Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenes

Kamysbayev, Vladislav; Filatov, Alexander S.; Hu, Huicheng; Xue, Rui; Lagunas, Francisco; Wang, Di; Klie, Robert F.; Talapin, Dmitri V.

doi:10.1126/science.aba8311

Cited by 1,084 publications

(1,027 citation statements)

References 59 publications

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“…What is more, the molten Lewis acidic salts etching method introduces some new terminations on MXenes, such as Cl and Br, opening up a new design space for the surface group regulation. Talapin et al [59] show that Cl-and, especially, Br-terminated MXenes can efficiently engage in a new type of surface reactions where halide ions exchange for other atoms and functional groups. Based on this, they proposed a general strategy by performing substitution and elimination reactions in molten inorganic salts to achieve the installation and removing of surface groups in MXenes, successfully synthesizing MXenes with O, NH, S, Cl, Se, Br, and Te surface terminations, as well as bare MXenes.…”

Section: Targeted Surface Terminations Regulationmentioning

confidence: 99%

Interface Chemistry on MXene‐Based Materials for Enhanced Energy Storage and Conversion Performance

Hui

Zhao

et al. 2020

Adv Funct Materials

175

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MXenes have attracted increasing attention due to their unique advantages, excellent electronic conductivity, tunable layer structure, and controllable interfacial chemistry. However, the practical applications of MXenes in energy storage devices are severely limited by the issues of torpid reaction kinetics, limited active sites, and poor material utilization efficiency. Herein, the most-up-to date advances in the rational microstructure design to enhance electrochemical reaction kinetics and energy storage performance of MXene-based materials are comprehensively summarized. This review begins with the preparation and properties of MXenes, classified into fluorine-containing acid etching and fluoride-free etching approaches. Afterwards, the interlayer structure design and interfacial functionalization of MXenes with respect to interlayer spacing and porous structure, terminal groups, and surface defects are summarized. Then the focus turns to the construction of advanced MXene-based heterojunctions based on in situ derivation and surface self-assembly. Based on these microstructure modulating strategies, the state-of-the-art progress of MXene-based applications with respect to supercapacitors, alkali metal-ion batteries, metal-sulfur batteries, and photo/electrocatalysis are highlighted. Finally, the critical challenges and perspectives for the future research of 2D MXene-based nanostructures are highlighted, aiming to present a comprehensive reference for the design of MXene-based electrodes for electrochemical energy storage.

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Section: Targeted Surface Terminations Regulationmentioning

confidence: 99%

Interface Chemistry on MXene‐Based Materials for Enhanced Energy Storage and Conversion Performance

Hui

Zhao

et al. 2020

Adv Funct Materials

175

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“…Altogether, such trends are valid rules-of-thumb so as to forecast future chemical activities on pristine MXenes or interpret results. This becomes particularly important given the recent experimental reports on cleaning protocols for terminated MXenes [12] and the novel synthetic routes capable of generating surface pristine MXenes [33].…”

Section: Resultsmentioning

confidence: 99%

Exfoliation Energy as a Descriptor of MXenes Synthesizability and Surface Chemical Activity

Dolz¹,

Morales‐García²,

Viñes³

et al. 2020

Preprint

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MXenes are two-dimensional nanomaterials isolated from MAX phases by the selective extraction of the A component —a p-block element. The MAX phase exfoliation energy, Eexf, is regarded as a chemical descriptor of the MXene synthesizability. Here we show, by density functional theory estimations of the Eexf values for 486 different MAX phases, that Eexf decreases i) when MAX is a nitride, ii) when going along a d series of the metal M component, iii) when going down a group of the p-block A element, as well as iv) when having thicker MXene phases. Furthermore, Eexf is found to bias, even to govern, the surface chemical activity, as evaluated here on the CO2 adsorption strength, so that more unstable MXenes, displaying larger Eexf values, display a stronger attachment of species upon.

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“…The molten salts method has shown great ability to control and change the functional groups. [43][44][45] However, much more efforts are required to explore more facile approaches to synthesize MXenes with controllable terminations, especially those Figure 19. Schematic illustration of the various strategies that can be used to exploit MXenes to improve the performance of emerging batteries (beyond the Li ion).…”

Section: Conclusion and Perspectivementioning

confidence: 99%

MXenes for Rechargeable Batteries Beyond the Lithium‐Ion

et al. 2020

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past few decades. [2] In spite of the great success of the LIBs in consumer electronics and electric vehicles, their gridscale implementation is hindered by the limited lithium resources (only 20 ppm in the earth's crust) as well as the safety concerns. [3] In this regard, many other EES systems based on more abundant and less active elements, such as sodium (2.3%), potassium (2.1%), magnesium (2.3%), aluminum (8.2%), and zinc (75 ppm), have been developed and have already achieved significant progress. [1d,4] Historically, 2D layered materials have been employed as electrodes for batteries (e.g., graphite, [5] LiCoO 2 , [6] and TiS 2 [7]). Since the discovery of monolayer graphene in 2004, [8] more and more emerging 2D materials have quickly become popular electrode materials for various EES devices. This is not surprising given the unique structure and property of 2D materials. Their relatively large interlayer space allows fast ion (de)intercalation, whereas the highly anisotropic 2D structure enables fast charge transfer. Recently, a new class of 2D transition metal carbides, nitrides, and carbonitrides, known as MXenes, [9] was discovered and has attracted increasing research interest. Up to date, more than 30 MXenes have been successfully synthesized. [10] Similar to other 2D layered materials, MXenes also possess large/tunable interlayer spaces and high aspect ratios. In addition, MXenes show excellent hydrophilicity (contact angle is ≈21.5°-35°) [11] and extraordinary conductivity (e.g., ≈9880 S cm −1 for Ti 3 C 2 T x , 3250 ± 100 S cm −1 for V 2 CT x). [12] Further, MXenes are coupled with various terminations (e.g., OH, O, and F), which endow rich surface chemistries. These unique properties make them appealing in various applications, especially for energy storage devices such as batteries and supercapacitors. [1d,4i,13] We noted that there have already been several excellent reviews on the application of MXenes for energy storage and conversion, which cover a wide range of topics including for LIBs, supercapacitors, electrocatalysis, photocatalysis, electromagnetic interference, and so on. [10a,14] However, a more specific summary focuses on the rechargeable batteries is required and beneficial for the researchers working on nextgeneration batteries. Moreover, the study and investigation on MXenes for other EES systems beyond LIB are rapidly developing and have achieved great progress very recently. For example, great research efforts have been invested in exploring the application of MXenes in Li-sulfur batteries Research on next-generation battery technologies (beyond Li-ion batteries, or LIBs) has been accelerating over the past few years. A key challenge for these emerging batteries has been the lack of suitable electrode materials, which severely limits their further developments. MXenes, a new class of 2D transition metal carbides, carbonitrides, and nitrides, are proposed as electrode materials for these emerging batteries due to several desirable attributes. These attributes include large a...

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Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenes

Cited by 1,084 publications

References 59 publications

Interface Chemistry on MXene‐Based Materials for Enhanced Energy Storage and Conversion Performance

Interface Chemistry on MXene‐Based Materials for Enhanced Energy Storage and Conversion Performance

Exfoliation Energy as a Descriptor of MXenes Synthesizability and Surface Chemical Activity

MXenes for Rechargeable Batteries Beyond the Lithium‐Ion

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