SO_(2)和NO_(2)在γ-Al_(2)O_(3)(110)表面吸附的第一性原理计算

First-principles calculation of SO_(2) and NO_(2) adsorbed on γ-Al_(2)O_(3)(110) surface

采用基于平面波基组的Vienna Ab-initio Simulations Package (VASP)程序研究了SO_(2)和NO_(2)在γ-Al_(2)O_(3)(110)表面和羟基化γ-Al_(2)O_(3)(110)表面的吸附,获得了SO_(2)和NO_(2)吸附的不同构型和结构参数.对吸附能,电荷转移,差分电荷密度和投影态密度等进行分析和讨论.对比发现,在γ-Al_(2)O_(3)(110)表面SO_(2)的吸附能力强于NO_(2).SO_(2)或NO_(2)在非羟基化γ-Al_(2)O_(3)(110)表面吸附时O原子的2p轨道和Al原子的3s3p轨道作用形成O-Al键,且SO_(2)吸附时键结强度高于NO_(2).NO_(2)吸附时费米能级以下有部分反键态,削弱了与γ-Al_(2)O_(3)(110)表面相互作用.在羟基化γ-Al_(2)O_(3)(110)表面SO_(2)或NO_(2)的吸附能力会低于非羟基化表面,但是SO_(2)的吸附能力依旧强于NO_(2).计算结果说明SO_(2)与γ-Al_(2)O_(3)(110)表面的相互作用强于NO_(2).以上研究,将有助于理解SO_(2)和NO_(2)在γ-Al_(2)O_(3)的反应性,为进一步研究它们的非均相转化和在灰霾形成中的促进作用奠定基础.

In order to explore the mechanism of heterogeneous reaction of SO_(2) and NO_(2) on the surface of mineral particles,we studied the adsorptions of SO_(2) and NO_(2) on the clean surface and hydroxylated surface of γ-Al_(2)O_(3)(110) by density functional theory. We calculated and obtained the different adsorption configurations and structural parameters of SO_(2) and NO_(2). Then we analyzed and discussed the adsorption energy,charge transfer,deformation charge density and projected state density. It is found that the adsorption capacity of SO_(2) on the surface of γ-Al_(2)O_(3)(110) is higher than that of NO_(2). When SO_(2) or NO_(2) adsorbs on the surface of γ-Al_(2)O_(3)(110),the2 p orbital of O atom and the 3s3p orbital of Al atom interact to form O-Al bond,and the bond strength of O-Al bond that SO_(2) formed is higher than that of NO_(2). The p COHP of NO_(2) adsorption shows antibonding in an occupied band,which weakens the interaction with the γ-Al_(2)O_(3)(110) surface. The adsorption capacity of SO_(2) or NO_(2) on the surface of hydroxylated γ-Al_(2)O_(3)(110) is lower than that on clean γ-Al_(2)O_(3)(110) surface,but the adsorption capacity of SO_(2) is still stronger than that of NO_(2). These results make us infer that the interaction between SO_(2) and γ-Al_(2)O_(3)(110) surface is stronger than that of NO_(2). The study will help to understand the reactivity of SO_(2) and NO_(2) on γ-Al_(2)O_(3),and lay a foundation for further study of their heterogeneous transformations and the cause of haze.