The combination of high-quality Al2 O3 dielectric and thiol chemistry passivation can effectively reduce the density of interface traps and Coulomb impurities, leading to a significant improvement of the mobility and a transition of the charge transport from the insulating to the metallic regime. A record high mobility of 83 cm(2) V(-1) s(-1) (337 cm(2) V(-1) s(-1) ) is reached at room temperature (low temperature) for monolayer WS2 . A theoretical model for electron transport is also developed.

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Lots of research studies reveal that the surface atoms on the top/bottom facets of the nanosheets are the key features in enhancing electrocatalytic activity while the edge and corner sites of electrocatalysts often possess superior activity. Herein, we report 2D dendritic PdAgPt ternary nanoalloys with abundant crystal defects such as steps, twin boundary, and atomic holes, which can effectively work as catalytic active-sites. The morphology of PdAgPt nanoalloys can be regulated readily from dendritic nanosheets to nanowheels. Compared with binary Pd68Ag32 nanodendrites, Pd62Pt38 nanospheres, and Pt/C catalyst, the composition- and morphology-optimized Pd43Ag21Pt36 nanowheels exhibit the best mass/specific activity and stability for methanol/ethanol oxidation reaction (MOR/EOR). The mass peak current density for EOR/MOR of Pd43Ag21Pt36 is 7.08/3.50 times of the Pt/C catalyst. Simultaneously, the hydrogen evolution reaction performance of the Pd43Ag21Pt36 nanowheels in terms of the lowest overpotential of 9 mv at a current density of 10 mA/cm2 and high electrochemical stability is much better than that of binary Pd68Ag32 nanodendrites, Pd62Pt38 nanospheres, and Pt/C.

Nanocomposite Si 1−x Ge x films are deposited by dual-source jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD). The segregations and desorptions of Ge atoms, which dominate the structural evolutions of the films during high-temperature annealing, are investigated. When the annealing temperature (T a ) is 900 • C, the nanocomposite Si 1−x Ge x films are well crystallized, and nanocrystals (NCs) with the core-shell structure form in the films. After being annealed at 1000 • C (above the melting point of bulk Ge), Ge atoms accumulate on the surfaces of Ge-rich films, whereas pits appear on films with lower Ge content, resulting from desorption. Meanwhile, voids are observed in the films. A cone-like structure involving the percolation of the homogeneous clusters and the crystallization of NCs enhances Ge segregation.