The ultrathin two-dimensional nanosheets of layered transition-metal dichalcogenides (TMDs) have attracted great interest as an important class of materials for fundamental research and technological applications. Solution-phase processes are highly desirable to produce a large amount of TMD nanosheets for applications in energy conversion and energy storage such as catalysis, electronics, rechargeable batteries, and capacitors. Here, we report a rapid exfoliation by supercritical fluid processing for the production of MoS and MoSe nanosheets. Atomic-resolution high-angle annular dark-field imaging reveals high-quality exfoliated MoS and MoSe nanosheets with hexagonal structures, which retain their 2H stacking sequence. The obtained nanosheets were tested for their electrochemical performance in a hybrid Mg-Li-ion battery as a proof of functionality. The MoS and MoSe nanosheets exhibited the specific capacities of 81 and 55 mA h g, respectively, at a current rate of 20 mA g.
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http://dx.doi.org/10.1021/acsomega.7b00379 | DOI Listing |
Adv Mater
December 2024
Institute of Materials Research, Center of Double Helix, Guangdong Provincial Key Laboratory of Thermal Management Engineering and Materials, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China.
Liquid exfoliation is a scalable and effective method for synthesizing 2D nanosheets (NSs) but often induces contamination and defects. Here, liquid metal gallium (Ga) is used to exfoliate bulk layered materials into 2D NSs at near room temperature, utilizing the liquid surface tension and Ga intercalation to disrupt Van der Waals (vdW) forces. In addition, the process can transform the 2H-phase of transition metal dichalcogenides into the 1T'-phase under ambient conditions.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
Department of Physics, Koc University, Rumelifeneri Yolu, Sariyer 34450, Istanbul, Turkey.
Transition metal dichalcogenides (TMDs) exhibit a wide range of electronic properties due to their structural diversity. Understanding their defect-dependent properties might enable the design of efficient, bright, and long-lifetime quantum emitters. Here, we use density functional theory (DFT) calculations to investigate the 2H, 1T, and 1T' phases of MoS, WS, MoSe, WSe and the effect of defect densities on the electronic band structures, focusing on the influence of chalcogen vacancies.
View Article and Find Full Text PDFACS Appl Mater Interfaces
December 2024
Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, United States.
The widespread use of the pesticide glyphosate has raised concerns regarding its potential health and environmental impacts. Consequently, there is an increasing demand for monitoring glyphosate levels in surface waters and food products. Currently, there is no commercially available rapid, field-deployable sensor capable of quantifying glyphosate concentrations in environmental samples.
View Article and Find Full Text PDFNanoscale
December 2024
Department of Physics, BITS-Pilani K. K. Birla Goa Campus, Zuarinagar, Goa-403726, India.
Monolayer 2D transition metal dichalcogenides (TMDs) are known for their direct bandgaps and pronounced excitonic effects, which facilitate efficient light absorption and high photoluminescence (PL). In this study, we report a significant enhancement in PL emission from monolayers of p-type molybdenum disulfide (p-MoS), fabricated on conductive substrates-such as indium tin oxide (ITO) and gold (Au). We attribute this behaviour to the reverse injection of charge carriers from substrates to p-MoS and the subsequent localization of electrons and holes in the substrate and p-MoS, respectively.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
Condensed Matter Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Athens, Greece.
We theoretically investigated the electron-surface optical phonon interaction across the long-range Fröhlich coupling in monolayer transition metal dichalcogenides, such as WS, WSe, MoS, and MoSe monolayers, on SiC and hexagonal BN dielectric substrates. We employed the effective Hamiltonian in the K+(K-) valley of the hexagonal Brillouin zone to assess the electronic energy shifts induced by the interaction between electronic states and surface polar optical phonons. Our results indicate that the interaction between electrons and surface optical phonons depends upon the polar nature of the substrate.
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