School of Physics, The University of Sydney, NSW 2006 Sydney, Australia.
J Phys Condens Matter. 2010 Dec 1;22(47):475005. doi: 10.1088/0953-8984/22/47/475005. Epub 2010 Nov 15.
The properties of hydroxyl groups on C(111)-(1 × 1) and reconstructed (2 × 1) surfaces at different sites and for various coverages are investigated using density functional theory. Out of the adsorption sites considered, i.e. face centred cubic, hexagonal close packed, on-top and bridge sites, the on-top site is the most stable for OH on the C(111)-(1 × 1) surface for all coverages. On the reconstructed (2 × 1) surface the on-top site is the preferred configuration. Adsorption of OH was not stable however at any site on the reconstructed C(111)-(2 × 1) relative to the (1 × 1) surface; thus adsorption of OH leads to the de-reconstruction of the former surface. Both the 0.5 and 1 monolayer (ML) coverages were able to lift the (2 × 1) surface reconstruction. Repulsion between the OH adsorbates on the (1 × 1) surface sets in for coverages greater than 0.5 ML. A general decrease in the work function with increasing OH coverage was observed on both the (1 × 1) and (2 × 1) surfaces relative to the values of their respective clean surfaces. Regarding the electronic structure, O 2p states on the reconstructed (2 × 1) surface are observed at around - 21, - 8.75 , - 5 and - 2.5 eV, while O 2s states are present at - 22.5 eV. On the (1 × 1) surface (for 0.33 ML in the on-top site), O 2p states occurred between - 8 and - 9 eV, - 5 and - 4 eV and at around - 2.5 eV. O 2s states are established between - 22.5 and - 21 eV. The valence band width is 21 eV, and a hybrid 2s/2p state that is characteristic of diamond is located at about 12.5 eV below the valence band minimum.
使用密度泛函理论研究了 C(111)-(1×1) 和重构(2×1)表面在不同位置和不同覆盖度下的羟基性质。在所考虑的吸附位置中，即面心立方、六方密堆积、顶位和桥位，对于所有覆盖度，OH 在 C(111)-(1×1)表面上的最稳定吸附位置是顶位。在重构(2×1)表面上，顶位是首选构型。然而，相对于(1×1)表面，OH 在重构 C(111)-(2×1)表面上的任何位置都不稳定，因此，OH 的吸附导致前一个表面的去重构。0.5 和 1 单层(ML)覆盖度都能够提升(2×1)表面的重构。在(1×1)表面上，随着 OH 吸附物覆盖度的增加，排斥力开始起作用。与各自清洁表面的数值相比，在(1×1)和(2×1)表面上都观察到随着 OH 覆盖度的增加而导致功函数的普遍下降。对于电子结构，在重构(2×1)表面上，O 2p 态出现在大约-21、-8.75、-5 和-2.5 eV，而 O 2s 态出现在-22.5 eV。在(1×1)表面(在顶位上的 0.33 ML)，O 2p 态出现在-8 和-9 eV、-5 和-4 eV 以及大约-2.5 eV。O 2s 态位于-22.5 和-21 eV 之间。价带宽度为 21 eV，一个位于价带最小值以下约 12.5 eV 的特征金刚石的混合 2s/2p 态。
