Ultrasonic-Ball Milling: A Novel Strategy to Prepare Large-Size Ultrathin 2D Materials.

Large-size ultrathin 2D materials, with extensive applications in optics, medicine, biology, and semiconductor fields, can be prepared through an existing common physical and chemical process. However, the current exfoliation technologies still need to be improved upon with urgency. Herein, a novel and simple "ultrasonic-ball milling" strategy is reported to effectively obtain high quality and large size ultrathin 2D materials with complete lattice structure through the introduction of moderate sapphire (Al2 O3 ) abrasives in a liquid phase system. Ultimately numerous high-quality ultrathin h-BN, graphene, MoS2 , WS2 , and BCN nanosheets are obtained with large sizes ranging from 1-20 µm, small thickness of ≈1-3 nm and a high yield of over 20%. Utilizing shear and friction force synergistically, this strategy provides a new method and alternative for preparing and optimizing large size ultrathin 2D materials.