Study On High Performance Crystal Facets Regulation And Gas Sensing Properties Of Metal Oxide Semiconductors

Human beings cannot live without air,and air quality has a profound impact on the quality of human life.With the acceleration of industrial modernization,air pollution is becoming more and more serious.Some compounds containing carbon,nitrogen and sulfur in the industrial exhaust gas will stimulate the respiratory tract and cause respiratory discomfort.On the other hand,indoor pollutants also affect people's physical health.VOCs gases produced by decoration or furniture will stimulate people's eyes,respiratory tract,skin,etc.,and there is also the risk of cancer.Therefore,the development of efficient gas sensors plays an important role in helping humans protect the environment and avoid risks.Among them,metal oxide semiconductor gas sensor is the research hotspot.In the process of research,it is found that the specific surface area and morphology have important effects on the gas-sensitive properties of metal oxide semiconductor materials.The sensitive material with large specific surface area has more active sites,which is helpful to improve the sensitivity of the sensor.The proper morphology also plays a role in reducing agglomeration and accelerating electron transmission.At the same time,some research results show that,for the same metal oxides,the morphology with a small specific area performs better than that with a large specific surface area.This may be caused by the differences in the exposed crystal facets of materials with different morphologies and the different gas-sensitive properties of different crystal surfaces.In this thesis,we try to construct some special crystal surfaces on the surface of the sensitive body and find out the intrinsic relationship between the surface morphology and the gas sensing performance.The main work is as follows:(1)By adjusting the pH of the precursor solution,the ZnO material with six-edge disk morphology and six-prism morphology were synthesized by hydrothermal method.The gas-sensitive element was fabricated and measured.HRTEM and SAED characterization results showed that the base sufaces were {0001} crystal facets,and the side sufaces were {10(?)0} crystal facets.The test results showed that the six-edge disk was more sensitive to ethanol and acetone than the six-prism,and the six-edge disk had a faster response and recovery rate to acetone.(2)Porous NiO nanopsheets were synthesized by hydrothermal method and carried out with different proportions of Pt loading.The gas-sensitive properties were measured.XRD characterization showed that NiO was Na Cl structure.Through HRTEM and SAED characterization analysis,it is believed that the material was single crystal and the exposed surface is(111)crystal facet.The test results showed that the NiO nanosheet loaded 1.0% Pt was most highly sensitive to acetone,ethanol and formaldehyde.In this thesis,through the construction of ZnO and NiO,two typical gas sensing materials,some high-performance crystal surfaces are exposed to the surface,which improves the adsorption of the target gas on the surface and the performance of the gas sensor.