- Titel
- Controllable Synthesis of MXenes with Novel and Ordered Terminations
- Zitierfähige Url:
- https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-943988
- Erstveröffentlichung
- 2024
- Datum der Einreichung
- 16.07.2024
- Datum der Verteidigung
- 22.10.2024
- Abstract (EN)
- Two-dimensional (2D) transition metal carbides/nitrides, known as MXenes, have captured intensive attention owing to their promising applications in the areas of energy storage, (opto)electronics, environment, etc. However, the structures of MXenes reported to date mostly exhibit disordered surface terminations, which hinder the understanding of MXene properties, largely due to the limitations of synthetic methods. Recent research has underscored the pivotal role of surface terminations in shaping the intrinsic properties of MXenes. Therefore, this study primarily focuses on establishing new synthesis methods to produce MXenes with novel and ordered surface terminations. We first develop a eutectic molten salt synthesis strategy to obtain MXenes. Characterizations confirm that the synthesized MXenes exhibit ordered surface terminations composed of three layers of atoms in an 'O-B-O' arrangement. Contrasting with conventional Cl/O-terminated Nb2C with localized charge transport, OBO-terminated Nb2C features band transport described by the Drude model. Consequently, it results in notable 15-fold and tenfold enhancement in electrical conductivity and charge mobility, respectively. Furthermore, OBO-terminated Ti3C2 achieves a high Li+ storage capacity (420 mAh g−1), double that of Cl/O-terminated Ti3C2. Subsequently, we develop a triphasic reaction involving gas-liquid-solid (GLS) to obtain MXenes with impurity-free and controllably orchestrated halogen terminations (Cl, Br I or their mixture). This GLS method is experimentally demonstrated to show universality and controllability for MXene production (GLS-MXenes). Characterizations reveal that GLS-MXenes exhibit uniform halogen terminations, representing an ordered surface structure. Compared to ClO-Ti3C2 with mixed Cl-/O-terminations, GLS-Ti3C2Cl2 exhibits a 160-fold improvement in macroscopic charge transport and a 163-fold enhancement in photoconductivity. This improvement is attributed to uncontaminated Cl-terminations with high structural ordering, effectively mitigating strong electron trapping and backscattering. Lastly, GLS synthesis demonstrates the capability to controllably orchestrate terminations of MXenes with dual-halogen and triple-halogen terminations. Finally, we also validate the feasibility of using a post-conversion strategy to alter the terminations on MXene surfaces. By employing MXenes with I-terminations as precursors, the termination can be replaced to chalcogen elements (S, Se) or organic molecules (acetate, methylbenzylamine, thiol) using gas-phase or liquid-phase reactions. Our research contributes to the further expansion of 2D MXene family and paves the way for the controlled synthesis of MXenes and the construction of ordered surface structures on MXenes, as well as the potential to control the properties of MXenes in (opto)electronics and energy storage by tailoring the terminations.
- Verweis
- Link: https://www.nature.com/articles/s41563-024-01911-2
MXenes with ordered triatomic-layer borate polyanion terminations
DOI: 10.1038/s41563-024-01911-2 - Band transport by large Fröhlich polarons in MXenes
DOI: 10.1038/s41567-022-01541-y - Freie Schlagwörter (EN)
- MXenes, 2D Materials, energy storage, charge transport
- Klassifikation (DDC)
- 540
- Klassifikation (RVK)
- VH 5507
- GutachterIn
- Prof. Dr. Xinliang Feng
- Prof. Dr. Ehrenfried Zschech
- BetreuerIn Hochschule / Universität
- Prof. Dr. Xinliang Feng
- Den akademischen Grad verleihende / prüfende Institution
- Technische Universität Dresden, Dresden
- Version / Begutachtungsstatus
- publizierte Version / Verlagsversion
- URN Qucosa
- urn:nbn:de:bsz:14-qucosa2-943988
- Veröffentlichungsdatum Qucosa
- 12.12.2024
- Dokumenttyp
- Dissertation
- Sprache des Dokumentes
- Englisch
- Lizenz / Rechtehinweis
CC BY-NC-ND 4.0- Inhaltsverzeichnis
Abstract V List of Figures XI List of Tables XIII 1 Chapter 1: Introduction and background 2 1.1 Overview of 2D transition metal and carbide/nitride (MXene) 2 1.1.1 Structure of MXenes 3 1.1.2 Properties and applications of MXene 6 1.2 Synthesis of MXenes 12 1.2.1 Top-down synthesis 12 1.2.2 Bottom-up synthesis 16 1.2.3 Challenges on MXenes synthesis 18 1.3 Surface chemistry of MXenes 19 1.3.1 The synthesis and types of terminations 20 1.3.2 The significant effect of terminations 23 1.3.3 Challenges on the surface chemistry of MXenes 27 1.4 Motivations and aims 28 1.5 References 32 2 Chapter 2: MXenes with Ordered Triatomic-Layer Borate Polyanion Terminations 38 2.1 Introduction 38 2.2 Methods 39 2.2.1 Chemicals 39 2.2.2 Synthesis of OBO-MXenes 40 2.2.3 Materials Characterizations 40 2.2.4 Charge transport properties measurements 42 2.2.5 Electrochemical property measurements 43 2.2.6 Computational studies 44 2.3 Results and discussion 44 2.3.1 Synthesis and structure of OBO-terminated MXenes 44 2.3.2 Atomic configuration of OBO-terminations 50 2.3.3 Charge-transport properties 54 2.3.4 Ultrahigh Li+-hosting capacity 60 2.3.5 Conclusion 66 2.4 References 67 3 Chapter 3: Triphasic synthesis of MXenes with impurity-free and controllably orchestrated halogen terminations 70 3.1 Introduction 70 3.2 Methods 72 3.2.1 Chemicals 72 3.2.2 Synthesis of GLS-MXenes 72 3.2.3 Materials Characterizations 73 3.2.4 Charge transport properties measurements 74 3.2.5 Computational studies 75 3.3 Results and discussion 76 3.3.1 Synthesis of MXenes with mono-halogen terminations 76 3.3.2 Structural analysis of MXenes 81 3.3.3 Terminations with high purity 85 3.3.4 Significance of impurity-free halogen terminations 87 3.3.5 Synthesis of MXenes with controllably orchestrated halogen terminations 90 3.3.6 Conclusion 92 3.4 References 93 4 Chapter 4: Post-conversion reactions for MXene termination substitution 96 4.1 Introduction 96 4.2 Chemicals 97 4.2.1 Synthesis 97 4.2.2 Materials Characterizations 98 4.3 Results and discussion 98 4.3.1 Post-conversion to synthesize chalcogen terminations 98 4.3.2 Structure of chalcogen-terminated MXenes 100 4.3.3 Post-conversion to synthesize organic terminations 102 4.3.4 Structures of organic-terminated MXenes 103 4.3.5 Conclusion 106 4.4 References 107 5 Summary and outlook 108 5.1 Summary 108 5.2 Outlook 109 5.3 References 112 Acknowledgment 114 Versicherung 116 Attachment: publications