The Preparation And Gas Sensitive Performance Study Of Porous/hollow SnO₂

Due to the gas sensor can detection, monitoring, analysis and give an alarm for gas being measured, so it has very important value in industry, national defense, food safety and medical tests, and other fields. In many classification of gas sensors, the type of semiconductor resistance gas sensor get the favour of people because of their high sensitivity, fast response speed, small volume, light weight and easy to carry. SnO2 as a kind of widely used sensitive material, become the focus of research in the 1960 s, and has a very fast development. SnO2 is one of the most common gas sensitive materials, has merits of the stability properties of physical and chemical; reversible with gas detection, adsorption and desorption time were short; low cost; save energy consumption, is widely used in the sensitive detection of various gas components. Howere, the higher working temperature and poor selectivity of SnO2 remains to be further perfect.Most of gas-sensing mechanism of semiconductor gas sensitive materials are the type of controlled by the surface, means that the gas sensitive performance will be enhanced with the increase of specific surface areas. In the present researches, the main method of increasing the specific surface area of material is the formation of nanoparticle.This paper is mainly discussed the preparation and gas sensitive performance study of SnO2 with porous/hollow structures. Porous structure has advantage of increasing the specific surface area of material, providing a larger surface area and volume ratio, which is beneficial to the diffusion and transportation of gas. Hollow structure has hin shell, the inside and outside surfaces provide a higher surface area and volume ratio, which made the sensors have quicker response and recovery speed and higher sensitivity. The specific methods as follows:1. The synthesis of porous SnO2 through the FA template and the phase separation methods. The structures and morphologies of SnO2 were investigated by X-ray diffraction(XRD) and scanning electron microscopy(SEM). Gas-sensing property of SnO2 with porous structure by FA templating method to ethanol was tested, shown a rapid response and recovery,SnO2 with porous structure by phase separating method shown a excellent sensing performance to ethanol.2. The synthesis of hollow hierarchical SnO2 through hard template. Using carbonmicrospheres as hard template, through exploring the different raw materials ratio and the hydrothermal conditions, we successfully synthesis the SnO2 with hollow hierarchical structure under the hydrothermal reaction. The structures and morphologies of SnO2 with hollow hierarchical structure were investigated by several techniques, such as XRD, SEM and TEM. Gas sensitive test reveled that the SnO2 with hollow hierarchical structure shown an excellent sensing performance to ethanol, has the merits of high sensitivity, good selectivity and strong stability.3. The synthesis of hollow polyhedron SnO2 through self-templating. We used ZnSn(OH)6 and CoSn(OH)6 as the precursors, successfully synthesis hollow precursors with pure phase and dispersed particals with uniform size. On this basis, The SnO2 with porous/hollow structure need further studied.