Raman spectroscopic investigations on transition‐metal dichalcogenides MX<sub>2</sub> (M = Mo, W; X = S, Se) at high pressures and low temperature

Bhatt, S. J.; Deshpande, M. P.; Sathe, Vasant; Rao, Rekha; Chaki, Sunil H.

doi:10.1002/jrs.4580

Cited by 78 publications

(73 citation statements)

References 52 publications

(122 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[34][35][36][37] The existence of the shear mode is due to the vibration of two adjacent rigid layers of MoSe 2 which confirmed the layered structure of as-grown MoSe 2 . [34][35][36][37] The existence of the shear mode is due to the vibration of two adjacent rigid layers of MoSe 2 which confirmed the layered structure of as-grown MoSe 2 .…”

mentioning

confidence: 53%

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

Yousaf

Wang

Chen

et al. 2019

Advanced Energy Materials

233

157

View full text Add to dashboard Cite

attention because of its low cost and abundant supply of sodium. [1][2][3] However, because of its narrow interlayer spacing ≈0.34 nm, the larger size of Na + compared to Li + makes it difficult if not unsuitable for intercalation in graphite, which is commercially employed for LIB. [4][5][6] Further, the large radius of Na + in SIB electrodes produces sluggish electrochemical kinetics, provides higher diffusion barriers, and causes large volume expansion which leads to low rate capability and poor cyclic stability. [7,8] The ionization potential of Na + is also lower than Li + which results in a lower operating voltage and consequently, a lower energy density. [9] A lot of efforts in the development of advanced anode materials for SIBs have been proposed to address these issues.Recently, 2D transition metal dichalcogenides (TMDCs) have received considerable attention in electrochemical energy storage and conversion devices due to their layered structure, and the favorable electronic, chemical, and mechanical properties and stability. [10][11][12] TMDCs such as MoS 2 are often considered a promising anode candidate for LIBs. [13] However, when MoS 2 is employed in SIBs, it displays a lower capacity and a poor cyclic stability as a result of the low intrinsic conductivity and the small interlayer distance (≈0.62 nm). [14] In contrast, MoSe 2 possesses a slightly larger interlayer distance (≈0.64 nm) and better electrical conductivity due to small bandgap (≈1.1 eV). Moreover, it possesses higher theoretical capacity (≈422 mAh g −1 ) [10,15] than graphite (≈35 mAh g −1 ) [6] which makes it one of the most promising TMDC candidates for SIBs. However, the practical applications of MoSe 2 as an anode is limited by capacity fading due to the large volume expansion during long charging/discharging processes and the poor rate capability due to the low intrinsic electrical conductivity. [10] Modifying the nanostructure of the SIB electrodes can often solve some of these problems. For example, expanding the interlayer distance of MoSe 2 can lead to an improvement of the Na + storage and reducing the Na + diffusion barrier energy can enhance the reaction kinetics for the Na + intercalation/deintercalation. [16] Due to the high surface energy and weak van der Waal interactions between layers, Freestanding composite structures with embedded transition metal dichalcogenides (TMDCs) as the active material are highly attractive in the development of advanced electrodes for energy storage devices. Most 3D electrodes consist of a bilayer design involving a core-shell combination. To further enhance the gravimetric and areal capacities, a 3D trilayer design is proposed that has MoSe 2 as the TMDC sandwiched in-between an inner carbon nanotube (CNT) core and an outer carbon layer to form a CNT/ MoSe 2 /C framework. The CNT core creates interconnected pathways for the e − /Na + conduction, while the conductive inert carbon layer not only protects the corrosive environment between the electrolyte and MoSe 2 but also is fully tunable fo...

show abstract

mentioning

confidence: 53%

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

Yousaf

Wang

Chen

et al. 2019

Advanced Energy Materials

233

157

View full text Add to dashboard Cite

show abstract

“…It is this sandwiched structure that endows MoS 2 with the important mechanical properties for solid lubricants 6,7 . The electronic, optical, and lattice dynamical properties have been under intense investigations 2,3,8 . The research on multilayers of MoS 2 , among many other multilayers of TMDs, has been fueled by their novel properties intrinsic to two-dimensional materials.…”

Section: Introductionmentioning

confidence: 99%

Direct calculation of the linear thermal expansion coefficients ofMoS2via symmetry-preserving deformations

Gan

Liu

2016

Phys. Rev. B

View full text Add to dashboard Cite

Using density-functional perturbation theory and the Grüneisen formalism, we directly calculate the linear thermal expansion coefficients (TECs) of a hexagonal bulk system MoS2 in the crystallographic a and c directions. The TEC calculation depends critically on the evaluation of a temperature-dependent quantity Ii(T ), which is the integral of the product of heat capacity and Γi(ν), of frequency ν and strain type i, where Γi(ν) is the phonon density of states weighted by the Grüneisen parameters. We show that to determine the linear TECs we may use minimally two uniaxial strains in the z direction, and either the x or y direction. However, a uniaxial strain in either the x or y direction drastically reduces the symmetry of the crystal from a hexagonal one to a base-centered orthorhombic one. We propose to use an efficient and accurate symmetry-preserving biaxial strain in the xy plane to derive the same result for Γ(ν). We highlight that the Grüneisen parameter associated with a biaxial strain may not be the same as the average of Grüneisen parameters associated with two separate uniaxial strains in the x and y directions due to possible preservation of degeneracies of the phonon modes under a biaxial deformation. Large anisotropy of TECs is observed where the linear TEC in the c direction is about 1.8 times larger than that in the a or b direction at high temperatures. Our theoretical TEC results are compared with experiment. The symmetry-preserving approach adopted here may be applied to a broad class of two lattice-parameter systems such as hexagonal, trigonal, and tetragonal systems, which allows many complicated systems to be treated on a first-principles level.

show abstract

“…An early XRD study showed that the pristine 2 H c structure of WSe 2 was stable up to 35.8 GPa22. Later, a Raman investigation confirmed no structural anomaly up to 20 GPa23. Recently, a first-principles study revealed an anomaly at 40 GPa consistently in the bulk modulus, Young’s modulus and Poisson’s ratio of WSe 2 , which may imply a possible structural transition2124.…”

mentioning

confidence: 99%

Pressure-induced iso-structural phase transition and metallization in WSe2

Wang

Chen

Zhou

et al. 2017

Sci Rep

View full text Add to dashboard Cite

We present in situ high-pressure synchrotron X-ray diffraction (XRD) and Raman spectroscopy study, and electrical transport measurement of single crystal WSe2 in diamond anvil cells with pressures up to 54.0–62.8 GPa. The XRD and Raman results show that the phase undergoes a pressure-induced iso-structural transition via layer sliding, beginning at 28.5 GPa and not being completed up to around 60 GPa. The Raman data also reveals a dominant role of the in-plane strain over the out-of plane compression in helping achieve the transition. Consistently, the electrical transport experiments down to 1.8 K reveals a pressure-induced metallization for WSe2 through a broad pressure range of 28.2–61.7 GPa, where a mixed semiconducting and metallic feature is observed due to the coexisting low- and high-pressure structures.

show abstract

Raman spectroscopic investigations on transition‐metal dichalcogenides MX₂ (M = Mo, W; X = S, Se) at high pressures and low temperature

Cited by 78 publications

References 52 publications

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

Direct calculation of the linear thermal expansion coefficients ofMoS2via symmetry-preserving deformations

Pressure-induced iso-structural phase transition and metallization in WSe2

Contact Info

Product

Resources

About

Raman spectroscopic investigations on transition‐metal dichalcogenides MX2 (M = Mo, W; X = S, Se) at high pressures and low temperature

Cited by 78 publications

References 52 publications

A 3D Trilayered CNT/MoSe2/C Heterostructure with an Expanded MoSe2 Interlayer Spacing for an Efficient Sodium Storage

A 3D Trilayered CNT/MoSe2/C Heterostructure with an Expanded MoSe2 Interlayer Spacing for an Efficient Sodium Storage

Direct calculation of the linear thermal expansion coefficients ofMoS2via symmetry-preserving deformations

Pressure-induced iso-structural phase transition and metallization in WSe2

Contact Info

Product

Resources

About

Raman spectroscopic investigations on transition‐metal dichalcogenides MX₂ (M = Mo, W; X = S, Se) at high pressures and low temperature

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage