Synthesis of Two-dimensional Metallic Nanosheets : From Elemental Metals to Chemically Complex Alloys

Ultrathin two-dimensional (2D) metallic materials with single- or few-atom thickness, emerging as one new class of 2D materials, have attracted extraordinary interest due to their fantastic physical and chemical properties, and great potential applications in catalysis, biomedicine, electronics/optoelectronic devices, sensing, and energy storage. In contrast with graphene-like 2D layered materials, facile fabrication of ultrathin 2D metallic materials remains a great challenge owing to their intrinsic tendency of metals to form three-dimensional (3D) close-packed structures. This article reviews and summarizes the recent progress-both experimental and theoretical- in the synthesis of 2D metallic nanosheets from mono-elemental metals to chemically complex alloys and offers perspectives and challenges on the future developments in this field.