Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) have emerged as attractive platforms in next-generation nanoelectronics and optoelectronics for reducing device sizes down to a 10 nm scale. To achieve this, the controlled synthesis of wafer-scale single-crystal TMDs with high crystallinity has been a continuous pursuit. However, previous efforts to epitaxially grow TMD films on insulating substrates (e.g., mica and sapphire) failed to eliminate the evolution of antiparallel domains and twin boundaries, leading to the formation of polycrystalline films. Herein, we report the epitaxial growth of wafer-scale single-crystal MoS2 monolayers on vicinal Au(111) thin films, as obtained by melting and resolidifying commercial Au foils. The unidirectional alignment and seamless stitching of the MoS2 domains were comprehensively demonstrated using atomic- to centimeter-scale characterization techniques. By utilizing onsite scanning tunneling microscope characterizations combined with first-principles calculations, it was revealed that the nucleation of MoS2 monolayer is dominantly guided by the steps on Au(111), which leads to highly oriented growth of MoS2 along the ⟨110⟩ step edges. This work, thereby, makes a significant step toward the practical applications of MoS2 monolayers and the large-scale integration of 2D electronics.

Abstract2D magnetic materials have attracted intense attention as ideal platforms for constructing multifunctional electronic and spintronic devices. However, most of the reported 2D magnetic materials are mainly achieved by the mechanical exfoliation route. The direct synthesis of such materials is still rarely reported, especially toward thickness‐controlled synthesis down to the 2D limit. Herein, the thickness‐tunable synthesis of nanothick rhombohedral Cr2S3 flakes (from ≈1.9 nm to tens of nanometers) on a chemically inert mica substrate via a facile chemical vapor deposition route is demonstrated. This is accomplished by an accurate control of the feeding rate of the Cr precursor and the growth temperature. Furthermore, it is revealed that the conduction behavior of the nanothick Cr2S3 is variable with increasing thickness (from 2.6 to 4.8 nm and >7 nm) from p‐type to ambipolar and then to n‐type. Hereby, this work can shed light on the scalable synthesis, transport, and magnetic properties explorations of 2D magnetic materials.

To gain an atomistic-level understanding of the experimental observation that the cocrystal TNT/CL-20 leads to decreased sensitivity, we carried out reactive molecular dynamics (RMD) simulations using the ReaxFF reactive force field. We compared the thermal decomposition of the TNT/CL-20 cocrystal with that of pure crystals of TNT and CL-20 and with a simple physical mixture of TNT and CL-20. We find that cocrystal has a lower decomposition rate than CL-20 but higher than TNT, which is consistent with experimental observation. We find that the formation of carbon clusters arising from TNT, a carbon-rich molecule, plays an important role in the thermal decomposition process, explaining the decrease in sensitivity for the cocrystal. At low temperature and in the early stage of chemical reactions under high temperature, the cocrystal releases energy more slowly than the simple mixture of CL-20-TNT. These results confirm the expectation that co-crystallization is an effective way to decrease the sensitivity for energetic materials while retaining high performance.

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We report room temperature broad range (ultraviolet to short-wavelength infrared) photodetectors made from few-layer α-In2Se3 nanosheets.

Homogeneous ultrasmall T-Nb O nanocrystallites encapsulated in 1D carbon nanofibers (T-Nb O /CNFs) are prepared through electrospinning followed by subsequent pyrolysis treatment. In a Na half-cell configuration, the obtained T-Nb O /CNFs with the merits of unique microstructures and inherent pseudocapacitance, deliver a stable capacity of 150 mAh g at 1 A g over 5000 cycles. Even at an ultrahigh charge-discharge rate of 8 A g , a high reversible capacity of 97 mAh g is still achieved. By means of kinetic analysis, it is demonstrated that the larger ratio of surface Faradaic reactions of Nb O at high rates is the major factor to achieve excellent rate performance. The prolonged cycle durability and excellent rate performance endows T-Nb O /CNFs with potentials as anode materials for sodium-ion batteries.

We combine spectroscopic ellipsometry (SE), Fourier transform infrared spectroscopy (FT-IR), kinetic Monte Carlo simulations (KMC) and convex corner undercutting analysis in order to characterize and explain the effect of the addition of small amounts of surfactant in alkaline aqueous solutions, such as Triton X-100 in tetra methyl ammonium hydroxide (TMAH). We propose that the surfactant is adsorbed at the silicon-etchant interface as a thin layer, acting as a filter that moderates the surface reactivity by reducing the amount of reactant molecules that reach the surface. According to the SE and FT-IR measurements, the thickness of the adsorbed layer is an orientation-and concentration-dependent quantity, mostly due to the orientation dependence of the surface density of H-terminations and the concentration dependence of the relative rates of the underlying oxidation and etching reactions, which have a direct impact on the number of OH terminations. For partial OH coverage of the surface, the hydration of the OH group effectively acts as an anchoring location for the hydration shell of a surfactant molecule, thus enabling the formation of hydration bridges that amplify the adsorption density of the surfactant. At high concentration, the model explains the large reduction in the etch rate of the exact and vicinal Si{1 1 0} surfaces, and the small changes in the etch rates for the exact and vicinal Si{1 0 0} surfaces. At low concentration, it explains how the etch rate for both families is significantly reduced. The orientation and concentration dependence of the surfactant adsorption explains the dramatic differences in the micron-scale wet-etched patterns obtained using TMAH and TMAH+Triton for microelectromechanical systems applications.

Li ion batteries are basically capable of meeting the growing demands for portable devices and electric vehicles; however, the fast developing society puts forward higher requirements for large-scale electrical energy storage systems. [1,2] In recent years, sodium ion batteries (SIBs) have attracted great attention for their similar physiochemical properties to Li and far more resources. [3-6] However, sluggish Na +-intercalation kinetics hinder the direct utilization of graphite as an anode, though many cathode materials have been developed for SIBs; [7] traditional insertion-type anodes, such as hard carbon, are unable to match them to achieve the best performance. New anode materials with high performances are urgently needed for SIBs. Some anode materials such as P [8-13] and Se [14-20] can deliver large capacities via conversion reactions during sodiation/desodiation. Metals exemplified by Sn [21-30] and Sb [31] undergo alloying reactions also to provide huge capacities. [32] It is obvious that when these two reactions are combined, a better anode could be obtained with desirable performances. Li et al. [33] prepared Sn 4 P 3 /reduced graphene oxide (rGO) hybrids as anodes for SIBs with a capacity of 391 mA h g −1 at 2.0 A g −1. Xiong et al. [34] reported that Sb 2 S 3 on sulfur-doped graphene sheets enables a stable capacity retention of 83% for 900 cycles. However, those materials inevitably suffer from large volume As a promising candidate for large-scale energy storage, sodium-ion batteries (SIBs) have superiority due to their low cost and abundance as a resource. Herein, homogeneous Sb 2 Se 3 nanocrystallites embedded in carbon nanofibers (Sb 2 Se 3 /CNFs) by electrospinning and selenization treatment are prepared. The obtained Sb 2 Se 3 /CNFs exhibit good cycling performance, high reversible capacity, and excellent rate capability as anodes for SIBs. The outstanding performances are attributed to a combination of Na + intercalation, conversion reaction, and alloying with Sb 2 Se 3 , disclosed through in-situ X-ray diffraction. Meanwhile, unique nanostructures provide large contact surface and tolerant accommodation to volume expansion which bring high reversibility and long cycle durability. This distinctive material shows prospective applications of SIBs especially under high current density. expansion with severe capacity decay. [35] It is needed to apply some special strategies like carbon coating for better electrochemical performances. [36] Antimony selenide (Sb 2 Se 3) demonstrates excellent photoelectronic properties and has been widely applied in fieldemission devices and photodetectors. [37] Although not many studies have involved its application as anodes for SIBs, its properties show a very promising prospect, as 12 moles of electrons would be transferred when 1 mole of Sb 2 Se 3 is used as the anode in SIBs, on basis of the general reaction, Sb 2 Se 3 + 12Na + + 12e − →2Na 3 Sb + 3Na 2 Se, and when the theoretical capacity is 670 mA h g −1. However, the Na storage