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Ambient Oxidation of Ti3C2 MXene Initialized by Atomic Defects

Abstract

MXenes are a group of two-dimensional transition metal carbides/nitrides that have been widely used for many useful applications such as energy storage, catalysis and sensors. For large scale applications of MXenes, the ambient stability is a critical issue. However, the detailed degradation mechanism of MXenes remains largely unclear. Here, the oxidation mechanism of MXene flakes at ambient conditions has been studied using aberration corrected scanning transmission electron microscopy (STEM). Heterogeneous growth of titanium oxide has been observed in the vicinity of atomic defects on the MXene basal plane as well as on edges of MXenes flakes. C atoms are oxidized at locations of Ti-vacancies to form amorphous carbon aggregations, while Ti cations are oxidized at the nearby sites with atomic steps/edges. Diffusion of both electrons and Ti cations is involved and the Ti-ion diffusion is prompt by an internal electric field intrinsically built up during oxidation. The anatase TiO2 nanoparticles are preferentially growing along the {101} lattice plane. A loose orientation relationship between the anatase TiO2 and MXene was identified, showing that mostly the {101} plane of TiO2 nanocrystals is perpendicular to the Ti3C2-MXene {0001} basal plane. This work reveals at atomic resolution the oxidation mechanism of MXenes at ambient conditions and will shed lights on the design and synthesis of more stable MXenes. It may also provide insights to develop a one-step method to synthesize hybrid structures of carbon supported TiO2 nanoparticles for future large scale applications.

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Supplementary files

Publication details

The article was received on 22 Aug 2019, accepted on 06 Nov 2019 and first published on 07 Nov 2019


Article type: Paper
DOI: 10.1039/C9NR07236E
Nanoscale, 2019, Accepted Manuscript

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    Ambient Oxidation of Ti3C2 MXene Initialized by Atomic Defects

    F. Xia, L. junchao, R. Yu, X. Sang, J. Luo, Y. Li and J. wu, Nanoscale, 2019, Accepted Manuscript , DOI: 10.1039/C9NR07236E

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