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

作者：Brito W H^*; Miwa R H

来源：Physical Review B, 2010, 82(4): 045417.

DOI：10.1103/PhysRevB.82.045417

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 find a net energy barrier of similar to 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.

• 出版日期2010-7-20