Research Center for Applied Sciences, Academia Sinica, 128 Sec. 2 Academia Road, Taipei 11529, Taiwan.
J Chem Phys. 2011 Aug 14;135(6):064707. doi: 10.1063/1.3624524.
Growth of large-area, few-layer graphene has been reported recently through the catalytic decomposition of methane (CH(4)) over a Cu surface at high temperature. In this study, we used ab initio calculations to investigate the minimum energy pathways of successive dehydrogenation reactions of CH(4) over the Cu (111) surface. The geometries and energies of all the reaction intermediates and transition states were identified using the climbing image nudged elastic band method. The activation barriers for CH(4) decomposition over this Cu surface are much lower than those in the gas phase; furthermore, analysis of electron density differences revealed significant degrees of charge transfer between the adsorbates and the Cu atoms along the reaction path; these features reveal the role of Cu as the catalytic material for graphene growth. All the dehydrogenation reactions are endothermic, except for carbon dimer (C(2)) formation, which is, therefore, the most critical step for subsequent graphene growth, in particular, on Cu (111) surface.
最近有报道称，通过在高温下在 Cu 表面催化分解甲烷（CH(4)），可以生长出大面积的少层石墨烯。在这项研究中，我们使用从头算计算方法研究了 CH(4)在 Cu(111)表面上连续脱氢反应的最小能量途径。使用提升图像键合弹性带方法确定了所有反应中间体和过渡态的几何形状和能量。与气相相比，CH(4)在该 Cu 表面上的分解的活化能要低得多；此外，电子密度差的分析表明，在反应路径上，吸附物与 Cu 原子之间存在显著程度的电荷转移；这些特征揭示了 Cu 作为石墨烯生长的催化材料的作用。所有脱氢反应都是吸热的，除了二聚碳（C(2)）的形成，因此，这是后续石墨烯生长的最关键步骤，特别是在 Cu(111)表面上。
