Effect of surface morphology on friction of graphene on various substrates
Effect of surface morphology on friction of graphene on various substrates
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DOI：
10.1039/c3nr34181j
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发表时间：
2013-01-01
期刊：
影响因子：
6.7
通讯作者：
Lee, Changgu
中科院分区：
文献类型：
--
作者：
Cho, Dae-Hyun;Wang, Lei;Lee, Changgu
研究了石墨烯在SiO2、h-BN、块状石墨烯和云母等各种基底上的摩擦，以表征石墨烯与底层表面之间的粘附水平。石墨烯在SiO2上的摩擦力随着厚度的增加而减小，并由于两个表面之间的不完全接触而聚集在五层周围。然而，石墨烯在原子级平坦衬底（诸如h-BN或块状石墨烯）上的摩擦低并且与块状石墨烯的摩擦相当。相比之下，尽管体状石墨烯的超光滑度，但折叠到体状石墨烯上的石墨烯的摩擦与SiO2上的单层石墨烯的摩擦不可区分。折叠前后石墨烯的粗糙度的表征表明，即使在将石墨烯折叠到原子级平坦的衬底上之后，由SiO2形态诱导的石墨烯的粗糙度也得以保留。此外，沉积在云母上的石墨烯在折叠时保持与折叠事件之前相同的水平。我们的摩擦测量显示，石墨烯一旦从块状晶体剥离，即使在折叠到原子级平坦的衬底上之后，也倾向于保持其纳米级水平，并且需要石墨烯和衬底中的超平坦度来实现强粘附所需的紧密接触。
The friction of graphene on various substrates, such as SiO2, h-BN, bulk-like graphene, and mica, was investigated to characterize the adhesion level between graphene and the underlying surface. The friction of graphene on SiO2 decreased with increasing thickness and converged around the penta-layers due to incomplete contact between the two surfaces. However, the friction of graphene on an atomically flat substrate, such as h-BN or bulk-like graphene, was low and comparable to that of bulk-like graphene. In contrast, the friction of graphene folded onto bulk-like graphene was indistinguishable from that of mono-layer graphene on SiO2 despite the ultra-smoothness of bulk-like graphene. The characterization of the graphene's roughness before and after folding showed that the corrugation of graphene induced by SiO2 morphology was preserved even after it was folded onto an atomically flat substrate. In addition, graphene deposited on mica, when folded, preserved the same corrugation level as before the folding event. Our friction measurements revealed that graphene, once exfoliated from the bulk crystal, tends to maintain its corrugation level even after it is folded onto an atomically flat substrate and that ultra-flatness in both graphene and the substrate is required to achieve the intimate contact necessary for strong adhesion.