Hydrothermal synthesis of stable metallic 1T phase WS<sub>2</sub> nanosheets for thermoelectric application

Piao, Mingxing; Hu, Jin; Wang, Xiao; Yao, Chunde; Zhang, Heng; Li, Chaolong; Shi, Haofei; Joo, Min‐Kyu

doi:10.1088/1361-6528/aa9bfe

Cited by 58 publications

(44 citation statements)

References 40 publications

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“…The sharp peak of Sn 0.35 W 0.65 S 2 at ≈15.6° is diminished for Sn 0.3 W 0.7 S 2 , which may be due to the formation of the T′ phase structure and, consequently, the formation of more defects. The diffraction peak at 31.50° corresponds to the (022) reflection of metallic 1T′‐WS 2 nanosheets . The change of the XRD peak caused by the phase transition is consistent with that reported in the literature .…”

Section: Resultssupporting

confidence: 89%

“…The diffraction peak at 31.50° corresponds to the (022) reflection of metallic 1T′‐WS 2 nanosheets . The change of the XRD peak caused by the phase transition is consistent with that reported in the literature . Synthetic Sn 0.3 W 0.7 S 2 edges appear curled and ultrathin, as shown in Figure c and Figures S6–S8 in the Supporting Information.…”

Section: Resultssupporting

confidence: 88%

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Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction

Shao

Xue

et al. 2019

Adv Funct Materials

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Crystal phase control still remains a challenge for the precise synthesis of 2D layered metal dichalcogenide (LMD) materials. The T′ phase structure has profound influences on enhancing electrical conductivity, increasing active sites, and improving intrinsic catalytic activity, which are urgently needed for enhancing hydrogen evolution reaction (HER) activity. Theoretical calculations suggest that metastable T′ phase 2D Sn 1−x W x S 2 alloys can be formed by combining W with 1T tin disulfide (SnS 2 ) as a template to achieve a semiconductor-to-metallic transition. Herein, 2D Sn 1−x W x S 2 alloys with varying x are prepared by adjusting the molar ratio of reactants via hydrothermal synthesis, among which Sn 0.3 W 0.7 S 2 displays a maximum of concentration of 81% in the metallic phase and features a distorted octahedral-coordinated metastable 1T′ phase structure. The obtained 1T′-Sn 0.3 W 0.7 S 2 has high intrinsic electrical conductivity, lattice distortion, and defects, showing a prominently improved HER catalytic performance. Metallic Sn 0.3 W 0.7 S 2 coupled with carbon black exhibits at least a 215-fold improvement compared to pristine SnS 2 . It has excellent long-term durability and HER activity. This work reveals a general phase transition strategy by using T phase materials as templates and merging heteroatoms to achieve synthetic metastable phase 2D LMDs that have a significantly improved HER catalytic performance.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 88%

Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction

Shao

Xue

et al. 2019

Adv Funct Materials

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“…As one of the most promising 2D materials, transition metal dichalcogenides (TMDs) have attracted significant attention due to their exceptional optical, electronic, chemical properties, and gained wide‐ranging applications such as field–effect transistors, energy storage, electrocatalysis, and so on. Current strategies for the synthesis of 2D TMDs primarily include chemical exfoliation, chemical vapor deposition (CVD), and liquid‐phase syntheses . Chemical exfoliation can obtain monolayer TMDs, but this process usually involves the intercalation‐induced phase transformation and the alteration of the pristine properties.…”

Section: Introductionmentioning

confidence: 99%

Mass Production of High‐Quality Transition Metal Dichalcogenides Nanosheets via a Molten Salt Method

Jin

et al. 2019

Adv Funct Materials

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2D transition metal dichalcogenides (TMDs) are well suited for energy storage and field-effect transistors because of their thickness-dependent chemical and physical properties. However, as current synthetic methods for 2D TMDs cannot integrate both advantages of liquid-phase syntheses (i.e., massive production and homogeneity) and chemical vapor deposition (i.e., high quality and large lateral size), it still remains a great challenge for mass production of high-quality 2D TMDs. Here, a molten salt method to massively synthesize various high-crystalline TMDs nanosheets (MoS 2 , WS 2 , MoSe 2 , and WSe 2 ) with the thicknesses less than 5 nm is reported, with the production yield over 68% with the reaction time of only several minutes. Additionally, the thickness and size of the as-synthesized nanosheets can be readily controlled through adjusting reaction time and temperature. The assynthesized MoSe 2 nanosheets exhibit good electrochemical performance as pseudocapacitive materials. It is further anticipates that this work will provide a promising strategy for rapid mass production of high-quality nonoxides nanosheets for energy-related applications and beyond.

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“…The XRD data for the nanorods (formed using 20 min of laser treatment) and untreated bulk flakes of WS 2 and MoS 2 are presented in Figure c,d, respectively. The untreated WS 2 sample shows characteristic 2H phase peaks corresponding to (002), (004), (100), and (101) planes, and a peak at 16° corresponding to the (004) plane in the 1T phase . However, after the laser treatment, the peaks owing to reflections from the (100) and (101) planes disappear for the WS 2 nanorods, which is indicative of exfoliation of the bulk flakes .…”

Section: Resultsmentioning

confidence: 99%

“…The higher conductivity is also attributed, at least in part, to the significant increase in the amount of 1T (metallic) phase present in the nanorods, as observed by XRD. WS 2 in the 1T phase has a zigzag chain superlattice structure with a negligible energy gap at the fermi level, leading to a large carrier concentration and metallic nature …”

Section: Resultsmentioning

confidence: 99%

Laser‐Directed Assembly of Nanorods of 2D Materials

Ibrahim

Novodchuk

Mistry

et al. 2019

Small

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transparency thus connected networks of 1D nanomaterials [5] have been studied as a viable alternative to thin films of indium tin oxide, which suffer from drawbacks such as brittleness and indium scarcity. [6] Materials such as graphene and transition metal dichalcogenides (TMDs) exhibit excellent electrical properties due to their "flat" 2D chemical structure. Sheets or flakes of these materials can allow for large area coverage with high conductivity but typically at the expense of transparency. [7,8] An approach to improving transparency is utilizing these materials in 1D nanorod-like structures. Carbon nanotubes (CNTs) are the most popular 1D variant of graphene and have been utilized to form large area conducting films, although challenges remain with respect to their purification [9,10] and aggregation. [5] As an alternative to CNTs, the synthesis of carbon-based nanorods has been reported by utilizing arc discharge [11] and microwave plasma chemical vapor deposition (CVD) [12] methods. However, the arc discharge method requires an extensive filtering (Soxhlet extraction) and drying process, while the CVD method requires a high power and temperature (e.g., 850 °C). The growth of graphene nanoribbons has also been reported by ultrahigh vacuum thermal evaporation [13] and hydrothermal techniques, [14] yielding lengths of 20-450 nm and widths of 2-40 nm.In regards to TMDs, molybdenum disulfide (MoS 2 ) nanorods have been synthesized via a redox reaction in an aqueous solution (yielding a nanorod mixture of binary oxides (Mo x O y ) and binary sulfides (Mo x S y )), [15] hydrothermal synthesis, [16] and hydrothermal synthesis of MoO 3 nanorods combined with sulfurization. [17] Similar to MoS 2 , the synthesis of tungsten disulfide (WS 2 ) nanorods has been accomplished by lengthy hydrothermal [18,19] and sulfidation [20] methods. Zhang et al. used high energy ball milling of WS 2 powder for 122 h, after which the powder was used as a precursor in a hydrothermal reaction for nanorod growth. [21] Ball milling methods have also been used to produce boron nitride (BN) nanorods. Boron carbide powders were milled for 100 h and subsequently treated with nitrogen at high temperature to produce BN nanorods. [22][23][24] In another approach, Museur et al. synthesized BN nanorods embedded in amorphous boron suboxides (B x O y ) through UV laser irradiation of a compacted BN powder pellet in a high-pressure nitrogen environment. [25] Table 1 summarizes these previous efforts to fabricate nanorods of 2D materials. Many of these methods require Herein, the previously unrealized ability to grow nanorods and nanotubes of 2D materials using femtosecond laser irradiation is demonstrated. In as short as 20 min, nanorods of tungsten disulfide, molybdenum disulfide, graphene, and boron nitride are grown in solutions. The technique fragments nanoparticles of the 2D materials from bulk flakes and leverages molecular scale alignment by nonresonant intense laser pulses to direct their assembly into nanorods up to several micrometers i...

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Hydrothermal synthesis of stable metallic 1T phase WS₂ nanosheets for thermoelectric application

Cited by 58 publications

References 40 publications

Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction

Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction

Mass Production of High‐Quality Transition Metal Dichalcogenides Nanosheets via a Molten Salt Method

Laser‐Directed Assembly of Nanorods of 2D Materials

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Hydrothermal synthesis of stable metallic 1T phase WS2 nanosheets for thermoelectric application

Cited by 58 publications

References 40 publications

Template‐Assisted Synthesis of Metallic 1T′‐Sn0.3W0.7S2 Nanosheets for Hydrogen Evolution Reaction

Template‐Assisted Synthesis of Metallic 1T′‐Sn0.3W0.7S2 Nanosheets for Hydrogen Evolution Reaction

Mass Production of High‐Quality Transition Metal Dichalcogenides Nanosheets via a Molten Salt Method

Laser‐Directed Assembly of Nanorods of 2D Materials

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Product

Resources

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Hydrothermal synthesis of stable metallic 1T phase WS₂ nanosheets for thermoelectric application

Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction

Template‐Assisted Synthesis of Metallic 1T′‐Sn_0.3W_0.7S₂ Nanosheets for Hydrogen Evolution Reaction