Wyatt Brian C, Boebinger Matthew G, Hood Zachary D, Adhikari Shiba, Michałowski Paweł Piotr, Nemani Srinivasa Kartik, Muraleedharan Murali Gopal, Bedford Annabelle, Highland Wyatt J, Kent Paul R C, Unocic Raymond R, Anasori Babak
Department of Mechanical & Energy Engineering, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Nat Commun. 2024 Jul 28;15(1):6353. doi: 10.1038/s41467-024-50713-2.
Transition metal carbides have been adopted in energy storage, conversion, and extreme environment applications. Advancements in their 2D counterparts, known as MXenes, enable the design of unique structures at the ~1 nm thickness scale. Alkali cations have been essential in MXenes manufacturing processing, storage, and applications, however, exact interactions of these cations with MXenes are not fully understood. In this study, using TiCT, MoTiCT, and MoTiCT MXenes, we present how transition metal vacancy sites are occupied by alkali cations, and their effect on MXene structure stabilization to control MXene's phase transition. We examine this behavior using in situ high-temperature x-ray diffraction and scanning transmission electron microscopy, ex situ techniques such as atomic-layer resolution secondary ion mass spectrometry, and density functional theory simulations. In MXenes, this represents an advance in fundamentals of cation interactions on their 2D basal planes for MXenes stabilization and applications. Broadly, this study demonstrates a potential new tool for ideal phase-property relationships of ceramics at the atomic scale.
过渡金属碳化物已被应用于能量存储、转换及极端环境应用中。其二维对应物（即MXenes）的发展，使得在约1纳米厚度尺度上设计独特结构成为可能。碱金属阳离子在MXenes的制造加工、存储及应用中至关重要，然而，这些阳离子与MXenes的确切相互作用尚未完全明确。在本研究中，我们使用TiCT、MoTiCT和MoTiCT MXenes，展示了过渡金属空位如何被碱金属阳离子占据，以及它们对MXene结构稳定性的影响，进而控制MXene的相变。我们使用原位高温X射线衍射和扫描透射电子显微镜、非原位技术（如原子层分辨率二次离子质谱）以及密度泛函理论模拟来研究这种行为。在MXenes中，这代表了阳离子在其二维基面相互作用的基础研究取得进展，有助于MXenes的稳定化及应用。总体而言，本研究展示了一种在原子尺度上建立陶瓷理想相-性能关系的潜在新工具。
