The Evolution of MXenes Conductivity and Optical Properties Upon Heating in Air
The Evolution of MXenes Conductivity and Optical Properties Upon Heating in Air
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DOI：
10.1002/smtd.202300568
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发表时间：
2023-07-16
期刊：
影响因子：
12.4
通讯作者：
Fakhraai, Zahra
中科院分区：
文献类型：
--
作者：
Shamsabadi, Ahmad A.;Fang, Hui;Fakhraai, Zahra
MXenes是一种二维过渡金属碳化物和氮化物，具有优异的导电性和独特的光学性能。然而，MXene在环境条件下氧化，这在加热时加速。水的嵌入也引起水解，加速氧化。开发新的工具来容易地表征MXene的热稳定性可以更深入地了解它们的结构-性质关系。在这里，在原位光谱椭圆偏振法（SE）是用来表征三种类型的MXene（Ti 3C 2 Tx，Mo 2 TiC 2 Tx，和Ti 2CTx）的光学性质与不同的组成和原子结构，以调查其热降解时，在周围环境下加热。它表明，在可见光和近红外区域中的MXene消光和光学电导率的变化与嵌入的水和羟基终止基团的量和氧化的程度，使用热重分析测量。在这三种MXene中，Ti 3C 2 Tx和Ti 2CTx分别具有最高和最低的热稳定性，表明过渡金属类型、合成路线和MXene薄片中原子层数目的作用。这些发现表明SE作为一种强大的原位技术用于快速结构-性能关系研究的实用性，为新型MXene材料的进一步设计，制造和性能优化铺平了道路。
MXenes, a family of 2D transition-metal carbides and nitrides, have excellent electrical conductivity and unique optical properties. However, MXenes oxidize in ambient conditions, which is accelerated upon heating. Intercalation of water also causes hydrolysis accelerating oxidation. Developing new tools to readily characterize MXenes' thermal stability can enable deeper insights into their structure-property relationships. Here, in situ spectroscopic ellipsometry (SE) is employed to characterize the optical properties of three types of MXenes (Ti3C2Tx, Mo2TiC2Tx, and Ti2CTx) with varied composition and atomistic structures to investigate their thermal degradation upon heating under ambient environment. It is demonstrated that changes in MXene extinction and optical conductivity in the visible and near-IR regions correlate well with the amount of intercalated water and hydroxyl termination groups and the degree of oxidation, measured using thermogravimetric analysis. Among the three MXenes, Ti3C2Tx and Ti2CTx, respectively, have the highest and lowest thermal stability, indicating the role of transition-metal type, synthesis route, and the number of atomic layers in MXene flakes. These findings demonstrate the utility of SE as a powerful in situ technique for rapid structure-property relationship studies paving the way for the further design, fabrication, and property optimization of novel MXene materials.