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The addition of different concentrations (2–10 wt.%) of molybdenum disulfide (MoS₂) to a poly–ether–ether–ketone matrix has been studied in terms of the thermal, mechanical and tribological properties of the materials. The results of dry-sliding tribological tests, differential scanning calorimetry and scanning electron microscope–energy-dispersive X-ray (EDS) analyses show that the concentration of MoS₂ influences the tribological, mechanical and thermal properties. With the highest concentration of MoS₂ (10 wt.%), the coefficient of friction was reduced by as much as 25%, while the maximum reduction in the wear rate was ~20%, which required 5 wt.% of MoS₂. The most important parameter when it comes to achieving an improved tribological behaviour was found to be the combination of a high hardness and a sufficient quantity of transfer film being formed. Copyright © 2015 John Wiley & Sons, Ltd.

Molybdenum disulfide (MoS₂) has received considerable interest for electrochemical energy storage and conversion. In this work, we have designed and synthesized a unique hybrid hollow structure by growing ultrathin MoS₂ nanosheets on N-doped carbon shells (denoted as C@MoS₂ nanoboxes). The N-doped carbon shells can greatly improve the conductivity of the hybrid structure and effectively prevent the aggregation of MoS₂ nanosheets. The ultrathin MoS₂ nanosheets could provide more active sites for electrochemical reactions. When evaluated as an anode material for lithium-ion batteries, these C@MoS₂ nanoboxes show high specific capacity of around 1000 mAh g⁻¹, excellent cycling stability up to 200 cycles, and superior rate performance. Moreover, they also show enhanced electrocatalytic activity for the electrochemical hydrogen evolution.

Nanosheets-on-Box: A hybrid structure composed of thin MoS₂ nanosheets supported on N-doped carbon nanoboxes has been synthesized. Because of the structural advantages, these well-defined C@MoS₂ nanoboxes exhibit superior electrochemical performance as electrode materials for both lithium-ion batteries and the hydrogen evolution reaction.

Size-dependent optical absorption of semiconductive (2H) layered molybdenum disulfide (MoS₂), exhibiting great discrimination abilities to single- and double-stranded DNA (ssDNA) and (dsDNA), is studied. In the presence of high concentration of salt, layered MoS₂ trends to aggregate rapidly, leading to the increases of sizes in both vertical and lateral dimensions of the nanosheets, which results from the interplay between van der Waals attraction and electrical double-layer repulsion. Meanwhile, the aggregation behavior of layered MoS₂ is remarkably inhibited by the synergistic effects of DNA oligonucleotides. ssDNA can adsorb on the surface of layered MoS₂, resulting in a great dispersion, even in the presence of high concentration of salt, while the dispersion behavior is weakened when ssDNA is replaced by dsDNA. Whereas compared to graphene with zero bandgap energy, layered MoS₂, with semiconductive properties, exhibits great characteristic optical absorption in visible wavelength region devoted to exploring the aggregation behavior of layered MoS₂. Therefore, DNA oligonucleotides induced size control of layered MoS₂, contributing to the regular change of its characteristic absorption in visible region, is considered a label-free bioassay for the detection of single-nucleotide polymorphism. Due to its easy operation and high specificity, it is expected that the proposed assay holds great promise for further applications.

Size-dependent optical absorption of semiconductive (2H) layered molybdenum disulfide (MoS₂), exhibiting great discriminated abilities to single- and double-stranded DNA, is explored through salt-induced aggregation of 2D nanosheets. Meanwhile, the aggregation behavior of layered MoS₂ is remarkably inhibited by the synergistic effects of DNA oligonucleotides, contributing to the developments of biosensors based on optical absorption spectrum of layered MoS₂.

A scanning probe image of single-layer MoS₂ trapping water on a mica surface is depicted on the left, with its corresponding photoluminescence image depicted on the right. The trapped water strongly quenches the fluorescence of single-layer MoS₂ and distinctly affects its optical properties. The work by J. R. Heath and co-workers on page 2734 highlights the significance of the local chemical environment in determining the opto-electronic properties of 2D materials.

3D electrodes coated with Mo_xW_1−xS₂ alloys with different Mo/W ratios are prepared. The morphology, elemental composition, and electrocatalytic properties toward hydrogen evolution reaction are studied.

Planar CH₃NH₃PbI₃ perovskite solar cells with constant 17.2% average power conversion efficiency irrespective of the scan rate are described. These properties are attributed to the formation of a pure CH₃ NH₃ PbI₃ thin film by the introduction of a HI solution. Thereby, charge-injection/separation efficiency, charge-collection efficiency, diffusion coefficient, carrier lifetime, and traps are improved.

The 2D semiconductor MoS₂ in its mono- and few-layer form is expected to have a significant exciton binding energy of several 100 meV, suggesting excitons as the primary photoexcited species. Nevertheless, even single layers show a strong photovoltaic effect and work as the active material in high sensitivity photodetectors, thus indicating efficient charge carrier photogeneration. Here, modulation spectroscopy in the sub-ps and ms time scales is used to study the photoexcitation dynamics in few-layer MoS₂. The results suggest that the primary photoexcitations are excitons that efficiently dissociate into charges with a characteristic time of 700 fs. Based on these findings, simple suggestions for the design of efficient MoS₂ photovoltaic and photodetector devices are made.

Few-layer MoS₂ flakes are intermediates between conventional semiconductors and excitonic nanomaterials. By femtosecond optical pump–probe spectroscopy it is shown that photoexcitation creates excitons as the primary species. The excitons efficiently dissociate into charge carriers with a time constant of 700 fs, making few-layer MoS₂ an excellent candidate for efficient photodetectors and photovoltaic devices.

One of the ways by which grease is evaluated is by using a four-ball wear test using ASTM D2266. However, actual applications may require bearings to be subjected to spectrum loading conditions. This study focuses on using ball milling to mitigate the wear from sharp edges in the MoS₂ particles. Two different blends of greases were formulated using MoS₂ in the as-received state (unmilled) and milled MoS₂; they were tested under spectrum loading conditions where the load and frequency of the tests were treated as variables. It was found that ball milling of the MoS₂ significantly reduces the wear under spectrum loading condition both for ramp-up and ramp-down conditions. It was also shown that shortening the time step for both the ramp-up and ramp-down cycles resulted in larger wear for unmilled MoS₂ particles in comparison with milled MoS₂ particles in grease. The milling process did not play a significant role when frequency of the test was either ramped up or down. Copyright © 2015 John Wiley & Sons, Ltd.

Crystalline defects in MoS₂ may induce midgap states, resulting in low carrier mobility. These midgap states are usually difficult to probe by conventional transport measurement. The quantum capacitance of single-layer graphene is sensitive to defect-induced states near the Dirac point, at which the density of states is extremely low. It is reported that the hexagonal-boron nitride/graphene/MoS₂ sandwich structure facilitates the exploration of the properties of those midgap states in MoS₂. Comparative results of the quantum capacitance of pristine graphene indicate the presence of several midgap states with distinct features. Some of these states donate electrons while some states lead to localization of electrons. It is believed that these midgap states originate from intrinsic point defects such as sulfur vacancies, which have a significant impact on the property of the MoS₂/graphene interface. They are responsible for the contact problems of metal/MoS­₂ interfaces.

Crystalline defects in MoS₂ may induce midgap states that are usually difficult to probe by conventional transport measurement. The quantum capacitance of single-layer graphene is sensitive to defect-induced states near the Dirac point. Therefore, it is inspiring to fabricate a hexagonal-boron nitride/graphene/MoS₂ sandwich structure to explore the electronic properties of those midgap states.

Through a combination of chemical and mutual dot-to-dot surface passivation, high-quality colloidal quantum dot solids are fabricated. The joint passivation techniques lead to a record diffusion length for colloidal quantum dots of 230 ± 20 nm. The technique is applied to create thick photovoltaic devices that exhibit high current density without losing fill factor.

Single-crystalline square microdisks of CH₃NH₃PbBr₃ are prepared by using a one-step solution self-assembly method. Single-mode lasing at 557 nm is achieved based on a built-in whispering gallery mode microresonator at room temperature. By partial replacement of Br with Cl, lasing wavelengths are continuously tuned from 525 to 557 nm.

FeSe₂ microspheres assembled by nano­octahedra are used as an anode material for Na-ion batteries for the first time, showing a high discharge capacity (447 mA h g⁻¹ at 0.1 A g⁻¹), excellent rate performance (388 mA h g⁻¹ at 5 A g⁻¹ and 226 mA h g⁻¹ at 25 A g⁻¹), and long cycling stability (372 mA h g⁻¹ after 2000 cycles at 1 A g⁻¹).

Today, the ever-increasing demand for large-size power tools has provoked worldwide competition in developing lithium-ion batteries having higher energy and power densities. In this context, advanced anode materials are being extensively pursued, among which TiO₂ is particularly promising owing to its high safety, excellent cost and environmental performances, and high cycle stability. However, TiO₂ is faced with two detrimental deficiencies, that is, extremely low theoretical capacity and conductivity. Herein, a smart hybridization strategy is proposed for the hierarchical co-assembly of TiO₂ nanorods and Fe₃O₄ nanoparticles on pristine graphene nanosheets, aiming to simultaneously address the capacity and conductivity deficiencies of TiO₂ by coupling it with high-capacity (Fe₃O₄) and high-conductivity (pristine graphene) components. The resulting novel, multifunctional ternary heterostructures effectively integrate the intriguing functionalities of the three building blocks: TiO₂ as the major active material can adequately retain such merits as high safety and cycle stability, Fe₃O₄ as the auxiliary active material can contribute extraordinarily high capacities, and pristine graphene as the conductive dopant can guarantee sufficient percolation pathways. Benefiting from a remarkable synergy, the ternary heterostructures deliver superior reversible capacities and rate capabilities, thus casting new light on developing next-generation, high-performance anode materials.

A smart hybridization strategy is proposed for the hierarchical co-assembly of TiO₂ nanorods and Fe₃O₄ nanoparticles on pristine graphene nanosheets, aiming to simultaneously address the deficiencies of TiO₂ by coupling it with high-capacity (Fe₃O₄) and high-conductivity (pristine graphene) components. Benefiting from a remarkable synergy, the resulting novel, multifunctional ternary heterostructures deliver superior reversible capacities and rate capabilities, thus casting new light on developing advanced LIB anode materials.