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Adsorption and diffusion of gold adatoms on graphene nanoribbons: An ab initio study

机译：石墨烯纳米带上金原子吸附和扩散的从头算研究

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We have performed a theoretical ab initio investigation, within the density-functional theory, of Au adatoms on graphene nanoribbons (Au/GNRs). We have considered armchair GNR (A-GNR) and zigzag GNR (Z-GNR). For both systems, we find an energetic preference for Au adatoms lying along the edge sites. Our calculated adsorption energies, 1.01 eV and 2.18 eV for Au adatoms on the A-GNR and Z-GNR, respectively, indicate the formation of Au-C covalent bonds. Au atoms can adsorb more easily along the zigzag edges than along the armchair edges. In addition, we examined the diffusion barriers of Au adatoms on those ribbon systems. We have considered a number of Au diffusion paths perpendicular as well as parallel to the ribbon growth directions. Our calculated energy barriers indicate that the segregation of Au adatoms from the inner sites toward the edge sites is a quite likely process. In this case, we hnd a net energy barrier of ～80 meV. In contrast, the Au adatoms will face higher energy barriers for diffusion paths along the edge sites of the ribbons. The electronic-structure calculations indicate that the semiconducting character of the GNRs has been kept for low concentration of Au adatoms. Meanwhile, by increasing the concentration of Au adatoms along the edge sites, the Au/GNR systems become metallic.
机译：我们已经在密度泛函理论范围内对石墨烯纳米带（Au / GNRs）上的Au原子进行了从头开始的理论研究。我们考虑了扶手椅GNR（A-GNR）和曲折GNR（Z-GNR）。对于这两种系统，我们都发现沿边缘位点的金原子吸附原子充满活力。我们计算出的A-GNR和Z-GNR上Au原子的吸附能分别为1.01 eV和2.18 eV，表明形成了Au-C共价键。金原子沿锯齿形边缘的吸收比沿扶手椅边缘更容易吸收。另外，我们检查了在这些带状系统上金吸附原子的扩散势垒。我们已经考虑了许多垂直于和平行于带生长方向的金扩散路径。我们计算出的能垒表明，Au原子从内部位置向边缘位置的分离是一个很可能的过程。在这种情况下，我们的净能垒为〜80 meV。相比之下，Au吸附原子将面临更高的能垒，以沿着碳带边缘位置扩散。电子结构计算表明，对于低浓度的金吸附原子，GNR的半导体特性得以保持。同时，通过增加沿边缘部位的Au原子的浓度，Au / GNR系统变为金属。

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