First-principles Calculations Of Tin Oxide Low-dimensional Nanostructure

At present, semiconductor gas sensor is widely used as substrate in SnO₂ by doping methods such as gas sensitive sensor material preparation. SnO₂ is the n-type semiconductor material of the direct wide band gap. Has been widely applied in optoelectronic devices, gas sensors, photocatalyst, nano-sieve membrane, glass coatings, transparent electrodes of solar cells and lithium-ion battery anode material and so on. As gas sensitive materials, it is difficult to meet the high sensitivity and selectivity, good stability, operating temperature and room temperature, low energy consumption and shorter recovery time corresponding at the same time. At low temperature, it is difficult to react with the outside world, so the sensitivity is low. Although the high sensitivity at a higher temperature, the energy consumption is higher, and will be reduced the service life of gas sensor. It has been found to reduce the single particle component specifications can increase the specific surface area, thus enabling a significant increase in sensitivity and reducing power consumption. Therefore, the study of SnO₂ gas-sensing materials tends to the direction of the nano-structured. At present, the study of SnO₂ is focused on SnO₂ thin film prepared by experiment and analysis of SnO₂ thin film resistance changes through gas adsorption at the surface in the film. The main issue is that the mechanism of adsorption is not clear and we want to further improve the sensitivity and selectivity of gas by studying the different morphology and crystal structure on the adsorption characteristics of gas sensors.In this paper, based on Density Functional Theory using the SIESTA software on low-dimensional structure of SnO₂ First-principles calculation to study the characteristics of quantum mechanics and adsorption mechanism. The principal elements are listed as follows: 1. The conductance of rutile structure of SnO₂ nanowires is investigated with the method of LCAO combined with normconversing pseudopotential. Theoretical calculations show that the structural properties of nanowires are relevant with its electronic configuration and the conductivity. Based on DFT, studies the structural properties and electronic properties of the smaller size of SnO₂ nanowires. It shows that the properties of bonding and the DOS structure of the rutile crystal structure is the same to the bulk materials DOS structure, which is in line with the current understanding of its.2. Low-dimensional structure of SnO₂ absorbing CO is investigated, Theoretical calculations show that the binding of the SnO₂ molecule to the CO grain is being and its features are similar to the bulk materials. The analysis of the grain structure and electronic configuration shows that: First, CO is adsorbed only parallel to the (1 0 0) axis on the SnO₂ surfaces. Second, adsorption derives from the rearrangement of the entire grain structure, rather than from a displacement of the surface atoms nearest to the molecule. Third, the grain and the molecule forms an unique, stably bonded complex.