Two-dimensional (2D) layered materials such as graphene, hexagonal boron nitride, molybdenum disulfide and alike possess unique frictional properties, making them promising candidates as (additives to) lubricants for friction reduction and wear protection, especially in micro- and nano-electromechanical systems. To truly apply these materials, it is essential to understand friction at the nanoscale level. In recent decades, with the development of atomic and friction force microscopy and atomistic simulation tools, our understanding of the friction of 2D materials has substantially increased. Herein, we summarize the essential friction behaviors of 2D materials as well as the underlying physical mechanisms explored by friction force microscopy. In particular, the effects of atomic structures and external factors on friction, and the strategies to realize the modulation of friction are discussed. Finally, the challenges in practical applications of 2D materials as atomically thin lubricants and the perspectives for future progression are provided.

二维 (2D) 层状材料，如石墨烯、六方氮化硼、二硫化钼等，具有独特的摩擦特性，使其成为减少摩擦和磨损保护的润滑剂（添加剂）的有希望的候选者，特别是在微纳机电系统。要真正应用这些材料，必须了解纳米级的摩擦。近几十年来，随着原子和摩擦力显微镜和原子模拟工具的发展，我们对二维材料摩擦的理解有了很大的提高。在这里，我们总结了二维材料的基本摩擦行为以及摩擦力显微镜探索的潜在物理机制。特别是原子结构和外部因素对摩擦的影响，讨论了实现摩擦调制的策略。最后，提供了二维材料作为原子薄润滑剂在实际应用中的挑战以及未来发展的前景。