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Silicon photonics with the advantages of low power consumption and low fabrication cost is a crucial technology for facilitating high-capacity optical communications and interconnects. The graphene photodetectors (GPDs) featuring broadband operation, high speed, and low integration cost can be good additions to the SiGe photodetectors, supporting high-speed photodetection in wavelength bands beyond 1.6 μm on silicon. Here we realize a silicon-integrated four-channel wavelength division multiplexing (WDM) optical receiver based on a micro-ring resonator (MRR) array and four p-n homojunction GPDs. These photo-thermoelectric (PTE) GPDs exhibit zero-bias responsivities of ∼1.1 V W−1 and set-up limited 3 dB-bandwidth >67 GHz. The GPDs show good consistence benefiting from the compact active region array (0.006 mm2) covered by a single mechanically exfoliated hBN/graphene/hBN stack. Moreover, the WDM graphene optical receiver realized 4 × 16 Gbps non-return-to-zero optical signal transmission. To the best of our knowledge, it is the first GPD-array-based optical receiver using high-quality mechanically exfoliated graphene and edge graphene-metal contacts with low resistances. Apparently, our design is also compatible with CVD-grown graphene. This work sheds light on the large-scale integration of GPDs with high consistency and uniformity, enabling the application of high-quality mechanically exfoliated graphene, and promoting the development of the graphene photonic integrated circuits. [ABSTRACT FROM AUTHOR]

The transfer of graphene from metallic substrates onto application-specific substrates is usually inevitable for the applications of high-quality graphene films derived from chemical vapour deposition (CVD) approaches. Commonly used to support the graphene films during the transfer, the coating of the polymer would produce the surface contaminations and hinder the industrially compatible transfer. In this work, through the thermal imidization of polyamide acid (PAA) to polyimide (PI) and tuning of the concentration of dangling chains, we achieved the ultraclean and crack-free transfer of graphene wafers with high electronic quality. The resulting contamination-free and hydrophilic surface also enabled the observed improved cell viability in a biomedical applications. By avoiding aqueous etching or the usage of strong bases, our proposed transfer method is industrially compatible for batch transfer of graphene films towards the real applications. [ABSTRACT FROM AUTHOR]

Graphene photodetectors have exhibited high bandwidth and capability of being integrated with silicon photonics (SiPh), holding promise for future optical communication devices. However, they usually suffer from a low photoresponsivity due to weak optical absorption. In this work, we have implemented SiPh-integrated twisted bilayer graphene (tBLG) detectors and reported a responsivity of 0.65 A W–1 for telecom wavelength 1,550 nm. The high responsivity enables a 3-dB bandwidth of >65 GHz and a high data stream rate of 50 Gbit s–1. Such high responsivity is attributed to the enhanced optical absorption, which is facilitated by van Hove singularities in the band structure of high-mobility tBLG with 4.1o twist angle. The uniform performance of the fabricated photodetector arrays demonstrates a fascinating prospect of large-area tBLG as a material candidate for heterogeneous integration with SiPh. Silicon-integrated graphene photodetectors exhibit promising bandwidths at telecom wavelengths, but their responsivity is usually limited. Here, the authors report the wafer-scale fabrication of waveguide-integrated detectors based on twisted bilayer graphene, showing responsivities up to 0.65 A/W and 3-dB bandwidths >65 GHz. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) nanospheres, nanofibers, and nanoplates were prepared using the oxidative polymerization method. Scanning electron microscopy (SEM) was used to observe the three morphologies of PANI, and their structure was tested using infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The influence of particle morphology on the electrorheological (ER) effect was studied through rheological experiments and molecular dynamics (MD) simulation. The experimental and simulation results indicate that without applying an electric field, the nanofibers easily form a three-dimensional network structure in the suspension, resulting in yield stress. The three-dimensional network structure of the nanoplate suspension becomes weaker and the PANI nanosphere suspension lacks the ability to form a three-dimensional network structure. After applying an electric field, under the same condition, the yield stress and electric field-induced shear stress increment of PANI nanofibers are the highest, followed by nanoplates, and those of PANI nanospheres are the lowest. This indicates that the ER effect increases with the increase in particle morphology anisotropy. Through three-dimensional visual simulation analysis, it can be concluded that the enhanced ER effect associated with increased particle anisotropy can be attributed to improved stability in the ER chain structure. [ABSTRACT FROM AUTHOR]

Electrorheological polishing (ERP) is an important field-assisted polishing method, which can reduce abrasive loss and improve machining efficiency by using the electric field-induced electrorheological (ER) effect to help the abrasive to overcome the centrifugal force caused by high rotating speed during polishing. ERP has many advantages, including high efficiency, high precision, facile polishing for a small object, and a good application prospect in polishing optical devices and hard molds. This review describes the research progress in ERP in the past two decades. The mechanism of electrorheological polishing is analyzed from two aspects of electrorheological effect and dielectrophoresis. According to the time sequence of electrorheological polishing development, two kinds of ERP materials including the simple mixing system and composite particle system are introduced. ERP electrodes including off-axis bipolar electrode, needle-ring electrode, needle-like single electrode, one-sided patterned electrode, and one-sided simple composite electrode are described. From the two characterization quantities of removal rate and surface quality, the industrial factors affecting the ERP effect are discussed. The advantages and disadvantages of ERP and other polishing processes are compared. Finally, the remaining challenges and possible development trends in ERP technology for the future outlook are proposed. [ABSTRACT FROM AUTHOR]

Electrorheological (ER) polishing is a novel polishing technology having flexible and tunable characteristics. At present, ER polishing uses ER particles to drive abrasive particles to polish the material surface. Under the action of high-speed centrifugation, the abrasive particles are easily separated from ER particles due to their significantly different ER effect, and this can easily cause the degradation of polishing ability. In this work, alumina-doped titanium dioxide ER polishing particles were developed via a sol-gel method. As a classical abrasive, alumina has higher hardness and can improve the ER effect of titanium dioxide by doping. Thus, alumina-doped titanium dioxide particles simultaneously possess high ER effect and high hardness. No phase separation appears in the polishing process and the result shows that alumina-doped titanium dioxide has a good polishing efficiency for materials with Mohs hardness of 3 and below. [ABSTRACT FROM AUTHOR]

The electronic structures and optical properties of cubic C3N4 doped by vanadium (V) were investigated by first principles. The calculation results of the electronic structure show that V-doped cubic C3N4 can produce two intermediate bands around the Fermi level. The calculation results of the optical properties show that V doping can significantly increase the light absorption of cubic C3N4 in UV–visible region. Therefore, the overall calculated results show that V-doped cubic C3N4 can produce new intermediate band structures and improve the optical performance of the material. [ABSTRACT FROM AUTHOR]

Radiative thermal management has attracted increasing attention for the advantages of energy saving and carbon emission reduction. Infrared radiation coatings are widely adopted to alleviate the low infrared emissivity of commonly used metal alloy electrothermal materials. However, traditional infrared radiation coatings are faced with the issues of the unsteady waveband emissivity, low interfacial adhesion to substrates, and poor long‐term thermal stability. Herein, a bush‐shaped vertical graphene (BVG) grown on nichrome (Ni–Cr) wire is demonstrated, relying on which BVG/Ni–Cr wire presents a high blackbody‐like emissivity of ≈0.96 across a wide wavelength range (2.5–18 µm). When used for radiative heating, BVG/Ni–Cr wire achieves a high thermal radiation efficiency with an order of magnitude improvement compared with bare Ni–Cr wire, as well as the superior deformation and thermal stabilities. These findings reveal the impressive potentials of BVG as an excellent infrared radiation material for the energy‐efficient radiative thermal management. [ABSTRACT FROM AUTHOR]

Programmability, fundamental to the computing of electronic systems, is traditionally achieved in processing and memory modules. Recently, the emergence of in‐sensor computing allows the programmability of the sensing modules and the process of raw data upon the sensor edge, which reduces data transport and energy consumption. Here, a programmable photodetector module with a tunable photoelectric response based on molybdenum sulfide (MoS2) metal‐oxide‐semiconductor (MOS) junction for visible detection is reported. The sensor takes advantage of the tunable band alignment at the MOS junction and generates an adjustable or even reversible out‐of‐plane photovoltaic effect with high efficiency. This work provides new device configurations to architect the programmability of the photodetectors, and pave the way toward in‐sensor computing at the application edge. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition (CVD) has emerged as a promising approach for the controlled growth of graphene films with appealing scalability, controllability, and uniformity. However, the synthesis of high-quality graphene films still suffers from low production capacity and high energy consumption in the conventional hot-wall CVD system. In contrast, owing to the different heating mode, cold-wall CVD (CW-CVD) system exhibits promising potential for the industrial-scale production, but the quality of as-received graphene remains inferior with limited domain size and high defect density. Herein, we demonstrated an efficient method for the batch synthesis of high-quality graphene films with millimeter-sized domains based on CW-CVD system. With reduced defect density and improved properties, the as-received graphene was proven to be promising candidate material for electronics and anti-corrosion application. This study provides a new insight into the quality improvement of graphene derived from CW-CVD system, and paves a new avenue for the industrial production of high-quality graphene films for potential commercial applications. [ABSTRACT FROM AUTHOR]

Cu wires (CuWs) are widely used as electric transmission lines. However, their limited thermal and chemical stabilities become challenges under the high-power and harsh environment. Graphene is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and molecules. Particularly, the excellent hydrophobicity of vertical graphene (VG) will strengthen its protective capability as a corrosion and oxidation barrier. Herein, VG is directly synthesized on CuW by plasma-enhanced chemical vapor deposition method. The hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further penetration. Consequently, the electrochemical corrosion rate of VG-CuW is reduced by ∼ 13, 8, and 2 times, compared with bare CuW, VG-CuW with hydrophilic treatment, and CuW coated with thick horizontal graphene layers, respectively. Negligible oxidation occurs on VG-CuW after the long-time exposure to humid air at ∼ 200 °C along with the largely enhanced tolerance under high-current operating condition. This study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment. [ABSTRACT FROM AUTHOR]

The integration of large-scale two-dimensional (2D) materials onto semiconductor wafers is highly desirable for advanced electronic devices, but challenges such as transfer-related crack, contamination, wrinkle and doping remain. Here, we developed a generic method by gradient surface energy modulation, leading to a reliable adhesion and release of graphene onto target wafers. The as-obtained wafer-scale graphene exhibited a damage-free, clean, and ultra-flat surface with negligible doping, resulting in uniform sheet resistance with only ~6% deviation. The as-transferred graphene on SiO2/Si exhibited high carrier mobility reaching up ~10,000 cm2 V−1 s−1, with quantum Hall effect (QHE) observed at room temperature. Fractional quantum Hall effect (FQHE) appeared at 1.7 K after encapsulation by h-BN, yielding ultra-high mobility of ~280,000 cm2 V−1 s−1. Integrated wafer-scale graphene thermal emitters exhibited significant broadband emission in near-infrared (NIR) spectrum. Overall, the proposed methodology is promising for future integration of wafer-scale 2D materials in advanced electronics and optoelectronics. Defect-free integration of 2D materials onto semiconductor wafers is desired to implement heterogeneous electronic devices. Here, the authors report a method to transfer high-quality graphene on target wafers via gradient surface energy modulation, leading to improved structural and electronic properties. [ABSTRACT FROM AUTHOR]

Intelligent materials with adaptive response to external stimulation lay foundation to integrate functional systems at the material level. Here, with experimental observation and numerical simulation, we report a delicate nano-electro-mechanical-opto-system naturally embedded in individual multiwall tungsten disulfide nanotubes, which generates a distinct form of in-plane van der Waals sliding ferroelectricity from the unique combination of superlubricity and piezoelectricity. The sliding ferroelectricity enables programmable photovoltaic effect using the multiwall tungsten disulfide nanotube as photovoltaic random-access memory. A complete "four-in-one" artificial vision system that synchronously achieves full functions of detecting, processing, memorizing, and powering is integrated into the nanotube devices. Both labeled supervised learning and unlabeled reinforcement learning algorithms are executable in the artificial vision system to achieve self-driven image recognition. This work provides a distinct strategy to create ferroelectricity in van der Waals materials, and demonstrates how intelligent materials can push electronic system integration at the material level. Intelligent materials change their properties under external stimuli, integrating functionalities at the matter level. Here, Guo et al. report an artificial vision system based on the memory effect produced by sliding ferroelectricity in multiwalled tungsten disulfide nanotubes. [ABSTRACT FROM AUTHOR]

Microalgal lipids are essential for biofuel and dietary supplement production. Lipid engineering for higher production has been studied for years. However, due to the complexity of lipid metabolism, single-gene engineering gradually encounters bottlenecks. Multiple gene regulation is more beneficial to boosting lipid accumulation and further clarifying the complex regulatory mechanism of lipid biosynthesis in the homeostasis of lipids, carbohydrates, and protein metabolism. Here, three lipid-related genes, DOF, LACS2, and CIS, were co-regulated in Chlamydomonas reinhartii by two circles of transformation to overexpress DOF and knock down LACS2 and CIS simultaneously. With the multiple regulations of these genes, the intracellular lipids and FA content increased by 142% and 52%, respectively, compared with CC849, whereas the starch and protein contents decreased by 45% and 24%. Transcriptomic analysis showed that genes in TAG and FA biosynthesis were up-regulated, and genes in starch and protein metabolism were down-regulated. This revealed that more carbon precursor fluxes from starch and protein metabolism were redirected towards lipid synthesis pathways. These results showed that regulating genes in various metabolisms contributed to carbon flux redirection and significantly improved intracellular lipids, demonstrating the potential of multiple gene regulation strategies and providing possible candidates for lipid overproduction in microalgae. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Waveguide-integrated twisted bilayer graphene photodetectors" published in Nature Communications. The correction addresses an error in the Methods section of the original article, where the chemical formula (NH4)2S2O8 was mistakenly written as (NH)4S2O8. The correction has been made in both the PDF and HTML versions of the article. The authors who contributed equally to the article are Qinci Wu, Jun Qian, Yuechen Wang, and Luwen Xing, along with several other authors listed in the document. [Extracted from the article]

Urchin-like microparticles/nanoparticles assembled from radial nanorods have a good appearance and high specific surface area, providing more exposed active sites and shortening the diffusion path of photoexcited carriers from the interior to the surface. The interfacial interaction and physical and chemical properties of the materials can be improved by the interfacial porous network induced by interlacing nano-branches. In addition, multiple reflections of the layered microstructure can absorb more incident light and improve the photocatalytic performance. Therefore, the synthesis and functionalization of three-dimensional urchin-like nanostructures with controllable size, shape, and hierarchy have attracted extensive attention. This review aims to provide an overview to summarize the structures, mechanism, and application of urchin-like microparticles/nanoparticles derived from diverse synthesis methods and decoration types. Firstly, the synthesis methods of solid urchin-like micro-/nanoparticles are listed, with emphasis on the hydrothermal/solvothermal method and the reaction mechanism of several typical examples. Subsequently, the preparation method of composite urchin-like micro-/nanoparticles is described from the perspective of coating and doping. Then, the research progress of urchin-like hollow microspheres is reviewed from the perspective of the step-by-step method and synchronous method, and the formation mechanism of forming urchin-like hollow microspheres is discussed. Finally, the application progress of sea urchin-like particles in the fields of photocatalysis, electrochemistry, electromagnetic wave absorption, electrorheological, and gas sensors is summarized. [ABSTRACT FROM AUTHOR]

A simple preparation of inorganic reinforced poly(ionic liquid) (PIL) microcapsules by combining dispersion polymerization and confined cooling‐assisted phase separation self‐assembly is reported. Silane coupling agent‐modified PIL microbeads are first prepared by dispersion polymerization. Then, the microbeads are dissolved in a theta solvent composed of good solvent and non‐solvent to form hollow SiOx microcapsules at a relatively high temperature. Finally, the solution is cooled to induce the nucleation and growth of dissolved PIL chains on the inner and outer surface of hollow SiOx microcapsules to form inorganic reinforced microcapsules with asymmetric PIL/SiOx/PIL sandwich‐like shell. The morphology of microcapsules can be controlled by adjusting PIL concentration and cooling rate. The inorganic reinforced microcapsules show enhanced suspended stability and electroresponsive characteristic when used as the dispersed phase of smart suspensions. [ABSTRACT FROM AUTHOR]

The authors reported a simple and high‐yield evaporation‐assisted phase separation (EAPS) method to prepare poly(ionic liquid) (PIL) microbeads, in particular submicron microbeads. Irregular PIL powder or bulk is dissolved in a theta solvent composed of volatile good solvent and less volatile non‐solvent at room temperature, and then PIL microbeads are formed by evaporation of the solution at a temperature lower than the boiling point of volatile good solvent. The yield of microbeads, in particular, submicron microbeads, prepared by the EAPS method can reach 99%. The mechanism of microbead formation is studied by tracing the nucleation and growth process by the light transmittance. The key parameters to control the size and morphology of microbeads are investigated and discussed. [ABSTRACT FROM AUTHOR]

A simple and large‐scale non‐chemical preparation of uniform poly(ionic liquid) (PIL) microbeads via a cooling‐assisted phase separation (CAPS) method is reported. For this method, PIL bulk is dissolved to form a saturated solution in a mixed solvent composed of good solvent and non‐solvent at a relatively high temperature. Then, the uniform PIL microbeads are prepared by cooling the solution to room temperature or a lower temperature in the absence of stabilizer. The size of microbeads can be controlled by adjusting the preparation parameters, including PIL concentration, cooling rate, and agitation state. The scale of preparation can be up to 10 g, and the yield of PIL microbeads is more than 70% or 88% when the solution is cooled to room temperature or 0 °C, respectively. The formation mechanism of PIL microbeads is discussed by tracing the nucleation and growth process by the transmittance of light of the solution during cooling. The application of this CAPS method to other polymer microbeads preparation is finally discussed by choosing different good solvent and non‐solvent. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots are promising photoactive materials that enable plentiful photonic and optoelectronic applications ranging from lasers, displays and photodetectors to solar cells1–9. However, these applications mainly utilize the linear optical properties of quantum dots, and their great potential in the broad nonlinear optical regime is still waiting for full exploration10–12. Here, we demonstrate that a simple coating of a sub-200-nm-thick quantum dot film on two-dimensional materials can significantly enhance their nonlinear optical responses (second, third and fourth harmonic generation) by more than three orders of magnitude. Systematic experimental results indicate that this enhancement is driven by a non-trivial mechanism of multiphoton-excitation resonance energy transfer, where the quantum dots directly deliver their strongly absorbed multiphoton energy to the adjacent two-dimensional materials by a remote dipole–dipole coupling. Our findings could expand the applications of quantum dots in many exciting areas beyond linear optics, such as nonlinear optical signal processing, multiphoton imaging and ultracompact nonlinear optical elements. A simple coating of a sub-200-nm-thick quantum dot film on two-dimensional materials can drastically enhance their nonlinear optical responses through nonlinear-excitation resonance energy transfer by a high-efficiency remote dipole–dipole coupling. [ABSTRACT FROM AUTHOR]

Effective and selective removal of radioactive metal ions from aqueous solutions is of great importance due to their harmful effects on humans and other living species. However, it is a big challenge for researchers to develop effective adsorbents with high selectivity and a wide pH application range even if some progress has been achieved. Herein, we report an anionic potassium organic framework (UPC-K1) with protonated dimethylamine (Me2NH2+) residing inside the rhomboid channels. The unique 3D firm structure of UPC-K1 is constructed by the cross-linking of the 2D arrangement using weak K–O bonds (2.9270 Å) and strong hydrogen bonds (1.6498 Å), which endows it with excellent chemical stability in organic solvents, boiling water, and aqueous solution in the pH range 3–10. Based on the cation exchange, depending on pore size selectivity, UPC-K1 shows excellent adsorption performance towards UO22+ in aqueous solutions at 298 K with the following characteristics: (1) effective removal in the pH range 3–10; (2) high selectivity over other metal cations; (3) a high adsorption capacity of 551.4 mg g−1; (4) a rapid adsorption equilibrium within 3 hours under stirring; and (5) effective adsorption at low concentrations, with a residual concentration of 0.69 ppm even at an initial concentration of 10.3 ppm after stirring for 24 hours. These results indicate the great potential of UPC-K1 in the treatment of uranium-containing nuclear wastewater. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded organic frameworks (HOFs), similar to their MOF analogues, exhibit great potential in proton conduction applications. Herein, a porous HOF namely [(NiH4TPPP)(Me2NH2)4(DMF)(H2O)4] (UPC-H5) was synthesized from phosphonate-based porphyrinato nickel (NiH8TPPP), and its proton conductivity is regulated through a two-step guest change. Firstly, immersing UPC-H5 in CH2Cl2 to exchange lattice solvent molecules for 24 h followed by heating under vacuum afforded the lattice solvent molecule-free HOF [(NiH4TPPP)(Me2NH2)4] (UPC-H5a) with the pristine framework still retained. Secondly, exposing UPC-H5a to vapors of 25% aqueous ammonia for 24 h at room temperature gave a new derivative UPC-H5a@NH3·H2O with the molecular formula [(NiH4TPPP)(Me2NH2)2(NH4)2(H2O)4] according to elemental and thermal analyses. At 30 °C and 95% R.H., the proton conductivity of UPC-H5, UPC-H5a, and UPC-H5a@NH3·H2O amounts to 5.59 × 10−4, 7.00 × 10−3, and 1.47 × 10−2 S cm−1, respectively, which increases to 1.85 × 10−3, 3.42 × 10−2, and 1.59 × 10−1 S cm−1 at 80 °C and 99% R.H., clearly showing the effect of guest regulation on the proton conductivity of the HOF-based materials. In addition, this result is also helpful towards understanding the important role of guests in the formation of their proton conduction pathways. [ABSTRACT FROM AUTHOR]

We report the cyclic single-crystal-to-single-crystal transformation of three hydrogen-bonded organic frameworks (HOFs), induced by the change of temperature and humidity, which clearly reveals that the –SO3−and –NH2 groups in UPC-H7 and UPC-H8 facilitate the diffusion of water molecules into their anhydrous structures to form hydrous UPC-H9. Their proton conductivity was studied under different humidity at varying temperature, showing that the proton conductivity is closely related to water molecules entering the crystal structures arising from the hydrogen bonded reorganization in combination with the triaxial single-crystal proton conductivity tests. [ABSTRACT FROM AUTHOR]

ε-[Al13O4(OH)24(H2O)12]7+, which shares similarity with the phosphotriesterase active site ZnII–OH–ZnII, was specially chosen to interact with the cluster α-PMo10V2O405− to form a new three-dimensional intercluster, which crystallized in the monoclinic space group P21/m with Z = 2, for the decontamination of chemical warfare agents. The experimental results showed that 50 mg of the compound decontaminated 96.4% (within 120 min) and 99.5% (within 40 min) of sulfur mustard (HD) (4 μL) and soman (GD) (4 μL), respectively, in ambient conditions. The decontamination processes followed first-order reaction kinetics with a rate constant and half-life of 0.01234 min−1 and 56.15 min for HD and 0.1198 min−1 and 5.78 min for GD, respectively. It was concluded that the α-PMo10V2O405− moiety was responsible for the catalytic oxidation of HD into non-toxic sulfoxide, while the ε-[Al13O4(OH)24(H2O)12]7+ moiety was responsible for the catalytic hydrolysis of HD and GD into nontoxic hydrolysates. Besides, the compound showed notable efficacy for the decontamination of HD on guinea pig skin and of GD on Kunming mouse skin, indicating high potential for use in human skin protection and treatment. [ABSTRACT FROM AUTHOR]

We report the development of a new type of organic semiconductor gas sensor based on a porphyrin-based hydrogen-bonded organic framework (HOF). Owing to the orderly porous structures, the decoration with rich amino sites and the n-type semiconductor nature, this HOF-based sensor exhibits selective NO2 sensing performance with ultra-fast response/recovery rates (17.6 s/15.4 s over 100 ppb) and a limit of detection lower than 40 ppb, together with high sensitivity, good reproducibility, and long-term stability at room temperature. This study demonstrates that HOF-based materials have potential application prospects in gas sensing, thereby offering a new way of thinking for the design and development of sensors. [ABSTRACT FROM AUTHOR]

Monodisperse hydrolysis-resistant yttrium alkoxide with a rhombic dodecahedral morphology has been prepared via a facile hydrothermal method. The amount of NaOH and the volume ratio of ethylene glycol/water are key factors, which dominate the formation of rhombic dodecahedral yttrium alkoxide and its morphology. [ABSTRACT FROM AUTHOR]

The anisotropic two-dimensional (2D) layered material rhenium disulfide (ReSe) has attracted considerable attention because of its unusual properties and promising applications in electronic and optoelectronic devices. However, because of its low lattice symmetry and interlayer decoupling, anisotropic growth and out-of-plane growth occur easily, yielding thick flakes, dendritic structure, or flower-like structure. In this study, we demonstrated a bottom-up method for the controlled and scalable synthesis of ReSe by van der Waals epitaxy. To achieve controllable growth, a micro-reactor with a confined reaction space was constructed by stacking two mica substrates in the chemical vapor deposition system. Within the confined reaction space, the nucleation density and growth rate of ReSe were significantly reduced, favoring the large-area synthesis of ReSe with a uniform monolayer thickness. The morphological evolution of ReSe with growth temperature indicated that the anisotropic growth was suppressed at a low growth temperature (<600 °C). Field-effect transistors employing the grown ReSe exhibited p-type conduction with a current ON/OFF ratio up to 10 and a hole carrier mobility of 0.98 cm/(V·s). Furthermore, the ReSe device exhibited an outstanding photoresponse to near-infrared light, with responsivity up to 8.4 and 5.1 A/W for 850- and 940-nm light, respectively. This work not only promotes the large-scale application of ReSe in high-performance electronic devices but also clarifies the growth mechanism of low-lattice symmetry 2D materials. [ABSTRACT FROM AUTHOR]

Transferring MoS films from growth substrates onto target substrates is a critical issue for their practical applications. Moreover, it remains a great challenge to avoid sample degradation and substrate destruction, because the current transfer method inevitably employs a wet chemical etching process. We developed an etching-free transfer method for transferring MoS films onto arbitrary substrates by using ultrasonication. Briefly, the collapse of ultrasonication-generated microbubbles at the interface between polymer-coated MoS film and substrates induce sufficient force to delaminate the MoS films. Using this method, the MoS films can be transferred from all substrates (silica, mica, strontium titanate, and sapphire) and retains the original sample morphology and quality. This method guarantees a simple transfer process and allows the reuse of growth substrates, without involving any hazardous etchants. The etching-free transfer method is likely to promote broad applications of MoS in photodetectors. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Not only the polarizability but also the polarization rate of particles is important to the electro-responsive electrorheological (ER) characteristic of particle suspensions. In this paper, we respectively used non-conducting graphene oxide (GO) and conducting reduced graphene oxide (r-GO) as the core and use insulating SiO2 as the shell to prepare core/shell-structured dielectric nanoplates for the purpose of achieving an optimum ER response to different electric stimuli. The morphology and structure of the samples are characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and X-ray photoelectronic spectroscopy. The conductivity and dielectric properties are measured by an impedance analyzer and the electro-responsive ER characteristics of nanoplates dispersed in insulating oil are investigated by a rheometer. These demonstrate that coating with SiO2 can provide an electrical insulating effect for the GO or r-GO core, while GO vs. r-GO as the core can induce distinctly different dielectric polarization responses. Compared to GO/SiO2, r-GO/SiO2 shows a significantly faster polarization rate due to the high conductivity of the r-GO core. As a result, the r-GO/SiO2 suspension exhibits a high ER response to high-frequency AC electric fields, while the GO/SiO2 suspension exhibits a high ER response to DC or low-frequency AC electric fields. This different electro-responsive characteristic can be explained by the influence of the polarization rate on interparticle interaction. [ABSTRACT FROM AUTHOR]

To combine the advantages of a conducting graphene nanosheet (GNS) and insulating layered inorganic, we used a simple one-pot hydrothermal method to prepare two-dimensional dielectric nanoplates composed of a GNS/Mg–Al layered double-hydroxide (GNS/LDH) composite for use as a novel anisotropic electro-responsive electrorheological (ER) material. The structures of the samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. The conductivity and dielectric properties were measured by an impedance analyzer, and the electro-responsive ER characteristic of the GNS/LDH composite dispersed in insulating oil was characterized by a rheometer. The results demonstrate that the LDH can provide an electrically insulating effect for GNS, while the incorporation of the conducting GNS can enhance the dielectric polarization of LDH. The GNS/LDH composite shows a significantly stronger ER effect compared to the pure LDH, especially under AC electric fields due to the enhanced polarization response. [ABSTRACT FROM AUTHOR]

Hydrophobic poly(ionic liquid) particles are synthesized by a microwave-assisted dispersion polymerization method and their electro-responsive characteristic is investigated as a new water-free polyelectrolyte-based electrorheological (ER) system. Structure characterization shows that the poly(ionic liquid) particles are uniform microspheres with a narrow size distribution of ~1.8 μm and a low density of ~1.62 gcm[sup -3]. Under electric fields, the fluid of poly(ionic liquid) particles in silicone oil shows low current density but high ER activity including small off-field viscosity, large field-induced shear stress and storage modulus, and stable flow curves in a wide shear rate region. The ER effect increases with particle content. The typical shear stress is ~2500 Pa at 4 kV mm[sup -1] and 100 s[sup -1], which is ~30 times as high as the off-field shear stress. Dielectric spectra analysis indicates that the high ER activity can be attributed to strong dielectric polarizability and adequate polarization response induced by the high-density of cation/anion parts in poly(ionic liquid) particles. The ER activity also depends on the type of cation/anion parts. [ABSTRACT FROM AUTHOR]

For the first time we fabricated ZnO membranes with thicknesses of 2.4 nm by a facile one-pot synthesis in aqueous solution. The crystal analysis revealed that the hexagonal ZnO membranes were about 10 atomic layers in thickness. The ZnO membranes bent, scrolled, intersected with each other, and self-assembled to particles in micrometre size. The hierarchical assemblies showed sponge-like structures with room inside. In the growth process, a cationic polyelectrolyte was utilized to modulate growth behavior of the ZnO crystals. As a result, the preferred growth direction of ZnO membranes is along $$\left\langle {01 \bar 10} \right\rangle$$, which was perpendicular to [0001] growth direction in a typical hydrothermal synthesis. The growth mechanism of the membranes was also discussed. [ABSTRACT FROM AUTHOR]

Electric field-induced particle polarization is essential to the electro-responsive electrorheological (ER) effect of particle suspensions. In this work, we use graphene oxide (GO) as a soft and polar coating shell to prepare GO-wrapped titania dielectric microspheres for use as the dispersal phase of an ER suspension. Under a DC electric field, the ER characteristic of GO-wrapped titania microspheres dispersed in silicone oil is investigated by rheological tests, and then compared with that of a suspension of bare titania microspheres. The results show that the suspension of GO-wrapped titania microspheres possesses an enhanced ER characteristic. Its field-induced shear yield stress and storage modulus are much higher than those of the suspension of bare titania microspheres. The soft and polar GO shell is regarded as the origin of the ER enhancement. Dielectric analysis indicates that wrapping GO can enhance the interfacial polarization and thus improve the ER characteristics of titania microspheres. Wrapping GO onto the surface of titania microspheres can also reduce the particle sedimentation velocity of the suspension. [ABSTRACT FROM AUTHOR]

Front Cover: In article number 2100379 by Jianbo Yin and co‐workers, a facile and high yield evaporation‐assisted phase separation method to prepare uniform PIL microbeads is reported. No stabilizer is used and the size of microbeads can be easily controlled by initial PIL/H2O mass ratio, liquid level height, and evaporation temperature. [ABSTRACT FROM AUTHOR]

No stabilizer is used and the size of microbeads can be easily controlled by initial PIL/H SB 2 sb O mass ratio, liquid level height, and evaporation temperature. B Front Cover b : In article number 2100379 by Jianbo Yin and co-workers, a facile and high yield evaporation-assisted phase separation method to prepare uniform PIL microbeads is reported. Preparation of Poly(Ionic Liquid) Microbeads by Evaporation-Assisted Phase Separation. [Extracted from the article]

Vertically oriented graphene (VG), owing to its sharp edges, non-stacking morphology, and high surface-to-volume ratio structure, is promising as a consummate material for the application of photoelectric detection. However, owing to high defect and fast photocarrier recombination, VG-absorption-based detectors inherently suffer from poor responsivity, severely limiting their viability for light detection. Herein, we report a high-performance photodetector based on a VG/indium tin oxide (ITO) composite structure, where the VG layer serves as the light absorption layer while ITO works as the carrier conduction channel, thus achieving the broadband and high response nature of a photodetector. Under the illumination of infrared light, photoinduced carriers generated in VG could transfer to the floating ITO layer, which makes them separate and diffuse to electrodes quickly, finally realizing large photocurrent detectivity. This kind of composite structure photodetector possesses a room temperature photoresponsivity as high as ~0.7 A/W at a wavelength of 980 nm, and it still maintains an acceptable performance at temperatures as low as 87 K. In addition, a response time of 5.8 s is observed, ~10 s faster than VG photodetectors. Owing to the unique three-dimensional morphology structure of the as-prepared VG, the photoresponsivity of the VG/ITO composite photodetector also presented selectivity of incidence angles. These findings demonstrate that our novel composite structure VG device is attractive and promising in highly sensitive, fast, and broadband photodetection technology. [ABSTRACT FROM AUTHOR]