Altering the Properties of Graphene on Cu(111) by Intercalation of Potassium Bromide

Abstract

The catalytic growth on transition metal surfaces provides a clean and controllable route to obtain defect-free, monocrystalline graphene. However, graphene’s optical and electronic properties are diminished by the interaction with the metal substrate. One way to overcome this obstacle is the intercalation of atoms and molecules decoupling the graphene and restoring its electronic structure. We applied noncontact atomic force microscopy to study the structural and electric properties of graphene on clean Cu(111) and after the adsorption of KBr or NaCl. By means of Kelvin probe force microscopy, a change in graphene’s work function has been observed after the deposition of KBr, indicating a changed graphene–substrate interaction. Further measurements of single-electron charging events as well as X-ray photoelectron spectroscopy confirmed an electronic decoupling of the graphene islands by KBr intercalation. The results have been compared with density functional theory calculations, supporting our experimental findings.

Reconstruction of a 2D layer of KBr on Ir(111) and electromechanical alteration by graphene

“…Clusters of three KBr units are periodically formed to minimize the overall adsorption energy. The calculated adsorption energy for the 12 × and for the larger 12 × 2 configuration is in both cases −5.31 eV/nm 2 (−0.82 eV/unit, the adsorption energy in a unit cell) and thus stronger than on Cu(111), where it was −2.43 eV/nm 2 [ 18 ]. Calculation of the specific adsorption energies of K and Br and their distance from the Ir surface at the equilibrium geometry revealed that fcc or hcp threefold hollow sites are more favorable for the adsorption.…”

“…Figure 4a shows a large-area topography of the Ir(111) surface, half of which is covered by graphene and additionally less than one monolayer of KBr. For Cu(111), KBr intercalation, which induces a decoupling of the graphene layer from the metal substrate, was observed with a similar preparation [ 18 ]. Here, different types of KBr patterns are found in separated regions with and without graphene.…”

“…Besides the stacking of different monolayers, the intercalation of a third ma- terial between a substrate and a 2D layer can be applied to tune the physical properties [13][14][15][16][17]. Schulzendorf et al reported the electrical decoupling of graphene islands by the intercalation of single layers of KBr between the Cu(111) metal substrate and graphene, resulting in quasi free-standing graphene layers [18].…”

On‐Surface Synthesis of Nitrogen‐Doped Kagome Graphene

“…Our preliminary computational results indicate that three additional electrons injected in the N‐KG would promote a ferromagnetic state (see Figure S8). Although local charging of individual π‐extended tetraazapentacenes (the electron‐poor counterpart of the semiconductor pentacene) [37] is experimentally possible by tip gating (Figure S3), [38] such quantum phase transition would require to electronically decouple the entire N‐KG from the metallic substrate [39] …”

On‐Surface Synthesis of Nitrogen‐Doped Kagome Graphene

“…to electronically decouple the entire N-KG from the metallic substrate. [39] In summary, we employed an Ullmann coupling reaction for the bottom-up synthesis of N-doped Kagome graphene on Ag(111). The reaction of linear ditopic TBQP precursors is steered by an organometallic intermediate leading to triangular nodes and a long-range honeycombed Kagome lattice.…”