Electrochemical exfoliation of graphene-like two-dimensional nanomaterials

Unlike zero-dimensional quantum dots, one-dimensional nanowires/nanorods, and three-dimensional networks or even their bulk counterparts, the charge carriers in two-dimensional (2D) materials are confined along the thickness while being allowed to move along the plane. They have distinct characteristics like strong quantum confinement, tunable thickness, and high specific surface area, which makes them a promising candidate in a wide range of applications such as electronics, topological spintronic devices, energy storage, energy conversion, sensors, biomedicine, catalysis, and so on. After the discovery of the extraordinary properties of graphene, other graphene-like 2D materials have attracted a great deal of attention. Like graphene, to realize their potential applications, high efficiency and low cost industrial scale methods should be developed to produce high-quality 2D materials. The electrochemical methods usually performed under mild conditions are convenient, controllable, and suitable for mass production. In this review, we introduce the latest and most representative investigations on the fabrication of 2D monoelemental Xenes, 2D transition-metal dichalcogenides, and other important emerging 2D materials such as organic framework (MOF) nanosheets and MXenes through electrochemical exfoliation. The electrochemical exfoliation conditions of the bulk layered materials are discussed. The numerous factors which will affect the quality of the exfoliated 2D materials, the possible exfoliating mechanism and potential applications are summarized and discussed in detail. A summary of the discussion together with perspectives and challenges for the future of this emerging field is also provided in the last section.