Long-Range Lattice Engineering of MoTe<sub>2</sub> by a 2D Electride

Kim, Sera; Song, Seunghyun; Park, Jong-Ho; Yu, Ho Sung; Cho, Suyeon; Kim, Dohyun; Baik, Jaeyoon; Choe, Duk‐Hyun; Chang, K. J.; Lee, Young Hee; Kim, Sung Wng; Yang, Heejun

doi:10.1021/acs.nanolett.6b05199

Cited by 77 publications

(105 citation statements)

References 32 publications

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“…The seminal example is the layered dicalcium nitride (Ca 2 N) with an Anti-CdCl 2 structure (R-3m), which can be taken as [Ca 2 N] + (e -). Remarkably, the excess electrons from counting oxidation numbers were confined in the space between the [Ca 2 N] + layers, forming dense twodimensional (2D) electron layer, 6,21 promising for electron dopant, [22][23][24][25][26] batteries, 27,28 and plasmonic device applications. [29][30][31] Meanwhile, monolayer Ca 2 N preserving its unique two-dimensional electron layers in interstitial space was predicted to be stable theoretically and subsequently was grown experimentally.…”

Section: Introductionmentioning

confidence: 99%

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

et al. 2019

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Despite their extraordinary properties, electrides are still a relatively unexplored class of materials with only a few compounds grown experimentally. Especially for layered electrides, the current researches mainly focus on several isostructures of Ca 2 N with similar interlayer two-dimensional (2D) anionic electrons. An extensive screening for different layered electrides is still missing. Here, by screening materials with anionic electrons for the structures in Materials Project, we uncover 12 existing materials as new layered electrides. Remarkably, these layered electrides demonstrate completely different properties from Ca 2 N. For example, unusual fully spin-polarized zero-dimensional (0D) anionic electrons are shown in metal halides with MoS 2 -like structures; unique one-dimensional (1D) anionic electrons are confined within the tubes of the quasi-1D structures; a coexistence of magnetic and non-magnetic anionic electrons is found in ZrCl-like structures and a new ternary Ba 2 LiN with both 0D and 1D anionic electrons. These materials not only significantly increase the pool of experimentally synthesizable layered electrides but also are promising to be exfoliated into advanced 2D materials. ASSOCIATED CONTENT Supporting Information.This material is available free of charge via the Internet at http://pubs.acs.org." Basic structural, electronic and magnetic properties, as well as the distribution of anionic electrons of the 12 layered electrides

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Section: Introductionmentioning

confidence: 99%

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

et al. 2019

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“…Transition metal dichalcogenides (TMDs) have attracted a wide range of interests by their polymorphic structures (multiple lattice and electronic structures) and versatile phase transition as a novel way of engineering materials for next generation electronic and catalytic devices . A representative way of manipulating the polymorphs, particularly for group 6 TMDs (e.g., MoS 2 ), is chemical intercalation of electron‐donating alkali metals, such as Li, Na, and K, into the TMDs .…”

Section: Introductionmentioning

confidence: 99%

Vertical Heterophase for Electrical, Electrochemical, and Mechanical Manipulations of Layered MoTe₂

Eshete

Ling

Kim

et al. 2019

Adv Funct Materials

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Phase engineering is a breakthrough for various electronic and energy device applications with transition metal dichalcogenides (TMDs). Chemical methods, such as lithium intercalation, are mostly used for phase engineering, which achieves atomically thin flakes and high catalytic performances in several group 6 TMDs including MoS 2 . However, chemical methods cannot be applied to MoTe 2 , a widely investigated group 6 TMD with intriguing semiconducting, topological, and catalytic properties. The lack of modifying MoTe 2 by chemical methods remains a puzzling issue considering the small energy difference between the polymorphs of MoTe 2 . Here, a convectionassisted lithium ion intercalation and phase transition is reported to achieve a vertical heterophase in a MoTe 2 crystal. The vertical heterophase in MoTe 2 reduces the Schottky barrier with metal electrodes down to 66 meV, enhancing the overall ion conductance for electrochemical hydrogen production. Moreover, the weakened adhesion of the 1T' phase layers on the top and bottom surfaces in the vertical heterophase, formed by the intercalation, enables a unique surface tension-driven exfoliation of MoTe 2 flakes. The heterophase chemical engineering suggests a new platform for hybrid catalysts and next-generation electronic devices based on 2D materials.

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“…Li or K functionalization reduces the TMDs and the gliding of the S planes results in the transformation from 2H to 1T. Functionalization by other electron donating species such as Re, Tc, and Mn can also induce the transformation . The electron donated by the alkali metals alters the d electron count of the metal (Mo or W), and it splits in the octahedral coordination to have three unpaired electrons in the valence band d orbitals.…”

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confidence: 99%

An Insight into the Phase Transformation of WS₂ upon Fluorination

et al. 2018

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reduces the TMDs and the gliding of the S planes results in the transformation from 2H to 1T. Functionalization by other electron donating species such as Re, Tc, and Mn can also induce the transformation. [7][8][9][10][11] The electron donated by the alkali metals alters the d electron count of the metal (Mo or W), and it splits in the octahedral coordination to have three unpaired electrons in the valence band d orbitals. However, the 1T phase is highly unstable and converts back into 2H phase with time and temperature. [12] Apart from alkali metals, several attempts have been made on the covalent functionalization of 2H and 1T phases by organic functional groups. [13][14][15][16] Sarkar et al. decorated the 2D layers with metal nanoparticles which changed the transfer characteristics of the 2D devices and demonstrated its capability as a gas sensor. [17] Theoretically, hydrogenation also converts the 2H semiconducting phase into the metallic phase. [18] A transformation from an n-type to a p-type semiconductor, a nonmagnetic to a magnetic material and a boost in the catalytic activity was achieved through controlled and selective doping of TMDs by transition metals. [19] An interesting deviation from extrinsic doping was intrinsic doping by the incorporation of islands of 1T in a lattice of 2H semiconducting nanosheets, where the The transformation from semiconducting to metallic phase, accompanied by a structural transition in 2D transition metal dichalcogenides has attracted the attention of the researchers worldwide. The unconventional structural transformation of fluorinated WS 2 (FWS 2 ) into the 1T phase is described. The energy difference between the two phases debugs this transition, as fluorination enhances the stability of 1T FWS 2 and makes it energetically favorable at higher F concentration. Investigation of the electronic and optical nature of FWS 2 is supplemented by possible band structures and bandgap calculations. Magnetic centers in the 1T phase appear in FWS 2 possibly due to the introduction of defect sites. A direct consequence of the phase transition and associated increase in interlayer spacing is a change in friction behavior. Friction force microscopy is used to determine this effect of functionalization accompanied phase transformation. FluorinationThe unique properties found in graphene and later in monolayers of other materials thrust the research on transition metal dichalcogenides (TMDs) as evidenced from the publications on TMDs in the past decade. [1][2][3][4][5] A distinctive property of TMDs is their polymorphic structural and electronic characteristics. For instance, in group 6 chalcogenides such as MoS 2 and WS 2 , when the sulfur (S) atoms occur on top of each other, it results in trigonal prismatic symmetry in the commonly called 2H semiconducting phase and the displaced S atoms results in octahedral symmetry in the 1T metallic phase. [6] Li or K functionalization

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Long-Range Lattice Engineering of MoTe₂ by a 2D Electride

Cited by 77 publications

References 32 publications

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

Vertical Heterophase for Electrical, Electrochemical, and Mechanical Manipulations of Layered MoTe₂

An Insight into the Phase Transformation of WS₂ upon Fluorination

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Long-Range Lattice Engineering of MoTe2 by a 2D Electride

Cited by 77 publications

References 32 publications

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

Discovery of Hidden Classes of Layered Electrides by Extensive High-Throughput Material Screening

Vertical Heterophase for Electrical, Electrochemical, and Mechanical Manipulations of Layered MoTe2

An Insight into the Phase Transformation of WS2 upon Fluorination

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Long-Range Lattice Engineering of MoTe₂ by a 2D Electride

Vertical Heterophase for Electrical, Electrochemical, and Mechanical Manipulations of Layered MoTe₂

An Insight into the Phase Transformation of WS₂ upon Fluorination