Gas sensor can be used to detect, monitor, monitor, analyze and alarm. It has very important application value in industry, national defense, food safety and medical examination. Among the gas sensors, the semiconductor resistance type gas sensor has many advantages, such as high sensitivity, fast response, small size, light weight, easy to carry, and so on. As one of the widely used gas sensing materials, SnO2 has been a hot spot in the research and application in 60s, and it has been developing rapidly. SnO2 is one of the most common gas sensitive materials, with physical and chemical properties of gas detection and stability; reversible adsorption and desorption time is short; low cost, energy saving and other advantages, is widely used in the detection of various gas sensitive devices. However, the disadvantages of high working temperature and poor selectivity of SnO2 make it need to be further improved as gas sensitive material. The gas sensing mechanism of semiconductor gas sensitive material is mostly controlled by the surface, which is embodied in: increasing the specific surface area of the material and enhancing the gas sensing performance. At present, the main method of increasing the specific surface area of the material is nano scale. In this paper, the preparation and gas sensing properties of porous and hollow structure SnO2 are mainly discussed on the basis of particle size. Porous structure facilitates the increase of the specific surface area of the material, providing a larger surface area and volume ratio for the material, which is of great benefit to the diffusion and transportation of the gas being measured. Nano hollow structure has a thin shell; the inner and outer surface provides a high surface area and volume ratio, so that the sensor has a faster response and recovery speed, and higher sensitivity. Using carbon micro spheres as hard templates, the structure of SnO2 was successfully prepared by using different raw materials ratio and hydrothermal conditions. The composition and morphology of SnO2 were characterized by XR.D, SEM, TEM and so on. The study of gas sensitivity shows that the SnO2 of the hollow classification structure can show good gas sensitivity, which has the advantages of high sensitivity, good selectivity and strong stability.
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