Ultrastrong isotropic graphene sheets by nanoconfined strategy
Conventional assembly of two-dimensional nanoplatelets into layered nanocomposites via wet chemical methods suffers from capillary contraction during water evaporation, inducing wrinkles, voids, and reduced orientation, leading to subpar mechanical performance. Here, we highlight a nanoconfined strategy developed by Prof. Qunfeng Cheng and Prof. Ray H. Baughman that eliminates capillary contraction by confining atomically thin water layers between graphene oxide (GO) and MXene nanoplatelets during continuous vacuum filtration. This process yields highly aligned, in-plane isotropic MXene-bridged GO (MGO) sheets. Subsequent reduction with hydriodic acid and cross-linking with a π-bridging agent (PSE-AP) in solution produces MXene-bridged graphene (πBMG) sheets with exceptional mechanical properties: tensile strength of 1870 ± 20 MPa and Young's modulus of 98.7 ± 1.1 GPa, surpassing previous graphene, MXene, and graphene-MXene sheets as well as carbon fiber-fabric composites. The superior alignment and strong interfacial interactions enable efficient stress transfer. This work introduces a new concept of nanoconfined water-induced alignment, achieving true in-plane isotropy without sacrificing other performance, and opens a new avenue for assembling high-performance layered nanocomposites from various 2D nanoplatelets.