NMR reveals the surface functionalisation of Ti<sub>3</sub>C<sub>2</sub>MXene

Hope, Michael A.; Forse, Alexander C.; Griffith, Kent J.; Lukatskaya, Maria R.; Ghidiu, Michael; Gogotsi, Yury; Grey, Clare P.

doi:10.1039/c6cp00330c

Cited by 802 publications

(659 citation statements)

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“…MXenes are a new class of 2D transition metal carbides and nitrides with chemical formula of M n+1 X n (M= Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta; X= C, N) with n = 1, 2, 3 that have recently been synthesized through hydrofluoric etching [40,41] of layered MAX phase compounds−M n+1 AX n , where A = Al, Si, P, S, Ga, Ge, As, In, and Sn [42,43]. During the etching process, the A element is washed out from the MAX phase structure and simultaneously the surfaces of the resulting 2D systems are chemically saturated with mixture of F, O, and OH [40,41,44,45]. These 2D systems have been named MXenes because they originate from the MAX phases by removing A elements and because they are structurally analogous to the graphene [40,41].…”

Section: Introductionmentioning

confidence: 99%

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

et al. 2016

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The family of two-dimensional transition metal carbides, so called MXenes, has recently found new members with ordered double transition metals M ′ 2 M ′′ C 2 , where M ′ and M ′′ stand for transition metals. Here, using a set of first-principles calculations, we demonstrate that some of the newly added members, oxide M ′ and M ′′ , while the band inversion occurs at the Γ point among the degenerate d x 2 −y 2 /d xy orbitals and a non-degenerate d 3z 2 −r 2 orbital, which is driven by the hybridization of the neighboring orbitals. The phonon dispersion calculations find that the predicted topological insulators are structurally stable. The predicted W-based MXenes with large band gaps might be suitable candidates for many topological applications at room temperature. In addition, we study the electronic structures of thicker ordered double transition metals M Zr, Hf) and find that they are nontrivial topological semimetals. Among the predicted topological insulators and topological semimetals, Mo 2 TiC 2 and Mo 2 Ti 2 C 3 functionalized with mixture of F, O, and OH have already been synthesized, and therefore some of the topological materials proposed here can be experimentally accessed.

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Section: Introductionmentioning

confidence: 99%

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

et al. 2016

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“…As with other 2D nanomaterials such as graphene, an increase in functionality is considered to be due to the larger lateral surface area, and the extent/type of functional surface termination groups. 10,11 Since the first report by Naguib et al Figure 2e) and more apparently in TEM images (Figure 3d), is a consistent circular cavity in the spherical MXene structures, averaging less than 1µm in diameter. The formation of MXene spheres appears to be unprecedented.…”

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“…Selective chemical etching out the A layer from the MAX phase, typically using hydrofluoric acid (HF) (or lithium fluoride in hydrochloric acid or ammonium difluoride), 3 results in surface functionalized (OH, O or F, noted as T x ) stacks of M n+1 X n T x layers. 10,11 The resulting MX phase multi-layered plates can then undergo exfoliation to produce few or single layered 2D nanosheets of hexagonally arranged metal carbides or nitrides, which are said to resemble graphene sheets, leading to them being named MXenes. 12 MXenes exhibit promising properties for use as Li-ion battery electrodes, 2,8 energy storage supercapacitors, 1,13 and selective heavy-metal adsorption.…”

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Selective Calixarene‐Directed Synthesis of MXene Plates, Crumpled Sheets, Spheres, and Scrolls

Vaughn

Ball

Heil

et al. 2017

Chemistry A European J

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Fully exploiting the electronic and mechanical properties of 2D laminar materials not only requires efficient and effective means of their exfoliation into low dimensional layers, but also necessitates a means of changing their morphology so as to explore any enhancement that this may offer. MXenes are a rapidly emerging new class of such laminar materials with unique properties. However, access to other morphologies of MXenes has not yet been fully realised. To this end we have developed the synthesis of MXenes (Ti2C) as plates, crumpled sheets, spheres and scrolls, which involves selective intercalation of p‐phosphonic calix[n]arenes, with control in morphology arising from the choice of the size of the macrocycle, n=4, 5, 6, or 8. This opens up wider avenues of discovery/design for new morphologies from the wider family of MXenes beyond Ti2C, along with opportunities to exploit any new physico‐chemical properties proffered.

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“…The exfoliation process is carried out by selectively etching away the 'A' layers by hydrofluoric acid (HF) alone or by hydrochloric acid (HCl) combined with pre-dissolved fluoride salts. [13][14][15][16] The resulting material consists of loosely bonded layers of M n+1 X n T x , where T represents surface functionalization by -OH, -F and/or -O groups, [17][18][19] that can subsequently be delaminated via sonication into 3, 5, or 7-atom thick 2D flakes, depending on the value of n. 14,20,21 MXenes -of which more than 20 varying compositions have been synthesized to date, 11,12,[22][23][24][25][26] -possess a unique combination of high electrical conductivities and hydrophilicity. They are thus being explored for a host of applications, such as electrodes for energy storage, 14,[27][28][29] ) unless CC License in place (see abstract).…”

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Electrophoretic Deposition of Two-Dimensional Titanium Carbide (MXene) Thick Films

Collini

Kota

Dillon

et al. 2017

J. Electrochem. Soc.

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Herein, we demonstrate the fabrication of Ti 3 C 2 T x MXene films using electrophoretic deposition (EPD). A systematic study under constant voltage conditions from aqueous and propylene carbonate-based suspensions was performed to investigate the effects of the EPD process parameters on film morphology, flake orientation, and functional properties. From measured suspension properties, the kinetics of deposition from both suspension media were successfully described by the well-established Sarkar model of EPD. Remarkably, EPD-processed films have electrical conductivities of 7400 S/cm, on par with the highest values reported in the literature for Ti 3 C 2 T x MXene. When employed as electrochemical capacitor electrodes in 1 M H 2 SO 4 , the capacitances were comparable to literature values. Given the process scalability and the morphological control that is possible, these results bode well for EPD as a fast, high-throughput method for making MXene films. Electrophoretic deposition (EPD) is a process wherein an electric field is applied to a stable colloidal suspension in between two electrodes.1 As a consequence, two distinct processes occur, as shown in Figure 1a: (1) charged particles in the colloid move toward the electrode of opposite polarity to that of the particles' surface charge (electrophoresis) and, (2) a solid deposit is formed by coagulation at the suspension-electrode interface (deposition). This technique is well-studied and successfully implemented for high-throughput production of dense, void-free ceramic structures ranging from thin coatings to bulk layers several centimeters thick.2 Because of the flexibility and scalability of the deposition apparatus (e.g. power sources and size/shape of deposition electrodes and cell), fast deposition rates, and excellent microstructural control compared to other processing methods, EPD has been used for commercial-scale production of various engineering and traditional ceramics. [2][3][4] In recent years, EPD has also become a versatile technique for making monolithic films and nanocomposites of two-dimensional (2D) materials -such as graphene, transition metal dichalcogenides, and layered transition metal oxides 5-10 -due to advances in colloidal processing. Recently, we discovered a new family of two-dimensional (2D) early transition metal carbides and nitrides, that we labeled MXene, because they are derived from the MAX phases and share properties similar to graphene. 11,12 The MAX phase composition is M n+1 AX n , where M is an early transition metal, A is an A-group element (mostly group 13 and 14 elements), X is carbon and/or nitrogen, and n = 1 to 3. The exfoliation process is carried out by selectively etching away the 'A' layers by hydrofluoric acid (HF) alone or by hydrochloric acid (HCl) combined with pre-dissolved fluoride salts. [13][14][15][16] The resulting material consists of loosely bonded layers of M n+1 X n T x , where T represents surface functionalization by -OH, -F and/or -O groups, [17][18][19] that can subsequently be delaminated...

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NMR reveals the surface functionalisation of Ti₃C₂MXene

Cited by 802 publications

References 19 publications

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

Selective Calixarene‐Directed Synthesis of MXene Plates, Crumpled Sheets, Spheres, and Scrolls

Electrophoretic Deposition of Two-Dimensional Titanium Carbide (MXene) Thick Films

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NMR reveals the surface functionalisation of Ti3C2MXene

Cited by 802 publications

References 19 publications

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

Selective Calixarene‐Directed Synthesis of MXene Plates, Crumpled Sheets, Spheres, and Scrolls

Electrophoretic Deposition of Two-Dimensional Titanium Carbide (MXene) Thick Films

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NMR reveals the surface functionalisation of Ti₃C₂MXene