Achieving structural superlubricity in graphitic samples of macroscale size is particularly challenging due to difficulties in sliding large contact areas of commensurate stacking domains. Here, we show the presence of macroscale structural superlubricity between two randomly stacked graphene layers produced by both mechanical exfoliation and chemical vapour deposition. By measuring the shifts of Raman peaks under strain we estimate the values of frictional interlayer shear stress (ILSS) in the superlubricity regime (mm scale) under ambient conditions. The random incommensurate stacking, the presence of wrinkles and the mismatch in the lattice constant between two graphene layers induced by the tensile strain differential are considered responsible for the facile shearing at the macroscale. Furthermore, molecular dynamic simulations show that the stick-slip behaviour does not hold for incommensurate chiral shearing directions for which the ILSS decreases substantially, supporting the experimental observations. Our results pave the way for overcoming several limitations in achieving macroscale superlubricity using graphene.

由于滑动相称堆叠域的大接触面积存在困难，在宏观尺寸的石墨样品中实现结构超润滑尤其具有挑战性。在这里，我们展示了通过机械剥离和化学气相沉积产生的两个随机堆叠的石墨烯层之间存在宏观结构超润滑性。通过测量应变下拉曼峰的位移，我们估计了环境条件下超润滑状态（毫米级）的摩擦层间剪切应力 (ILSS) 值。随机不相称的堆叠、皱纹的存在以及由拉伸应变差异引起的两个石墨烯层之间的晶格常数的不匹配被认为是宏观尺度上容易发生剪切的原因。此外，分子动力学模拟表明，粘滑行为并不适用于不相称的手性剪切方向，ILSS 会大幅下降，这支持了实验观察。我们的结果为克服使用石墨烯实现宏观超润滑的一些限制铺平了道路。