Preparation of atomically thin 2D metals

Two-dimensional (2D) metals, which are appealing for a plethora of emergent phenomena and technological applications, stand as one of the highly sought-after goals in condensed-matter physics and materials science. In stark contrast to the widely-studied 2D van der Waals (vdW) layered materials in which their weak interlayer interactions facilitate the isolation from their bulk, 2D metals are extremely challenging to achieve because of their thermodynamic instability and non-layered nature. In this review, we highlight the recent advances in the reliable production of atomically thin 2D metals, including but not limited to vdW squeezing technique, top-down exfoliation, mechanical pressing, chemical etching, epitaxial growth, and confinement growth. We also present our perspectives and discuss the future opportunities and research directions in this new field.