| With the development of MEMS technology, researches into metal oxide gas sensors have increased. These sensors are widely used for the detection of the poisonous gas, industrial waste gas and polluting gas, et al. SnO2, one of this kind of materials, is used the most widely, which has unique surface and interface properties as there are a lot of 0 vacancies on the bulk surfaces at different temperatures, and sheer conductance measurement indicates the conductance increases by two levels as the existence of 0 vacancies. As a result, it is useful to study the surface electronic structure and adsorption theoretically for improving the performance of the sensors.In this paper, the electronic structures and adsorptions of SnO2(110) surface are studied for the perspective of improving the performance of the sensors. Firstly, four models of SnO2(110) oxidized, partially oxidized, reduced and deficient surfaces are built followed by structure optimizing, and then the electronic structures (band structure, DOS, atom population, electron density) of surfaces are calculated with the DFT theory combining with plane-wave pseudo-potential and super-cell methods. The effects of 0 vacancies on the electronic structures of surfaces are mainly analyzed. Based on the studies of the four type of surfaces, the adsorption of O2 on SnO22(l 10) reduced surface is further studied. Several adsorption sites of the O2 molecule along [110], [001], [1-10] directions are tried. As three steady adsorption structures are obtained, the electronic structures of the adsorption system are further calculated and the effects of O2 adsorption on the surface properties are also analyzed.At last, based on the studies on electronic structures and adsorptions of SnO2(110) surfaces, it is pointed out that the temperature and the environmental O2 would affect the sensor performance, and advices for improving the performance of sensors and the future work are proposed.
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