Temperature measurement in biology and medical diagnostics, along with sensitive temperature probing in living cells, is of great importance; however, it still faces significant challenges. Metal ...nanoclusters （NCs） with attractive luminescent properties may be promising candidates to overcome such challenges. Here, a novel one-step synthetic method is presented to prepare highly fluorescent copper NCs （CuNCs） in ambient conditions by using glutathione （GSH） as both the reducing agent and the protective layer preventing the aggregation of the as-formed NCs. The resultant CuNCs, with an average diameter of 2.3 nm, contain 1-3 atoms and exhibit red fluorescence （A~m = 610 nm） with high quantum yields （QYs, up to 5.0%）. Interestingly, the fluorescence signal of the CuNCs is reversibly responsive to the environmental temperature in the range of 15-80 ℃. Furthermore, as the CuNCs exhibit good biocompatibility, they can pervade the MC3T3-E1 cells and enable measurements over the physiological temperature range of 15-45 ℃ with the use of the confocal fluorescence imaging method. In view of the facile synthesis method and attractive fluorescence properties, the as-prepared CuNCs may be used as photoluminescence thermometers and biosensors.
A facile strategy was reported to fabricate vertically oriented and densely packed hexagonal boron nitride (h-BN)/epoxy (EP) composites via vacuum filtration followed by slicing up. This route is ...simple and high-efficient without special treatment and/or chemical modification. A high through-plane thermal conductivity of 9W/mK was obtained at a h-BN loading of 44vol% in the composites. Laser flash thermal analyzer (LFA) and thermogravimetric analysis (TGA) results indicated that the through-plane thermal conductivity of the composites increased with the fraction of the fillers. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests indicated that h-BN microplatelets were mainly vertically oriented in the composites. In addition, as-made composites showed good mechanical strength. Therefore, it has great potential as thermal interface materials, which is very important in the thermal management of electronics, especially in electronic packages where electrical insulation is required.
Two-dimensional (2D) semiconductors, in particular transition metal dichalcogenides (TMDCs), have attracted great interest in extending Moore's law beyond silicon
. However, despite extensive efforts
..., the growth of wafer-scale TMDC single crystals on scalable and industry-compatible substrates has not been well demonstrated. Here we demonstrate the epitaxial growth of 2 inch (~50 mm) monolayer molybdenum disulfide (MoS
) single crystals on a C-plane sapphire. We designed the miscut orientation towards the A axis (C/A) of sapphire, which is perpendicular to the standard substrates. Although the change of miscut orientation does not affect the epitaxial relationship, the resulting step edges break the degeneracy of nucleation energy for the antiparallel MoS
domains and lead to more than a 99% unidirectional alignment. A set of microscopies, spectroscopies and electrical measurements consistently showed that the MoS
is single crystalline and has an excellent wafer-scale uniformity. We fabricated field-effect transistors and obtained a mobility of 102.6 cm
V
s
and a saturation current of 450 μA μm
, which are among the highest for monolayer MoS
. A statistical analysis of 160 field-effect transistors over a centimetre scale showed a >94% device yield and a 15% variation in mobility. We further demonstrated the single-crystalline MoSe
on C/A sapphire. Our method offers a general and scalable route to produce TMDC single crystals towards future electronics.
Along with the technology evolution for dense integration of high-power, high-frequency devices in electronics, the accompanying interfacial heat transfer problem leads to urgent demands for advanced ...thermal interface materials (TIMs) with both high through-plane thermal conductivity and good compressibility. Most metals have satisfactory thermal conductivity but relatively high compressive modulus, and soft silicones are typically thermal insulators (0.3 W m–1 K–1). Currently, it is a great challenge to develop a soft material with the thermal conductivity up to metal level for TIM application. This study solves this problem by constructing a graphene-based microstructure composed of mainly vertical graphene and a thin cap of horizontal graphene layers on both the top and bottom sides through a mechanical machining process to manipulate the stacked architecture of conventional graphene paper. The resultant graphene monolith has an ultrahigh through-plane thermal conductivity of 143 W m–1 K–1, exceeding that of many metals, and a low compressive modulus of 0.87 MPa, comparable to that of silicones. In the actual TIM performance measurement, the system cooling efficiency with our graphene monolith as TIM is 3 times as high as that of the state-of-the-art commercial TIM, demonstrating the superior ability to solve the interfacial heat transfer issues in electronic systems.
Neutral aqueous rechargeable Co
3
O
4
//Zn batteries with high-output voltage and outstanding cycling stability have yielded new insights into wearable energy-storage devices. To meet the increasing ...demand for a means of powering wearable and portable devices, the development of a high-performance fiber-shaped Co//Zn battery would be highly desirable. However, the intrinsically poor conductivity of Co
3
O
4
significantly restricts the application of these high-capacity and high-rate aqueous rechargeable battery. Encouragingly, density functional theory (DFT) calculations demonstrate that the substitution of Zn for Co
3+
leads to an insulator-metal transition in the Zn-doped Co
3
O
4
(Zn-Co
3
O
4
). In this study, we used metallic Zn-Co
3
O
4
nanowire arrays (NWAs) as a novel binder-free cathode to successfully fabricate an all-solid-state fiber-shaped aqueous rechargeable (AFAR) Co//Zn battery. The resulting fiber-shaped Co//Zn battery takes advantage of the enhanced conductivity, increased capacity, and improved rate capability of Zn-Co
3
O
4
NWAs to yield a remarkable capacity of 1.25 mAh·cm
−2
at a current density of 0.5 mA·cm
−2
, extraordinary rate capability (60.8% capacity retention at a high current density of 20 mA·cm
−2
) and an admirable energy density of 772.6 mWh·cm
−3
. Thus, the successful construction of Zn-Co
3
O
4
NWAs provides valuable insights into the design of high-capacity and high-rate cathode materials for aqueous rechargeable high-voltage batteries.
Metal sulfide based materials as photocatalysts for energy conversion are essential to produce value-added chemical fuels, but their intrinsically slow carrier dynamics and low activity are yet to be ...resolved. Herein, we developed a unique heterogeneously nanostructured ZnIn
2
S
4
-CdS heterostructure that involves zero-dimensional (0D) CdS quantum dots uniformly confined on three-dimensional (3D) ZnIn
2
S
4
nanoflowers, which achieves an excellent catalytic performance of CO
2
photoconversion under visible-light irradiation. The obtained hierarchical heterostructure can significantly enhance the light harvesting, shorten the migration distance of carriers, and obviously accelerate the transport of electrons. As evidenced by the ultrafast transient absorption spectroscopy, the formed interface can effectively facilitate charge separation and transport. This work opens up a new avenue to carefully design the elaborate heterostructures for achieving optimal charge separation efficiency by lowering interfacial kinetic barriers and energy losses at the interface.
With the decreased sizes of microelectronic devices, the excess heat has become one of the most important factors that shorten the lifetime of electronic components. As a result, developing materials ...with high-thermal conductivity is an urgent issue. In this study, we combine an ultrasonic exfoliation and evaporated self-assembly methods to prepare boron nitride nanosheets (BNNS)/thermoplastic polyurethane (TPU) composites with small (S) and large (L) sizes connected BNNS as additives. Our results indicate that BNNS/TPU nanocomposites have better thermal conductivity than TPU, and the optimum performance is achieved at 10 wt% BNNS(S/L-1/9)/TPU. This enhanced thermal conductivity is ascribed to the successful construction of effective thermal conductive pathway. The S-BNNS is connected to the adjacent L-BNNS in TPU, which can also form a dense structure. The formation of the continuous thermal conductive pathways and networks structure facilitate the heat diffusion throughout the composites, which are the key to achieving high thermal conductivity in polymer composites. Furthermore, these results may be helpful to the deeper understanding for the combined structure of fillers in polymer matrix, which will expand the scope of applications for these materials.
Molybdenum disulfide (MoS2) nanosheets have been attracting increasing research interests due to their unique material properties. However, the lack of a reliable large‐scale production method ...impedes their practical applications. Here a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is reported. The 26.7 ± 0.7 mg/mL concentration achieved is the highest concentration in an aqueous solution reported up to now. Grinding generates pure shear forces to detach the MoS2 layers from the bulk materials. Subsequent sonication further breaks larger crystallites into smaller crystallites, which promotes the dispersion of MoS2 nanosheets in ethanol/water solutions. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution. In the meantime, MoS2‐based sensing film produced using this approach has successfully demonstrated the feasibility of a low‐cost and efficient NH3 gas sensor using inkjet printing as a viable method.
The lack of a reliable large‐scale production method inhibits practical applications of MoS2 nanosheets. To address this, a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is developed. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution.
Using the concept of “cloning”, we report herein a rational approach to grow single-walled carbon nanotubes (SWNTs) with controlled chirality via an open-end growth mechanism. Specifically, by using ...open-end SWNTs as “seeds/catalysts” (without metal catalysts), “new/duplicate” SWNTs could be grown and cloned from the parent segments via an open-end growth mechanism. Using this strategy, we have measured more than 600 short seed segments and have found that the yield of cloning is relatively low (around 9%). This yield can be greatly improved up to 40% by growing SWNTs on quartz substrate. Atomic force microscopy and micro resonance Raman spectroscopy characterization indicate that the parent nanotube and the duplicate nanotube have the same structure. These findings provide a potential approach for growing SWNTs with controlled chirality, which are important for the application of SWNTs in nanoelectronics.
Enabling fast ion diffusion in thick electrodes (100–200 µm, ~ 10 mg cm−2) is critical for their practical application in state-of-the-art supercapacitors (SCs). We developed a three-dimensional (3D) ...boron, nitrogen, and phosphorus ternary-doped holey graphene hydrogel (BNP-HGH) film to achieve an optimized porous structure with a high electrical conductivity, large ion accessible surface area, efficient electron and ion transport pathways, as well as high ion adsorption capacity. The binder-free BNP-HGH electrode can deliver a specific capacitance of 350 F g−1 and a volumetric capacity of 234 F cm−3, which are the best performance reported so far for graphene-based SCs using an organic electrolyte. Fully packaged SCs using the BNP-HGH electrodes with a commercial level graphene mass loading (150 µm, ~ 10 mg cm−2) can deliver ultrahigh stack gravimetric and volumetric energy densities of 38.5 Wh kg−1 and 57.4 Wh L−1, respectively, which are comparable to those of lead-acid batteries (35–40 Wh kg−1 and 50–90 Wh L−1) while maintaining an ultrahigh power density of 83 kW kg−1 (~ 55 kW L−1) as well as a long cycle life (81.3% capacitance retention over 50,000 cycles). The high energy and power densities bridge the gap between traditional SCs and batteries, and should be very useful in practical applications.
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•A three-dimensional ternary doped holey graphene hydrogel (BNP-HGH) film is developed.•The BNP-HGH film electrode delivers a superior capacitance of 350 F g−1 (234 F cm−3).•It exhibits ultrahigh energy density even with a high mass loading of 10 mg cm-2.•The assembled device shows an impressive stack energy density of 57.4 Wh L−1.
