method to prepare Co doped WO3 nano-flowers hierarchical structure,and the morphology of materials consists of nanoplates in dozens of nanometers thick to self-assemble into the flower structure.We found the 0.6 at%Co doped WO3 nano-flowers have more superior morphology characteristics and gas sensing properties than other doping amount WO3 nano-flowers.Under the best working temperature of 350?,0.6 at%Co doped WO3 nano-flowers have the highest response to 300 ppm acetone gas(about 151)which is 3.68 times that of pure WO3 nano-flowers with a high selectivity relative to other test gas.The second part of this paper adopts the hydrothermal method to prepare Ag2O3-WO3 microspheres gas sensing material with a hierarchical-structure and the microspheres are 1.6 micrometers in diameter.For 800 ppm ethanol gas selectively,the materials have a response up to 1300 under the best working temperature 487?,and have extremely fast recovery rate.The third part of this paper adopts the hydrothermal method to prepare NiWO4 ternary hollow spheres materials with surface of sea urchins,and the hierarchical structure materials have raised conical spines at external,and internal hollow.The best working temperature is 290?,which is lower than that of pure WO3 microspheres,what is more,they have selectivity to the ethanol gas with a high response(about 112.74).The research in this dissertation is about modification studies based on the WO3 hierarchical structure gas sensing materials,and explored the effect of elements doping,composite nano-heterostructure and new materials in gas sensing procedure.We provided practical experience and theoretical guidance for designing and producing high gas sensing materials in order to realize the application value.