Upscaled Synthesis Protocol for Phase-Pure, Colloidally Stable MXenes with Long Shelf Lives

Nick Goossens, Konstantina Lambrinou, Bensu Tunca, Vrushali Kotasthane, Miriam C. Rodríguez González, Anastasiia Basylevska, Per O.Å. Persson, Steven De Feyter, Miladin Radovic, Francisco Molina-Lopez, Jozef Vleugels

Research output: Contribution to journalArticlepeer-review

Abstract

MXenes are electrically conductive 2D transition metal carbides/nitrides obtained by the etching of nanolaminated MAX phase compounds, followed by exfoliation to single- or few-layered nanosheets. The mainstream chemical etching processes have evolved from pure hydrofluoric acid (HF) etching into the innovative “minimally intensive layer delamination” (MILD) route. Despite their current popularity and remarkable application potential, the scalability of MILD-produced MXenes remains unproven, excluding MXenes from industrial applications. This work proposes a “next-generation MILD” (NGMILD) synthesis protocol for phase-pure, colloidally stable MXenes that withstand long periods of dry storage. NGMILD incorporates the synergistic effects of a secondary salt, a richer lithium (Li) environment, and iterative alcohol-based washing to achieve high-purity MXenes, while improving etching efficiency, intercalation, and shelf life. Moreover, NGMILD comprises a sulfuric acid (H2SO4) post-treatment for the selective removal of the Li3AlF6 impurity that commonly persists in MILD-produced MXenes. This work demonstrates the upscaled NGMILD synthesis of (50 g) phase-pure Ti3C2Tz MXene clays with high extraction yields (>22%) of supernatant dispersions. Finally, NGMILD-produced MXene clays dry-stored for six months under ambient conditions experience minimal degradation, while retaining excellent redispersibility. Overall, the NGMILD protocol is a leap forward toward the industrial production of MXenes and their subsequent market deployment.

Original languageEnglish
Article number2300776
Number of pages14
JournalSmall Methods
Volume8
Issue number1
Early online date8 Oct 2023
DOIs
Publication statusPublished - 19 Jan 2024

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