期刊
ACS NANO
卷 12, 期 5, 页码 4529-4535出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b00869
关键词
nanocrystalline graphene; grain boundary; AFM nanoindentation; mechanical properties; breaking strength
类别
资金
- National Natural Science Foundation of China [11674154, 1171101156]
- Fundamental Research Funds for the Central Universities [020414380036, 020414380065]
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 (similar to 1.3 TPa) and 2D breaking strength of 43 N/m (similar to 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.
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