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本文用密度泛函理论(DFT)的总能计算研究了一氧化碳和氢原子在Ni(111)表面上p(2×2)共吸附系统的原子结构和电子态,结果表明CO和H原子分别被吸附于两个对角p(1×1)元胞的hcp和fcc位置.以氢分子和CO分子作为能量参考点,总吸附能为2.81eV,相应的共吸附表面功函数φ为6.28eV.计算得到的C—O,C—Ni和H—Ni的键长分别是1.19,1.96和1.71,并且CO分子以C原子处于hcp的谷位与金属衬底原子结合.衬底Ni(111)的最外两层的晶面间距在吸附后的相对变化分别是+1.6%(Δd12)和+0.4%(Δd23).对于Ni(111)表面CO和氢原子p(2×2)单吸附结构,计算结果表明在Ni(111)p(2×2)/H表面吸附系统中,fcc位置吸附的氢原子其能量最低,吸附高度是0.90;而在Ni(111)p(2×2)/CO表面中,hcp位置吸附的CO其能量最低,吸附高度是1.33.在Ni(111)p(2×2)/(CO+H)中每个CO和H原子之间的相互作用能约为0.60eV.由于Ni(111)的存在使得CO和H原子作用增强,为更好地理解Ni(111)作为催化表面在Fisher-Tropsch反应中的作用提供了一定的基础.
In this paper, the atomic structure and electronic states of the p (2 × 2) co-adsorption system of carbon monoxide and hydrogen on the surface of Ni (111) have been studied by the total energy calculations of density functional theory (DFT) Adsorbed on the hcp and fcc sites of two diagonal p (1 × 1) cells.The total adsorption energy was 2.81eV with the hydrogen molecule and CO molecule as energy reference points, and the corresponding co-adsorption surface work function φ was 6.28eV. The calculated bond lengths of C-O, C-Ni and H-Ni are 1.19, 1.96 and 1.71, respectively, and the CO molecule binds to the metal substrate atoms with C atoms in the valley of hcp. The relative changes of the interplanar spacings in the outermost two layers were + 1.6% (Δd12) and + 0.4% (Δd23), respectively.For the single adsorbed structure of CO and hydrogen atoms on the Ni (111) surface, The calculated results show that the hydrogen atom adsorbed on fcc possesses the lowest energy at a Ni (111) p (2 × 2) / H surface adsorption system with an adsorption height of 0.90. In Ni (111) p (2x2) / CO In the surface, the CO adsorbed at the hcp position has the lowest energy and the adsorption height is 1.33 The interaction energy between each CO and H atom in Ni (111) p (2x2) / (CO + H) is about 0.60 eV. Due to the presence of Ni (111) CO and H atoms make the role of enhanced A better understanding of the role of Ni (111) as a catalyst surface in the Fisher-Tropsch reaction provides a basis.