Enhancing the Strength of Graphene by a Denser Grain Boundary

Abstract

From a device application point of view, the extreme mechanical strength of graphene is highly desirable. However, the unavoidable polycrystalline nature of graphene films produced by chemical vapor deposition (CVD) leads to significant fluctuations in mechanical properties. Although the effects of atomic defects or grain boundaries (GBs) on mechanical strength have been widely studied and some modifications have been applied to enhance the stiffness of graphene, the problems of fragility as well as significantly reduced breaking strength arise. Here we report a systematic study on the effect of elastic modulus and breaking strength of CVD-derived graphene films with a controlled density and distribution of GBs. We find that graphene films become much stronger by hugely increasing the density of GBs without triple junctions (TJs) formed inside, in analogy to the two-dimensional (2D) plum pudding structures. The comprehensive performance with a 2D Young's modulus of 436 N/m (∼1.3 TPa) and 2D breaking strength of 43 N/m (∼128 GPa) can be achieved with the average grain size of 20 nm. Moreover, the existence of TJs will slightly reduce the strength in these GB structures. Due to defect types, the graphene films will show various tearing behaviors after indentation. All these mechanical studies of GBs provide a guideline to obtain the optimal performance of 2D materials through GB structure engineering.

Robust ultraclean atomically thin membranes for atomic-resolution electron microscopy

“…1c) [29][30][31][32] . Considering the theoretical strength of pristine graphene monolayer is~120 GPa 33 , high-quality monolayer graphene membrane without linear defects will remain intact during drying (Fig. 1b, c, Supplementary Fig.…”

Substrate Engineering for CVD Growth of Single Crystal Graphene

“…But on the other hand, the electronic (e.g., bandgap), physical, chemical (e.g., catalytic activity), and mechanical properties (e.g., Young's modulus and strength) of the graphene film can be modulated by controlling the density, dimensions, and distributions of GBs. [ 16–19 ] Although GB engineering is undoubtedly an interesting topic to discussed separately, it is beyond the scope of this article.…”

Nanomechanical behavior and interfacial deformation beyond the elastic limit in 2D metal–organic framework nanosheets

“…[18][19][20][21] This includes the use of atomic force microscope (AFM)-based nanoindentation and the instrumented nanoindentation techniques. 22 Thus far, studies have concentrated on either the ultra-stiff nanosheets, graphene (Young's modulus, E $ 1 TPa) 20,[23][24][25] and boron nitride (E $ 250 GPa) in particular, 17,26 or the very so biological samples such as protein nanosheets. 27 Although there are a few experiments performed on nanosheets with stiffness lying in the range of a few gigapascals to tens of gigapascals, such as the dense 2-D hybrid framework of Mn 2,2-dimethylsuccinate nanosheets (E ¼ 9.4-20.9 GPa depending on crystal orientation due to anisotropy) 28 and the bismuth telluride nanosheets (E ¼ 11.7-25.7 GPa), 29 very few studies have systematically explored the mechanical behavior of nanoporous MOF nanosheets.…”