Preparation And Performance Of Sensing Materials For Detecting Hydrogen And Acetone Gas

As a gas detection device,the gas sensor has important application value in the fields of industrial exhaust emission monitoring,fuel emission monitoring,automobile exhaust emission monitoring,household safety,and environmental pollution monitoring.Metal-oxide-semiconductor（MOSs）-based gas sensors have received extensive attention from researchers because of their simple manufacturing process,low cost,and excellent performance.In this paper,two kinds of metal oxide semiconductors（WO₃ and ZnO）were studied,and high-performance hydrogen sensors and acetone gas sensors were successfully prepared.In the experiment,the microstructure of WO₃ and ZnO nanomaterials with high specific surface area was prepared as the starting point,and their gas sensitivity was enhanced by loading PdO and Rh₂O₃ on the surface of WO₃ and ZnO,respectively.The crystal structure,elemental composition,chemical valence state,surface morphology,heterojunction interface,specific surface area and pore structure of heterojunction gas sensing materials were characterized by XRD,XPS,SEM,TEM and N₂ adsorption/desorption.In addition,in order to further study the reasons for the improvement of gas sensitivity of materials,we also carried out the first-principles calculation and analysis of materials.The main research work of this paper is as follows:（1）Quasi-one-dimensional WO₃ nanospindles were synthesized by hydrothermal method.PdO nanoparticles with different proportions were successfully loaded onto the WO₃ surface by impregnation and calcination,and the p-PdO-n-WO₃ heterostructure was successfully constructed.When the atomic ratio of Pd and W in the composite is 3 at%,the gas sensing performance of the sensor is the best.At the optimal working temperature of 150°C,the detection limit of hydrogen is very low as 1 ppm,and the response time is9 s.The response value of hydrogen to 50 ppm concentration is 76,and the response time is only 1 s.This sensor has excellent stability.Such excellent gas sensitivity makes it have broad application prospects in the safe storage of hydrogen and leak detection.（2）Basic zinc carbonate（Zn₄CO₃（OH）₆·H₂O）was successfully synthesized by hydrothermal method,and porous layered ZnO was successfully prepared by calcination of basic zinc carbonate（Zn₄CO₃（OH）₆·H₂O）.Finally,different proportions of Rh₂O₃nanoparticles were successfully loaded onto the surface of porous ZnO to obtain p-Rh₂O₃-n-ZnO heterostructures by impregnation and calcination.The results shows that when the composite mass ratio of Rh Cl₃·3H₂O and ZnO was 1:16,the prepared sensor had the best gas sensing performance for acetone,with a detection limit of 50 ppb and a response time of only 8 s.This gas sensor shows good linearity for acetone at different concentrations,and also shows good linearity for acetone at different humidity,which has great potential for application in the diagnosis and detection of diabetic patients.