We report the superlubric sliding of monolayer tungsten disulfide (WS₂) on epitaxial graphene (EG) grown on silicon carbide (SiC). Single-crystalline WS₂ flakes with lateral size of hundreds of nanometers are obtained via chemical vapor deposition (CVD) on EG. Microscopic and diffraction analyses indicate that the WS₂/EG stack is predominantly aligned with zero azimuthal rotation. The present experiments show that, when perturbed by a scanning probe microscopy (SPM) tip, the WS₂ flakes are prone to slide over the graphene surfaces at room temperature. Atomistic force field-based molecular dynamics simulations indicate that, through local physical deformation of the WS₂ flake, the scanning tip releases enough energy to the flake to overcome the motion activation barrier and trigger an ultralow-friction rototranslational displacement, that is superlubric. Experimental observations show that, after sliding, the WS₂ flakes come to rest with a rotation of nπ/3 with respect to graphene. Moreover, atomically resolved measurements show that the interface is atomically sharp and the WS₂ lattice is strain-free. These results help to shed light on nanotribological phenomena in van der Waals (vdW) heterostacks, and suggest that the applicative potential of the WS₂/graphene heterostructure can be extended by novel mechanical prospects.

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我们报告了在碳化硅（SiC）上生长的外延石墨烯（EG）上单层二硫化钨（WS ₂）的超润滑滑动。通过在EG上的化学气相沉积（CVD）获得横向尺寸为数百纳米的单晶WS ₂薄片。显微镜和衍射分析表明，WS ₂ / EG堆栈主要与零方位角旋转对齐。本实验表明，当受到扫描探针显微镜（SPM）尖端的干扰时，WS ₂薄片在室温下易于在石墨烯表面上滑动。基于原子力场的分子动力学模拟表明，通过WS _2的局部物理变形薄片时，扫描尖端会向薄片释放足够的能量，从而克服运动激活障碍并触发超低摩擦的旋转位移，即超级润滑。实验观察表明，滑动之后，WS ₂薄片配备的旋转休息Ñ π/ 3相对于石墨烯。此外，原子分辨的测量结果表明界面原子上很清晰，并且WS ₂晶格没有应变。这些结果有助于阐明范德华（vdW）异质堆栈中的纳米摩擦学现象，并表明WS ₂ /石墨烯异质结构的应用潜力可以通过新颖的机械前景来扩展。

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