Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
ACS Nano. 2017 Feb 28;11(2):2180-2186. doi: 10.1021/acsnano.6b08534. Epub 2017 Feb 13.
Two-dimensional (2D) transition-metal nitrides just recently entered the research arena, but already offer a potential for high-rate energy storage, which is needed for portable/wearable electronics and many other applications. However, a lack of efficient and high-yield synthesis methods for 2D metal nitrides has been a major bottleneck for the manufacturing of those potentially very important materials, and only MoN, TiN, and GaN have been reported so far. Here we report a scalable method that uses reduction of 2D hexagonal oxides in ammonia to produce 2D nitrides, such as MoN. MoN nanosheets with subnanometer thickness have been studied in depth. Both theoretical calculation and experiments demonstrate the metallic nature of 2D MoN. The hydrophilic restacked 2D MoN film exhibits a very high volumetric capacitance of 928 F cm in sulfuric acid electrolyte with an excellent rate performance. We expect that the synthesis of metallic 2D MoN and two other nitrides (WN and VN) demonstrated here will provide an efficient way to expand the family of 2D materials and add many members with attractive properties.
二维（2D）过渡金属氮化物最近才进入研究领域，但已经具有高倍率储能的潜力，这是便携式/可穿戴电子设备和许多其他应用所需要的。然而，缺乏高效、高产的 2D 金属氮化物合成方法一直是制造这些潜在的非常重要材料的主要瓶颈，迄今为止仅报道了 MoN、TiN 和 GaN。在这里，我们报告了一种可扩展的方法，该方法使用氨还原二维六方氧化物来制备二维氮化物，例如 MoN。我们对具有亚纳米厚度的 MoN 纳米片进行了深入研究。理论计算和实验都证明了二维 MoN 的金属性质。亲水性再堆叠的二维 MoN 薄膜在硫酸电解质中表现出非常高的体积电容，为 928 F cm，具有出色的倍率性能。我们预计，这里展示的金属 2D MoN 和另外两种氮化物（WN 和 VN）的合成将为扩展二维材料家族并添加许多具有吸引力的特性的成员提供有效的途径。
