Orientation‐Dependent Strain Relaxation and Chemical Functionalization of Graphene on a Cu(111) Foil

Abstract

Epitaxial graphene grown on single crystal Cu(111) foils by chemical vapor deposition is found to be free of wrinkles and under biaxial compressive strain. The compressive strain in the epitaxial regions (0.25-0.40%) is higher than regions where the graphene is not epitaxial with the underlying surface (0.20-0.25%). This orientation-dependent strain relaxation is through the loss of local adhesion and the generation of graphene wrinkles. Density functional theory calculations suggest a large frictional force between the epitaxial graphene and the Cu(111) substrate, and this is therefore an energy barrier to the formation of wrinkles in the graphene. Enhanced chemical reactivity is found in epitaxial graphene on Cu(111) foils as compared to graphene on polycrystalline Cu foils for certain chemical reactions. A higher compressive strain possibly favors lowering the formation energy and/or the energy gap between the initial and transition states, either of which can lead to an increase in chemical reactivity.

Stress‐Transfer‐Induced In Situ Formation of Ultrathin Nickel Phosphide Nanosheets for Efficient Hydrogen Evolution

“…[13] An AFM image revealed wrinkled FGR covered with Ni 2 PN Ss,w ith an overall thickness of about 3.2 nm (Figure 2c). [14] Considering that the average thickness of as ingle Ni 2 Pl ayer is approximately 2.4 nm ( Figure S4), the apparent thickness of graphene is about 0.8 nm, which is consistent with the thickness of monolayer FGR. Theu ltrathin 2D Ni 2 Ps tructure was further confirmed by TEM analysis (Figure 2d).…”

Anisotropic Strain Relaxation of Graphene by Corrugation on Copper Crystal Surfaces

“…Considering the distinct atomic configurations of Cu crystal surfaces, both strain level and direction are different for graphene grown on them. Recently, a few groups have reported that graphene grown on Cu(111) can be free of wrinkle due to the strong interfacial coupling or large friction force between graphene and Cu(111). However, the detailed corrugation process of graphene on various Cu crystal surfaces, including the existence and extent of step bunches, the distribution of graphene wrinkles, and their relationship for the strain relaxation, are not fully revealed.…”

Oxidative Originators of Graphene Barrier Coating Grown on Surfaces

“…And the authors attributed this heterogeneous oxidation strength of graphene-Cu system to the degree of latticealignment, which results in a varying average height of carbon atoms above the global Cu surface. As well as, Li et al's experiments and calculations [108] also proved that CVD graphene epitaxially grown on the single crystal Cu(111) surface has much friction with the substrate, forming an obvious energy barrier and inhibiting the formation of wrinkles in graphene, thus inhibiting the corrosion of Cu.…”