Two-dimensional materials (2D) are the thinnest functional nanomaterials, due to their atomic scale thickness and infinite planar dimensions. They are characterized by strong in-plane chemical bonds and weak interlayer bonds. 1 By means of micromechanical2 or chemical3 exfoliation techniques, it is possible to isolate a few or single freestanding nanosheets, which can be used as atomically thick membranes or, alternatively, as nanofillers in polymeric membranes, thus yielding novel functionalities. The existence of a large and chemically active surface area in nanoporous 2D materials inside composite membranes may significantly improve their transport properties. The recent achievements of membrane technology in different fields, from water desalination4, 5 to gas separation, 6, 7 are based on research