Synthesis And Gas/Humidity Sensing Property Of Hydrogen Bond Complex And Amorphous Oxides

With the advancement of technology and the development of industry,the demand for high-performance gas sensor equipment and systems has steadily increased.As the core of gas humidity sensing sensors,it is urgent to develop new sensitive materials with higher quality and accuracy.Considering the characteristics of the sensing material,if there are many active site,the sensing property of the material will be greatly improved.Therefore,a large number of metal active site and O,N,S and other coordination atoms can be used as active site of coordination compounds（complexes for short）materials are expected to become excellent sensitive materials.In addition,compared with traditional metal oxides,amorphous metal oxides have a disordered structure with many dangling bonds,active site and ion channels,which makes them exhibit extraordinary advantages in gas humidity sensors based on surface adsorption.In summary,a new hydrogen bonding complex was synthesized through a simple solvent evaporation method,and then amorphous metal oxides and crystalline/amorphous metal oxides were synthesized through defect control of metal oxides,providing some new ideas for the development of new sensing materials.The main research content includes the following three aspects:（1）A new complex with the chemical formula[Pb（Ka）₂]（denoted as Pb Ka）was successfully synthesized at room temperature.The crystal structure was characterized by single crystal diffraction,XRD and FT-IR.Pb Ka has a double helix spatial structure and a large number of coordinationO atoms as active site.In addition,the intermolecular interactions in Pb Ka crystal stacking were intuitively analyzed through Hirschfeld surface analysis.The Pb Ka humidity sensor has fast response speed and small hysteresis.The sensing mechanism of Pb Ka was analyzed through complex impedance spectroscopy,attributed to the interaction between the surface active layer of Pb Ka and water molecules.（2）Amorphous mesoporous FeO_X nanosheets（denoted as FeO_X-270）and Fe₂O₃-400 were prepared using inorganic salt NaNO₃ as a template and Fe（acac）₃ as a precursor by adjusting the calcination temperature.Compared with Fe₂O₃-400,FeO_X-270 has the highest sensitivity,smaller hysteresis,and excellent repeatability.Due to its excellent humidity sensitivity,FeO_X-270 has shown great potential in monitoring human respiration（respiratory detection）and human skin moisture evaporation（finger detection）.The main reason why amorphous nanosheets exhibit excellent humidity sensitivity is that FeO_X-270 has larger specific surface area and more active site.（3）Using templates to control the growth direction of SnO₂,CuO,amorphous SnO₂,and CuO modified amorphous SnO₂ materials（CuO/SnO₂）were prepared by regulating the degree of ion exchange between Cu ions and Sn ions,as well as controlling the calcination temperature.As a humidity material,CuO/SnO₂ has higher response values,shorter recovery time and smaller hysteresis compared to SnO₂.The excellent humidity sensing performance is attributed to the rich defects brought about by p-n heterostructures.In addition,the study explored the response of the sensor to dimethylamine（DMA）gas and found that the sensor had a good response to DMA under lower humidity and room temperature conditions.This work provides new materials for high-performance sensors related to humidity detection through the formation of amorphous metal oxides with heterojunctions.