Stabilization and strengthening effects of functional groups in two-dimensional titanium carbide

Fu, Zhongheng; Zhang, Q. F.; Legut, Dominik; Chen, Si; Germann, Timothy C.; Lookman, Turab; Du, Shuo; Francisco, Joseph S.; Zhang, R. F.

doi:10.1103/physrevb.94.104103

Cited by 166 publications

(135 citation statements)

References 75 publications

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“…Moreover, we find that all of the elastic constants of the pristine iMXenes increase with F, O, or OH functionalization, suggesting that the functionalized iMXenes have better mechanical properties than the pristine ones. This is in good accordance with previous studies of other pristine and functionalized MXenes [87,88].…”

Section: Mechanical Propertiessupporting

confidence: 93%

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Khazaei

Wang

Sevik

et al. 2018

Phys. Rev. Materials

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Recently, a group of MAX phases, (Mo 2/3 Y 1/3 )2AlC, (Mo 2/3 Sc 1/3 )2AlC, (W 2/3 Sc 1/3 )2AlC, (W 2/3 Y 1/3 )2AlC, and (V 2/3 Zr 1/3 )2AlC, with in-plane ordered double transition metals, named iMAX phases, have been synthesized. Experimentally, some of these MAX phases can be chemically exfoliated into two-dimensional (2D) single-or multilayered transition metal carbides, so-called MXenes. Accordingly, the 2D nanostructures derived from iMAX phases are named iMXenes. Here, we investigate the structural stabilities and electronic structures of the experimentally discovered iMAX phases and their possible iMXene derivatives. We show that the iMAX phases and their pristine, F, or OH-terminated iMXenes are metallic. However, upon O termination, (Mo 2/3 Y 1/3 )2C, (Mo 2/3 Sc 1/3 )2C, (W 2/3 Y 1/3 )2C, and (W 2/3 Sc 1/3 )2C iMXenes turn into semiconductors. The semiconducting iMXenes may find applications in piezoelectricity owing to the absence of centrosymmetry. Our calculations reveal that the semiconducting iMXenes possess giant piezoelectric coefficients as large as 45×10 −10 C/m.

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Section: Mechanical Propertiessupporting

confidence: 93%

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Khazaei

Wang

Sevik

et al. 2018

Phys. Rev. Materials

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“…The structure of OH‐terminated Ti 3 C 2 layers was for the first time proposed on the basis of a density functional theory (DFT) simulation, and the results revealed that the electronic structure of Ti 3 C 2 (OH) 2 layers possesses metallic‐like character, which closely matched the experimental findings . Bare Ti 3 C 2 layers and terminated Ti 3 C 2 T x with specific surface terminations (for example, pure OH, O, F, or combinations thereof) were investigated in computational studies to predict several of their properties including physical and chemical characteristics and applications . To date, the synthesized Ti 3 C 2 T x products using acidic‐fluoride‐containing solutions reveal a mixture of O, OH, and F terminations, which may be optimized by postprocessing to specific terminations, to obtain specific properties and applications.…”

Section: Propertiesmentioning

confidence: 66%

Recent Advances in Layered Ti₃C₂T_x MXene for Electrochemical Energy Storage

Xiong

Bai

et al. 2018

Small

817

434

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Ti C T , a typical representative among the emerging family of 2D layered transition metal carbides and/or nitrides referred to as MXenes, has exhibited multiple advantages including metallic conductivity, a plastic layer structure, small band gaps, and the hydrophilic nature of its functionalized surface. As a result, this 2D material is intensively investigated for application in the energy storage field. The composition, morphology and texture, surface chemistry, and structural configuration of Ti C T directly influence its electrochemical performance, e.g., the use of a well-designed 2D Ti C T as a rechargeable battery anode has significantly enhanced battery performance by providing more chemically active interfaces, shortened ion-diffusion lengths, and improved in-plane carrier/charge-transport kinetics. Some recent progresses of Ti C T MXene are achieved in energy storage. This Review summarizes recent advances in the synthesis and electrochemical energy storage applications of Ti C T MXene including supercapacitors, lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries. The current opportunities and future challenges of Ti C T MXene are addressed for energy-storage devices. This Review seeks to provide a rational and in-depth understanding of the relation between the electrochemical performance and the nanostructural/chemical composition of Ti C T , which will promote the further development of 2D MXenes in energy-storage applications.

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“…To validate our computational approach, we have calculated the elastic properties of graphene by our AELAS code for automatic derivations of elastic property and presented in Table S1 (Supporting Information), which are in good agreement with the previous studies. [30,31] By means of the same procedure, the Young's moduli, Poisson ratio, and shear moduli of Ti 2 CT 2 are calculated and summarized in Table 1 . It is seen that all Ti 2 CT 2 meet the mechanical stability criterion, while Ti 2 CO 1.33 F 0.67 exhibits the highest Young's modulus (222 N m −1 ) among Ti 2 CT 2 with various mixtures of O and F groups, which is comparable to that of Ti 2 CO 2 (241 N m −1 ).…”

Section: Resultsmentioning

confidence: 99%

“…Since a vacuum thickness remained along the z ‐direction, the in‐plane stress imposed on the cell was rescaled by Z to obtain an in‐plane stress without influence on layer thickness, where Z is the dimensional length of the cell along the z ‐direction. For the details of the scheme for stress–strain calculations, the recent publications might be referred …”

Section: Methodsmentioning

confidence: 99%

Surface Electrochemical Stability and Strain‐Tunable Lithium Storage of Highly Flexible 2D Transition Metal Carbides

Chen

Zhang

et al. 2018

Adv Funct Materials

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2D transition metal carbides and/or nitrides (MXenes) have attracted enormous attention because of their potential applications in energy storage, catalysis, and others. The control of surface terminations is generally believed to offer the potential preparation approaches to novel MXenes, while an external strain may provide solution to property modification. However, an atomistic understanding on the stabilization of surface complexity and the influence of strain on electrochemical properties of MXenes are scarce yet much demanded. Herein, taking Ti 2 CT n as a representative MXene, the thermodynamically favorable configurations are explored with a mixture of functional groups under various electrochemical environments. It predicts that five thermodynamically preferable Ti 2 CT n terminated by O and F cofunctionalized groups are discovered, all of which show excellent mechanical flexibility and strength that appear a decreasing trend as increasing F/O ratio. Further investigations on strain-controllable Li-transport of these cofunctionalized Ti 2 CT 2 indicate that a mixture of surface terminations decreases the diffusion barriers, while the uniaxial strain modifies the diffusion pathways of Li atom owing to asymmetrical surface geometry and electronic polarization. These findings provide a view on the modification of properties by controlling surface complexity, demonstrating effective pathways in designing MXenes by electrochemical approach and tuning electrochemical property by strains.

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Stabilization and strengthening effects of functional groups in two-dimensional titanium carbide

Cited by 166 publications

References 75 publications

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Recent Advances in Layered Ti₃C₂T_x MXene for Electrochemical Energy Storage

Surface Electrochemical Stability and Strain‐Tunable Lithium Storage of Highly Flexible 2D Transition Metal Carbides

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Stabilization and strengthening effects of functional groups in two-dimensional titanium carbide

Cited by 166 publications

References 75 publications

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Electronic structures of iMAX phases and their two-dimensional derivatives: A family of piezoelectric materials

Recent Advances in Layered Ti3C2Tx MXene for Electrochemical Energy Storage

Surface Electrochemical Stability and Strain‐Tunable Lithium Storage of Highly Flexible 2D Transition Metal Carbides

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Product

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Recent Advances in Layered Ti₃C₂T_x MXene for Electrochemical Energy Storage