氢在Ni(410)台阶面的吸附研究

Hydrogen Adsorption on the Stepped Surface of Ni(410)

应用嵌入原子模型(EAM)研究了氢在Ni(410)面的吸附和解离.首先计算单个氢原子在Ni(410)面上的吸附能Ead,吸附键长RH-Ni及吸附高度H0,发现氢在Ni(410)面上有3种相对稳定的吸附位:台面上的赝式四重洞位H1和H2位、台阶底部棱上的LB位和台阶一边棱位B.与低指数面Ni(001)相比,明显增加了台阶棱上的B位以及台阶底部棱上的LB位,相应洞位的吸附性也有增强.说明氢在Ni(410)表面的吸附性受到台阶的影响,从而台阶附近的吸附位增多且吸附性增强;然后计算了H2在Ni(410)表面解离吸附时的活化势垒Ea、吸附能Qad,氢-镍之间键长RH-Ni,构建了解离吸附等势面,计算结果表明台阶处是氢吸附和解离的活跃部位.

The adsorption and dissociation of hydrogen on stepped surface（410） of nickel are studied with the embedded-atom model（EAM） method.The adsorption energy Ead,the length of adsorption bond RH-Ni and the adsorption height H0 are calculated.Three kinds of stable sites are found for hydrogen adsorption.There is the four-fold hollow site H1 and H2 on the terrace surface,the long bridge site LB at the bottom of the step edge and the two-double bridge site B on the step edge.Comparing with hydrogen atom adsorbed on low-index（001） surface,there are two another adsorption sites near the step： the site B on the step edge and the site LB at the bottom of the step edge.The results show that the hydrogen adsorption on Ni（410） is affected by the existence of the step.At the same time,the absorbability of hydrogen atom at the site H1 and H2 is intensified.The active barriers Ea,adsorption energy Qad and acorresponding bond length RH-Ni for dissociation of Hydrogen molecule on stepped surface are calculated.The calculated results show that the dissociation is easier at the bottom of the step.It is shown that the steps are the active sites for hydrogen adsorption and dissociation.