University of Oulu

Ibragimova, R., Rinke, P., & Komsa, H.-P. (2022). Native vacancy defects in mxenes at etching conditions. Chemistry of Materials, 34(7), 2896–2906.

Native vacancy defects in MXenes at etching conditions

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Author: Ibragimova, Rina1,2; Rinke, Patrick1; Komsa, Hannu-Pekka1,3
Organizations: 1Department of Applied Physics, Aalto University, P.O. Box 11100, 00076 Aalto, Finland
2Department of Electrical Engineering and Automation, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
3Microelectronics Research Unit, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.6 MB)
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Language: English
Published: American Chemical Society, 2022
Publish Date: 2022-10-21


Two-dimensional MXenes have recently received increased attention due to their facile synthesis process and extraordinary properties suitable for many different applications. During the wet etching synthesis of MXenes, native defects, such as metal and carbon or nitrogen vacancies, are produced, but the underlying defect formation processes are poorly understood. Here, we employ first-principles calculations to evaluate formation energies of Ti, C, and N vacancies in Ti3C2 and Ti2N MXenes under etching conditions. We carefully account for the mixed functionalization of the surfaces as well as the chemical environment in the solution (pH and electrode potential). We observe that the formation energies of the metal vacancies differ significantly for different types of surface functionalization as well as for different local and global environments. We attribute these differences to electrostatic interactions between vacancies and the surrounding functional groups. We predict that Ti vacancies will be prevalent on bare or OH-functionalized surfaces but not on O-functionalized ones. In contrast, C and N vacancies are more prevalent in O-functionalized surfaces. In addition, our results suggest that the pH value of the etching solution and the electrode potential strongly affect vacancy formation. In particular, the predicted conditions at which abundant vacancy formation is expected are compared to experiments and found to coincide with conditions at which MXenes oxidize readily. This suggests that Ti vacancy formation is a crucial step in initiating the oxidation process.

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Series: Chemistry of materials
ISSN: 0897-4756
ISSN-E: 1520-5002
ISSN-L: 0897-4756
Volume: 34
Issue: 7
Pages: 2896 - 2906
DOI: 10.1021/acs.chemmater.1c03179
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: We acknowledge funding from the Academy of Finland under Project No. 311058. We gratefully acknowledge CSC – IT Center for Science, Finland, and the Aalto Science-IT project for generous computational resources.
Dataset Reference: The Supporting Information is available free of charge at
Copyright information: © 2022 The Authors. This is an Open Access article under the CC BY 4.0 license.