摘要
采用密度泛函理论广义梯度近似平面波赝势法结合周期平板模型,研究F离子在γ-Al_2O_3(110)非极性表面的吸附行为,分析了F^-离子在其表面不同吸附位以及不同覆盖度下吸附构型和电子特性。结果表明:表面配位不饱和的Al为F^-离子活性吸附位,F离子在γ-Al_2O_3(110)表面化学吸附后形成F-Al键促使F^-离子活化;F^-离子在Al_Ⅲ(1)桥位吸附时最稳定。随着覆盖度增加,吸附能增大,F离子与表层原子的距离(d_(F^--surf)缩短:同时表面吸附F离子引起表层及次表层原子层间距发生不同程度偏移,最大幅度为10.07%。差分电荷密度与电子态密度分析指出,F离子在γ-Al_2O_3(110)表面吸附主要是由F^-离子2s和2p轨道与γ-Al_2O_3基底Al的3p轨道相互作用所致。
The adsorption of F anion on γ-Al2O_3（110） non-polar surface has been studied with periodic slab model by PW91 approach of GGA using density functional theory （DFT）. The adsorption configurations and electronic property for F anion on γ-Al2O_3（110） surface at various adsorption sites and different coverages were analyzed. The calculated results indicate that the F anions tend to adsorb on the unsaturated coordination AI atoms at the furface. Strong chemisorption occurs, and F-Al structures form when F anions adsorb on the furface. Under these conditions, the F anions are activated and may have possibility to participate in next step chemical reaction. The bridge site of Alm（1） where F anion adsorbed on γ-Al2O_3（110） surface is energetically stable. Moreover, the adsorption energy decreases with the increasing of coverage, while the vertical separation between adsored F and the surface layer atoms shortens. Meanwhile, the F anions adsorption leads to the different degrees of skewing of the space between the surface and subsurface atom layer, the biggest one reach up to 10.07 %. Charge density difference and density of states indicated that the adsorption behavior is dominated by the interaction between the 2s, 2p orbit ofF anion and the 3p orbit of the base metal Al on the surface.
出处
《计算机与应用化学》
CAS
2015年第2期147-151,共5页
Computers and Applied Chemistry
基金
高等学校博士学科点专向科研基金资助项目(20110006110003)
国家自然科学基金资助项目(51434005)
