NO与NO2在ZnO表面吸附的密度泛函理论研究

Density Functional Theory Study of NO,NO2 Adsorbed on ZnO（■） Surface

采用DMol3模块中广义梯度密度泛函理论(GGA)的Perdew-Burke-Ernzerh(PBE)方法研究含能材料分解气体产物NO,NO2在ZnO(1010^-)表面的吸附和NO2解离生成NO和O的过程.结果表明,优化后的吸附构型显示Zn顶位为稳定吸附位点,NO2的吸附能大于NO.态密度图分析结合差分电荷密度图表明,NO的N原子与表面Zn有相互作用,电荷从NO转移到表面;NO2的N2p,O2p轨道与表面Zn3d轨道发生杂化,NO2附近积累大量负电荷.过渡态搜索显示NO2的解离需跨过较高能垒,不易进行.

The Perdew-Burke-Ernzerh( PBE) method of generalized gradient approximation( GGA) in DMol3 module was used to study the adsorption behavior of gas products NO and NO2 decomposed by energetic materials( EMs) on ZnO(1010^-) surface and the process of NO2 dissociation to form NO and O. The optimized adsorption configurations show that the top position of Zn on the surface is a stable adsorption site,and the adsorption energy of NO2 is larger than that of NO. The analysis of density of states combined with the deformation charge density shows that the N atom of NO interacts with the surface Zn,and the charge transfers from NO to the surface. The N2p and O2porbitals of NO2 overlaps with the surface Zn3 dorbital,resulting in hybridization and accumulation of a large amount of negative charges near NO2. The transition state search shows that the dissociation of NO2 needs to cross the higher energy barrier and is not easy to carry out. This simple adsorption of small molecular gas reveals the mechanism of action on the surface of ZnO and improves the catalysis of nano-ZnO on EMs.