Electrochemical exfoliation of two-dimensional layered black phosphorus and applications

With the discovery of graphene, black phosphorus(BP) has been rediscovered as a two-dimensional(2 D) layered material. Since its first preparation in 2014, 2 D BP has elicited immense interest, and has exhibited excellent properties, such as distinct pleated structures in layers, adjustable direct bandgap,high carrier mobility, moderate on/off ratio, large specific surface area, and various interesting in-layer anisotropies. However, the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets. Electrochemical exfoliation methods are typically performed under mild conditions,thus, these methods are convenient, controllable, and can produce high-quality 2 D BP sheets. This review summarizes research progress in BP sheets preparation through anodic, cathodic, and electrolyte exfoliation in recent years. Different exfoliating methods affect the quality of 2 D BP sheets. Moreover, possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail. Lastly, the shortcomings of existing research on electrochemical exfoliation are presented, and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.