Metallic two-dimensional (2D) materials such as transition-metal dichalcogenides (TMDCs) and MXenes exhibit intriguing properties, including superconductivity, magnetism and electrocatalysis. Studies on the correlation between their nanoscale structures and properties can facilitate the development of photodetectors, supercapacitors, nanocatalysts, etc., but this topic has not been reviewed systematically. Here, we provide a comprehensive overview on the key factors that dictate the structures and properties of these 2D metals. We examine their phase transitions induced by structural or electronic modifications based on microscopic imaging, spectral characterization, and electrical measurements. From the perspective of surface and interface engineering, we elucidate the influences of lattice defects, dopants, and intercalated species between adjacent layers. Moreover, heterostructures involving highly conductive 2D component(s) are discussed, which may enable the observation of fascinating phenomena and/or synergistic effects due to the interlayer interactions. Finally, we provide insights into opportunities for new applications, e.g., radio-frequency antennas and electromagnetic interference shields. Feasible routes are also proposed to overcome the current challenges.

金属二维 (2D) 材料，如过渡金属二硫属化物 (TMDC) 和 MXenes，表现出有趣的特性，包括超导性、磁性和电催化。研究它们的纳米级结构与性能之间的相关性可以促进光电探测器、超级电容器、纳米催化剂等的发展，但该课题尚未得到系统的综述。在这里，我们全面概述了决定这些 2D 金属结构和特性的关键因素。我们基于显微成像、光谱表征和电气测量来检查它们由结构或电子修改引起的相变。我们从表面和界面工程的角度阐明了晶格缺陷、掺杂剂、和相邻层之间的插入物种。此外，还讨论了涉及高导电二维组件的异质结构，这可能有助于观察由于层间相互作用引起的迷人现象和/或协同效应。最后，我们提供了对新应用机会的见解，例如射频天线和电磁干扰屏蔽。还提出了可行的路线来克服当前的挑战。