First-principles study of metal adatom adsorption on graphene

Abstract

The adsorption of 12 different metal adatoms on graphene is studied using first-principles density-functional theory with the generalized gradient approximation. The adsorption energy, geometry, density of states ͑DOS͒, dipole moment, and work function of each adatom-graphene system are calculated. For the adatoms studied from groups I-III of the Periodic Table, the results are consistent with ionic bonding, and the adsorption is characterized by minimal change in the graphene electronic states and large charge transfer. For transition, noble, and group IV metals, the calculations are consistent with covalent bonding, and the adsorption is characterized by strong hybridization between adatom and graphene electronic states. For ionically bonded adatoms, the charge transfer is calculated quantitatively using two methods, one based on the DOS and the other based on the real-space-charge density. A variation in dipole moments and work-function shifts across the different adatoms is observed. In particular, the work-function shift shows a general correlation with the induced interfacial dipole of the adatom-graphene system and the ionization potential of the isolated atom.

Giant photoeffect in proton transport through graphene membranes

“…Within the resolution of our measurement, ±60 meV, we did not observe a significant change in E under illumination. Second, the photo-proton effect was also observed for graphene membranes decorated with other catalytically-active metals [18][19][20] such as Pd and Ni. In both cases, we observed the same power dependence I ∝ P 1/4 as for Pt but the effect was a factor of ~2 weaker for both Pd and Ni ( Supplementary Fig.…”

“…We note that Pd, Pt and Ni are known to strongly interact with graphene 18-21 and provide n-type (electron) doping [18][19][20] . In contrast, if we used nanoparticles of Au, a metal that weakly interacts with graphene and p-dopes it 18,20 , the proton current remained unaffected even by our strongest illumination (100 mW cm -2 ). Hence, the mechanism behind the photo-proton effect must be consistent with the following observations.…”

Structural and electronic properties of the Ptn–PAH complex (n = 1, 2) from density functional calculations

“…For example, adsorption of different metal adatoms on graphene has been studied 10 , electronic and magnetic properties of graphene functionalized by 3d transition-metal atoms have been investigated 12 , and electronic structures and magnetic properties of transition metal M (Fe, Co, Ni, and Cu) adatom and dimer adsorbed on graphene have been studied 11 . Platinum nanoparticles occupy a privileged position as a catalyst in industrial applications 16 .…”

“…In this regard, it is necessary to understand the microstructure of Pt/C to analyze the interaction between the Pt atoms and the carbon surface, and to investigate the stability of Pt nano-particles on carbon materials. There are several theoretical efforts devoted to an improved understanding of the Pt-C interaction [10][11][12][13][14][15][26][27][28][29][30][31][32][33][34][35][36][37] . Kong et al, investigated the single Pt-atom adsorption on a carbon nanotubes (CNTs) and graphite nano-fibers (GNFs) 27 , and observed strong adsorption on atomic vacant sites or graphene edges.…”

“…Howells and co-workers 40 investigated the influence of substrate defect sites on the morphology of Pt vapor deposited on the basal plane of HOPG by XPS and STM and indicated that the interaction between a Pt cluster and HOPG depends on the surface condition of HOPG. Density functional theory (DFT) has become an invaluable tool in studying the interaction between metal clusters and graphene at the atomic level [9][10][11][12][13][14][15] . However, when considering this type of interaction, the effect of dispersion forces becomes important, as for example in the adsorption of aromatic molecules on metal surfaces [41][42][43][44][45][46][47] .…”