Hydrolysis of 2D Transition-Metal Carbides (MXenes) in Colloidal Solutions

Abstract

Although oxidation was deemed as the main factor responsible for the instability of MXenes in aqueous colloids, here we put forward and test a hypothesis about the central role of water as the primary factor. We show that water and related processes of MXene hydrolysis play the main role in the phenomena leading to complete transformations of 2D titanium carbide MXenes into titania in aqueous environments. To demonstrate the role of water, the stability of two MXenes, Ti3C2Tx and Ti2CTx, has been systematically studied in aqueous and nonaqueous colloids exposed to oxygen and inert gas atmospheres. The calculated time constant for degradation of Ti3C2Tx dispersed in anhydrous iso-propanol saturated with pure oxygen exceeds 5 years, in striking contrast to the same MXene dispersed in water, where more than a half of it would transform into titania even in an oxygen-less atmosphere over ∼41 days. A thinner Ti2CTx MXene showed similar behavior, albeit with shorter time constants in both solvents, correspondingly. UV-vis and Raman spectroscopy were used to analyze the oxidation kinetics and composition of fresh and aged MXenes. An intense anatase peak was observed in MXenes stored in aqueous solutions under Ar atmosphere, while no signs of oxidation could be found in iso-propanol solutions of the MXenes stored under O2 atmosphere over a similar period of time.

Department(s)

Chemistry

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Carbides; Transition metals; Metal carbides

International Standard Serial Number (ISSN)

0020-1669; 1520-510X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2019 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Feb 2019

PubMed ID

30649863

Link to Full Text

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