Graphene on Ru(0001): Contact Formation and Chemical Reactivity on the Atomic Scale

Abstract

Graphene on Ru(0001) is contacted with Au tips of a cryogenic scanning tunneling microscope. The formation and conductance of single-atom contacts vary within the moiré unit cell. Density functional calculations reveal that elastic distortions of the graphene lattice occur at contact due to a selectively enhanced chemical reactivity of C atoms at hollow sites of Ru(0001). Concomitant quantum transport calculations indicate that the graphene-Ru distance determines the conductance variations.

Tuning dissociation using isoelectronically doped graphene and hexagonal boron nitride: Water and other small molecules

“…This example in 2CBN demonstrates that inductive effects from neighbouring atoms dominate over steric effects. Despite the advantage of satisfying the sp 3 hybridisation in trans-adsorption states, it is important to remember that in practice 2D materials are often suspended or grown over substrates [68][69][70][71][72][73][74][75][76] (metals or silicon carbide) where cis configurations are more likely.…”

“…69,71,72 It is also known that differences in the lattice constants of the 2D material and support can lead to an undulating moiré structure in which different regions of the 2D overlayer interact differently with the substrate. 68,70,73,75,76 It would be interesting in future work to explore how the presence of a substrate alters the trends observed here.…”

“…We have not included supporting materials in this study but the electronic properties of graphene and h-BN can be influenced by the choice of support. [68][69][70][71][72][73][74][75] Metals, for instance, can hybridise the p z -states in graphene and the N atoms in h-BN, and thus alter the reactivity of the surfaces. 69,71,72 It is also known that differences in the lattice constants of the 2D material and support can lead to an undulating moiré structure in which different regions of the 2D overlayer interact differently with the substrate.…”

Structure and local variations of the graphene moiré on Ir(111)

“…5,[17][18][19][20][21] The graphene-substrate interaction depends on the metal, leading to a variation in the electronic and topographic structure of the moiré, 5 and reactivity of the graphene layer. [22][23][24][25][26][27] The structure of the moiré on the weakly bound systems has proven to be particularly difficult to study experimentally. In STM the contrast of the moiré on G/Ir(111) inverts as a function of bias and tip termination 22,23 and the results of AFM experiments depend on the tip reactivity and the tip-sample distance.…”

Probing growth dynamics of graphene/Ru(0001) and the effects of air exposure by means of helium atom scattering

“…The lattice mismatch (9%) between C and Ru causes the formation of an incommensurate or reconstructed interface [12][13][14]. Scanning tunneling microscopy (STM) measurements display a periodically rippled hexagonal pattern with a lattice constant of 30 Å (about 12 graphene unit cells) overlaid on 11 Ru(0001) unit cells [15][16][17].…”