How Much Oxygen Can a MXene Surface Take Before It Breaks?. (18th February 2020)

• Record Type: Journal Article
• Authors: Persson, Ingemar; Halim, Joseph; Hansen, Thomas W.; Wagner, Jakob B.; Darakchieva, Vanya; Palisaitis, Justinas; Rosen, Johanna; Persson, Per O. Å.
• Is Part Of: Advanced functional materials. Volume 30:Number 47(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-18
• Subjects: 2D materials -- environmental TEM -- MXene -- surface terminations; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201909005
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Tuning and tailoring of surface terminating functional species hold the key to unlock unprecedented properties for a wide range of applications of the largest 2D family known as MXenes. However, a few routes for surface tailoring are explored and little is known about the extent to which the terminating species can saturate the MXene surfaces. Among available terminations, atomic oxygen is of interest for electrochemical energy storage, hydrogen evolution reaction, photocatalysis, etc. However, controlled oxidation of the surfaces is not trivial due to the favored formation of oxides. In the present contribution, single sheets of Ti3 C2 T x MXene, inherently terminated by F and O, are defluorinated by heating in vacuum and subsequentially exposed to O2 gas at temperatures up to 450 °C in situ, in an environmental transmission electron microscope. Results include exclusive termination by O on the MXene surfaces and eventual supersaturation ( x > 2) with a retained MXene sheet structure. Upon extended O exposure, the MXene structure transforms into TiO2 and desorbs surface bound H2 O and CO2 reaction products. These results are fundamental for understanding the oxidation, the presence of water on MXene surfaces, and the degradation of MXenes, and pave way for further tailoring of MXene surfaces. Abstract : The surface functionalization of 2D materials is critical for tuning properties and application performance. In the case of MXenes, oxygen‐terminated surfaces are critical for applications in energy storage and catalysis. Here, a route for exclusively functionalizing MXene surfaced by oxygen is shown and pushed to the limit.