Li Mian, Lu Jun, Luo Kan, Li Youbing, Chang Keke, Chen Ke, Zhou Jie, Rosen Johanna, Hultman Lars, Eklund Per, Persson Per O Å, Du Shiyu, Chai Zhifang, Huang Zhengren, Huang Qing
Engineering Laboratory of Advanced Energy Materials , Ningbo Institute of Industrial Technology, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China.
Department of Physics, Chemistry, and Biology (IFM) , Linköping University , 58183 Linköping , Sweden.
J Am Chem Soc. 2019 Mar 20;141(11):4730-4737. doi: 10.1021/jacs.9b00574. Epub 2019 Mar 7.
Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesizing a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition-metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between the Zn element from molten ZnCl and the Al element in MAX phase precursors (TiAlC, TiAlC, TiAlN, and VAlC), novel MAX phases TiZnC, TiZnC, TiZnN, and VZnC were synthesized. When employing excess ZnCl, Cl-terminated MXenes (such as TiCCl and TiCCl) were derived by a subsequent exfoliation of TiZnC and TiZnC due to the strong Lewis acidity of molten ZnCl. These results indicate that A-site element replacement in traditional MAX phases by late transition-metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temperature and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addition, this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to preparing MXenes through an HF-free chemical approach.
纳米层状材料因其优异的性能和广泛的应用而备受关注。在此，我们展示了一种通用方法，用于合成一系列基于锌的MAX相和Cl端接的MXene，这些材料源自MAX相与后期过渡金属卤化物之间的置换反应。该方法是一种自上而下的途径，能够使后期过渡元素原子（在本文中为锌）占据预先存在的MAX相结构中的A位。利用熔融氯化锌中的锌元素与MAX相前驱体（TiAlC、TiAlC、TiAlN和VAlC）中的铝元素之间的这种置换反应，合成了新型MAX相TiZnC、TiZnC、TiZnN和VZnC。当使用过量的氯化锌时，由于熔融氯化锌的强路易斯酸性，通过随后对TiZnC和TiZnC进行剥离，得到了Cl端接的MXene（如TiCCl和TiCCl）。这些结果表明，后期过渡金属卤化物对传统MAX相中的A位元素进行置换为探索在高温下热力学不稳定且难以通过常用的粉末冶金方法合成的MAX相打开了大门。此外，这是首次获得仅含Cl端接的MXene，并且熔盐中路易斯酸的蚀刻作用为通过无HF化学方法制备MXene提供了一条绿色且可行的途径。
