Synthesis And Gas-Sensing Properties Of Indium-based Metal Organic Framework Derivatives For N-butanol Detection

With the rapid development of industry,more and more toxic and harmful substances were exhausted into our surrounding environment,which causes various serious air pollutants.Moreover,different kinds of accidents,such as diseases,explosions and fires,will happen because of the emission of toxic,harmful and flammable and explosive gases.The serious air pollution will not only seriously threatens human health and safety,but also hinders social progress and development.With the increasing of environmental protection and health awareness,great attention has been focused on the detection of various pollutants in our environment.Recently,numerous of high sensitive sensing devices have been explored to detect the harmful and explosive gases.Gas sensors have attracted great attention because of the advantages of high sensitivity,small size,low power consumption and simple process,which has been widely used in different fields of gas detection.In this thesis,the indium-based metal organic framework（In-MIL-68）was prepared by solvothermal method,and the gas sensing material of In-MIL-68 derivative was obtained by annealing process.Meanwhile,the pure and Au modification In-Zn metal organic framework derivatives were prepared by loading Zn and Au elements.Meanwhile,the morphological structure,crystal structure and element composition of as-synthesized samples were characterized through SEM,XRD,EDS methods.The gas sensing properties were conducted on the as-fabricated gas sensors toward n-butanol detection.The experimental results of this thesis are as follows:（1）The indium-based metal organic framework（In-MIL-68）was prepared by solvothermal method.The morphology of In-MIL-68exhibits a solid hexagonal prism structure with a length of about 8μm and a diameter of about 2μm.Furthermore,the obtained In-MIL-68derivative displays a hollow and porous hexagonal tubular structure by annealing.After growth Zn-based nanostructures using hydrothermal method,the Zn-based In-MIL-68 derivative displayed the hollow microtube structure wrapped by a nano-hybrid sheet.Moreover,the growth of the nano-hybrid sheet causes the microtube size to increase slightly.Meanwhile,the gas sensing experiment were conducted on the as-fabricated In₂O₃ sensor,and the response can reach to 196.2 toward100 ppm n-butanol under the optimal operating temperature of 230℃.While,the Zn modification In-MIL-68 gas sensor can reach to 280.3under optimal operating temperature of 290℃,which indicates that the introduce of Zn element can effectively enhance the gas sensing performance of In-MIL-68 derivative structure.（2）The different concentration of Au loading Zn-based In-Zn metal organic framework derivatives sensing material were prepared with Au loading of 0.5 mol%,1 mol%,3 mol%,and 5 mol%.The SEM images showed that the loading of Au has no apparent affect of the morphology and structure.The gas sensing experiments reveal that introduce of Au not only decreased the working temperature of Au/In-Zn to 140℃,but also greatly improved the response.Moreover,the as-fabricated A₁In Zn sensor exhibits the highest response about 1610 toward 100 ppm n-butanol.As results,the gas sensing properties of In-MIL-68 derivative sensor can be significant improved by the introducing of Zn and Au elements toward n-butanol.For the Zn-based In-MIL-68 derivative sensor,the enhanced gas sensing properties can be ascribed to the increasing activity of oxygen adsorption sites of In₂O₃,causing the enhancement of the specific surface area.Meanwhile,the formation of n-n heterojunction,which also promotes the gas-sensing reaction.Moreover,for the Au loading Zn-based In-MIL-68 derivative sensor,the adsorption and desorption between the sensitive material and gas molecules can be greatly improved because of the increasing active sites on the surface of the sensing material,which is favor for the reaction of gas molecules and sensitive material.