Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes)

Anasori, Babak; Xie, Yu; Beidaghi, Majid; Lu, Jun; Hosler, Brian; Hultman, Lars; Kent, Paul; Gogotsi, Yury; Barsoum, Michel W.

doi:10.1021/acsnano.5b03591

Cited by 1,490 publications

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“…13 This in turn implies that Mo-based MXenes can now be fabricated and tested. This was accomplished 28 and the results are encouraging.…”

Section: Discussionmentioning

confidence: 88%

“…28 The major goal of this study is to better understand the crystal structures and phase stabilities of Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 . The latter is a 413 phase that has just been discovered.…”

Section: Introductionmentioning

confidence: 99%

“…The latter is a 413 phase that has just been discovered. 28 For brevity's sake, the notations Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 will be used. However, as shown below, the Mo:Ti ratio can deviate substantially from the nominal 2:1 or 2:2.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

Anasori

Dahlqvist

Halim

et al. 2015

Journal of Applied Physics

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Herein, we report on the phase stabilities and crystal structures of two newly discovered ordered, quaternary MAX phases-Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 -synthesized by mixing and heating different elemental powder mixtures of mMo:(3-m)Ti:1.1Al:2C with 1.5 m 2.2 and 2Mo: 2Ti:1.1Al:2.7C to 1600 C for 4 h under Ar flow. In general, for m ! 2 an ordered 312 phase, (Mo 2 Ti)AlC 2 , was the majority phase; for m < 2, an ordered 413 phase (Mo 2 Ti 2 )AlC 3 , was the major product. The actual chemistries determined from X-ray photoelectron spectroscopy (XPS) are Mo 2 TiAlC 1.7 and Mo 2 Ti 1.9 Al 0.9 C 2.5 , respectively. High resolution scanning transmission microscopy, XPS and Rietveld analysis of powder X-ray diffraction confirmed the general ordered stacking sequence to be Mo-Ti-Mo-Al-Mo-Ti-Mo for Mo 2 TiAlC 2 and Mo-Ti-Ti-Mo-Al-Mo-Ti-TiMo for Mo 2 Ti 2 AlC 3 , with the carbon atoms occupying the octahedral sites between the transition metal layers. Consistent with the experimental results, the theoretical calculations clearly show that M layer ordering is mostly driven by the high penalty paid in energy by having the Mo atoms surrounded by C in a face-centered configuration, i.e., in the center of the M nþ1 X n blocks. At 331 GPa and 367 GPa, respectively, the Young's moduli of the ordered Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 are predicted to be higher than those calculated for their ternary end members. Like most other MAX phases, because of the high density of states at the Fermi level, the resistivity measurement over 300 to 10 K for both phases showed metallic behavior. V C 2015 AIP Publishing LLC.

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“…13 This in turn implies that Mo-based MXenes can now be fabricated and tested. This was accomplished 28 and the results are encouraging.…”

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

Anasori

Dahlqvist

Halim

et al. 2015

Journal of Applied Physics

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232

180

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“…[22][23][24][25][26][27] Recently, considerable efforts have been made to further expand the family of 2D carbides. On the basis of a substitutional solid solution method, Gogotsi and Barsoum et al [28] successfully synthesized Mo2TiC2Tz, Mo2Ti2C3Tz, and Cr2TiC2TzMXenes, and surface dependent electrochemical behaviors in the case of Mo2TiC2Tz have been revealed. Moreover, Mo2CTz MXene [29] has been synthesized through selective etching of gallium (Ga) from a thin film of the new ternary nanolaminated Mo2Ga2C.…”

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confidence: 99%

A Two‐Dimensional Zirconium Carbide by Selective Etching of Al₃C₃ from Nanolaminated Zr₃Al₃C₅

et al. 2016

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During the past decade, two-dimensional (2D) materials have attracted extensive attention due to their high surface area to volume ratio, unique electronic structures and physiochemical properties derived from their low dimensionality. [1][2][3][4][5][6][7] Graphene, the most studied 2D material with ultrahigh mechanical strength, [8][9] excellent electronic and thermal conductivities, [1,[10][11] exhibits potential applications in electrochemical energy storage, transparent electrodes, and nano-composites. [12] However, due to its intrinsic zero bandgap and simple chemistry, applications of graphene are restricted in some aspects, such as field effect transistors.[10] Thus, investigations on other 2D materials are performed, especially for those 2D materials with two or more composition elements, such as metal oxide, layered metal chalcogenides (LMDCs), hexagonal boron nitride(BN), hydroxides, etc. [6,13] In recent years, a new class of 2D materials called MXenes, have emerged [14] Members in this family are described by the general formula of Mn+1XnTz (wherein M is an early transition metal, X is C and/or N, n is 1, 2, 3, and Tz denotes surface terminated functional groups). [14] Generally, MXenes are produced by the selective etching of Al layers from their parental layered ternary MAX phases, a large group which comprises more than 70 members. [15][16] Through selective etching of aluminium layers, experimental investigations have successfully identified about 10 different MXenes, Ti3C2Tz, Ti2CTz, Ta4C3Tz, TiNbCTz, (V0.5,Cr0.5)3C2Tz, Ti3CNTz, Nb2CTz, V2CTz, and Nb4C3Tz. [14,17] Most of the synthesized MXenes are metallic, [18] hydrophilic, and predicted to have high elastic moduli, implying potential application as reinforcement of polymer. [19][20] The existance of Dirac electrons in some MXenes has also been theoretically predicted .[21] Moreover, similar to graphene, MXenes are promising candidate electrode materials for lithium-ion batteries and supercapacitors by facile intercalation of Li ions into the MXene layers. [22][23][24][25][26][27] Recently, considerable efforts have been made to further expand the family of 2D carbides. On the basis of a substitutional solid solution method, Gogotsi and Barsoum et al. [28] successfully synthesized Mo2TiC2Tz, Mo2Ti2C3Tz, and Cr2TiC2TzMXenes, and surface dependent electrochemical behaviors in the case of Mo2TiC2Tz have been revealed. Moreover, Mo2CTz MXene [29] has been synthesized through selective etching of gallium (Ga) from a thin film of the new ternary nanolaminated Mo2Ga2C. [30][31] Besides, large-area high-quality 2D α-Mo2C, WC, and TaC crystals have been fabricated by a chemical vapour deposition (CVD) process.[32] However, potential MXene compounds in materials systems where Al-containing MAX phases are not established, such as Hf2C and Zr2C, are yet to be produced.Herein, for the first time, we report the preparation of Zr-containing 2D carbide based on selective extraction of Al-C units from an alternative layered ternary Zr3Al3C5, benefiting from ...

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“…and prepared in experiment, such as the transition metal dichalchogenides, 4-7 transitionmetal carbides (MXenes), 8,9 monolayer black phosphorus (BP) (termed phosphorene), 10 etc.…”

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confidence: 99%

Novel Excitonic Solar Cells in Phosphorene–TiO₂ Heterostructures with Extraordinary Charge Separation Efficiency

Zhou

Zhang

Zhuo

et al. 2016

J. Phys. Chem. Lett.

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Constructing van der Waals heterostructures is an efficient approach to modulate the electronic structure, to advance the charge separation efficiency, and thus to optimize the optoelectronic property. Here, we theoretically investigated the phosphorene interfaced with TiO2(110) surface (1L-BP/TiO2) with a type-II band alignment, showing enhanced photoactivity. The 1L-BP/TiO2 excitonic solar cell (XSC) based on the 1L-BP/TiO2 exhibits large built-in potential and high power conversion efficiency (PCE), dozens of times higher than conventional solar cells, comparable to MoS2/WS2 XSC. The nonadiabatic molecular dynamics simulation shows the ultrafast electron transfer time of 6.1 fs, and slow electron–hole recombination of 0.58 ps, yielding >98% internal quantum efficiency for charge separation, further guaranteeing the practical PCE. Moreover, doping in phosphorene has a tunability on built-in potential, charge transfer, light absorbance, as well as electron dynamics, which greatly helps to optimize the optoelectronic efficiency of a XSC.

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Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes)

Cited by 1,490 publications

References 50 publications

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

A Two‐Dimensional Zirconium Carbide by Selective Etching of Al₃C₃ from Nanolaminated Zr₃Al₃C₅

Novel Excitonic Solar Cells in Phosphorene–TiO₂ Heterostructures with Extraordinary Charge Separation Efficiency

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Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes)

Cited by 1,490 publications

References 50 publications

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

Experimental and theoretical characterization of ordered MAX phases Mo2TiAlC2 and Mo2Ti2AlC3

A Two‐Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C5

Novel Excitonic Solar Cells in Phosphorene–TiO2 Heterostructures with Extraordinary Charge Separation Efficiency

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A Two‐Dimensional Zirconium Carbide by Selective Etching of Al₃C₃ from Nanolaminated Zr₃Al₃C₅

Novel Excitonic Solar Cells in Phosphorene–TiO₂ Heterostructures with Extraordinary Charge Separation Efficiency