First-principles Calculations Of The Electronic Structures And Response Characteristics Of No On Pure And Cu-doped SnO₂

The crystal of SnO2 has good chemical stability, optical properties and mechanical properties, it has been widely applied both in physical and chemical and optical industry. Based on the study of the adsorption of NO on the SnO2(110) surface, it is found that the adsorption will change the system bond length and electronic structure. In addition to this, the catalytic effect of SnO2 to nitrogen oxide is not the same when change the oxygen content of the surface, this is due to the change of the electronic structure around the nitrogen oxides. The SnO2 as an important semiconductor material, has unique optical and electrical properties after doping the Transition metal elements, make the experiment research about SnO2 doping system has been developed rapidly in recent years.In this paper, the calculations are based on density functional theory method of first principles, using the generalized density approximation and the overall energy plane constraint, detecting the adsorption energy, mulliken charge, reaction barrie, absorption spectrum, reflection spectrum and a series of optical properties. In order to more conducive to contrast analysis between crystal, here we select SnO2(110) surface as the research object. Then in order to further explore doping metal on the NO adsorption on the catalyst and catalytic effect, this paper selective doped with copper atoms, the purpose is to explore the copper doping effects on the adsorption process and find the best doping position.First, we will get the stability crystal structure of the SnO2(110), SnO2-x(110), and O2+ SnO2-x(110). Spilled the relaxation of NO on three surfaces of catalysts, through the calculation and analysis of adsorption energy, bond length and charge, we found that NO is easy to adsorb respectively on three substrate at bridge oxygen, oxygen vacancy and the top of adsorption O2. The stable physical adsorption configurations we getted above as the initial state, Simulation to explore the reaction process of NO that occurs in substrates and judge of product types. Through the analysis of the reaction barrier, we found that with the increase of catalyst surface oxygen concentration, the efficiency of NO oxidation will be improved, and generates the NO2 and NO2 ˉ.Second, constructing Cu6c- SnO2(110), Cu5c- Sn O2(110), Cu6c- SnO2-x(110), and Cu5c- SnO2-x(110) Mixed models as substrates, and optimizing the structure of the doped SnO2. We found that doping crystal structures are much more stable than those not doped crystal structures. Analysis and calculate the energy of NO adsorption on two doping configurations, bond length and charge, the most stable adsorption configurations identified. Searching the transition state and compares with each other, the result showed that six ligand doping is easier than five coordination configuration to catalytic NO molecules.Finally, in this paper the optical properties of the unit cell of SnO2 and with a copper atom at the center of the unit cell of SnO2 are analyzed. It was found that doped copper atoms reflection spectrum will have a faint red shift phenomenon, the ability of the nuclear state excitations weakend. The absorption spectrum analysis shows that by SnO2 crystal mixed Cu will have a faint blue shift phenomenon and enhanced the absorption region of the ultraviolet light.