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Membrane-based separation is an appealing solution to mitigate CO2 emission sustainably due to its energy efficiency and environmental friendliness. Attributed to its excellent separation endowed by nanomaterial incorporation, nanocomposite membrane is rigorously developed. This study explored the feasibility of boron nitride (BN) embedment and changes to formation mechanism of ultrathin selective layer of thin film nanocomposite (TFN) are investigated. The effects of amine-functionalization on nanosheet-polymer interaction and CO2 separation performance are also identified. Participation of nanosheets during interfacial polymerization reduced the crosslinking of selective layer, hence, improved TFN permeance while the formation of contorted diffusion paths by the nanosheets favors transport of small gases. Amine-functionalization enhanced the nanosheet-polymer interaction and elevated the membrane affinity towards CO2 which led to enhanced CO2 selectivity. The best TFN prepared in this study exhibited 37% and 20% increment in permeability and selectivity, respectively with respect to neat thin film composite (TFC). It is found that the CO2 separation performance of BN incorporated TFN is on par with many non-porous nanosheet-incorporated TFNs reported in literatures. The transport and barrier effects of BN and functionalized BN are discussed in detail to provide further insights into the development of commercially attractive CO2 selective TFN membranes.

Molecularly thin two-dimensional (2D) nanomaterials are attractive building blocks for constructing anticorrosion nanocoatings as an ultimate pursuit in the metal-related industry. However, the nanocoating of prefocused graphene is far from industrial demands due to its high cost, low scalability, and insufficient quality. We propose all requirements to realize rational anticorrosion nanocoating of metal oxide nanosheets. The proof-of-concept study with Ti0.87O2 and Ca2Nb3O10 nanosheets demonstrates that the 10 and 20 nm thick coatings fabricated by a facile layer-by-layer (LbL) self-assembly on stainless steel (SUS) give perfect inhibition efficiency (IE) values of 99.92% and 99.89%, respectively. A driving test with a nanosheet-coated car-baffle demonstrated suitable corrosion resistance and mechanical and thermal robustness for industrial applications. The revealed and controlled thermal oxidation mechanisms are critical toward high-temperature application of the 2D oxide anticorrosion nanocoating. The advantages of nanosheet coating and extensible materials design will open a solid but exciting route to anticorrosion nanotechnology.

Electrochemical (EC) reduction of graphene oxide (GO) serves as a green chemistry pathway to produce reduced GO (rGO). However, the mechanistic understanding of this process is still limited due to the structural complexity of GO-based materials. In the present study, we employ an inductive approach that consists of investigating the structures afforded by alternating EC reduction and oxidation steps to elucidate the electrochemical reduction reactions in aqueous solution. The initial EC reduction of chemically derived GO mainly converts epoxides (C–O–C) to COH/CH pairs. Simultaneously, carbon-centered radicals (C•) are eliminated. Subsequent EC oxidation does not result in restoration of epoxides but reverse dehydrogenation and radical formation. The second EC reduction and oxidation cycle involves reversible C–H formation coupled with radical elimination, suggesting that C• serves as an active site for the hydrogenation. As a result of this study, COH–CH is revealed as a plausible characteristic structure in electrochemically derived rGO. The reversible radical hydrogenation reaction can offer an effective route to manipulate the chemical reactivities of GO-based materials. We demonstrate that the electrons transferred by EC reduction can delocalize in the rGO to some extent, activating the pseudocapacitance that probably originates from COH.

Efficient electrocatalysts are highly demanded for oxygen evolution reaction (OER) in water splitting and metal–air batteries. Here, superlattice structured materials composed of CoNiFe layered dou...

Molecularly thin two-dimensional (2D) semiconductors are emerging as photocatalysts owing to their layer-number-dependent quantum effects and high charge separation efficiency. However, the correlation among the dimensionality, crystallinity, and photocatalytic activity of such 2D nanomaterials remains unclear. Herein, a Ag photoreduction technique coupled with microscopic analyses is employed to spatially resolve the photocatalytic activity of MoS2 as a model catalyst. Interestingly, we find that only monolayer (1L)-MoS2 is active for a Ag photoreduction reaction. The photocatalytic activity of 1L-MoS2 is enhanced by a built-in electrical field originated from the MoS2/SiO2 interface, instead of by the specific surface structure and quantum electronic state of 1L-MoS2. Furthermore, we observe photocatalytic active sites to be geometrically distributed on triangular 1L-MoS2 crystals, wherein the Ag particles are preferentially deposited on the outermost zigzag edges and defective inner parts of the triangular grains. The degradation of photocatalytic activity and electron mobility with the formation of Mo(VI) species indicates that the species inhibit the in-plane diffusion of the photogenerated electrons to the reductive sites. The monolayer-selectivity, activation, and inactivation mechanisms, unveiled in this work, will offer future directions in designing 2D nanophotocatalysts.

A fluorescent dye-labeled DNA probe was adsorbed and quenched on the monolayer of RuO2 nanosheets. Significant fluorescent recovery was observed upon the addition of complementary DNA due to desorption of the probe from the surface of the RuO2 nanosheet through duplex formation. The efficiency of fluorescence recovery was higher than that for graphene oxide, which was known as a quencher-free platform for the detection of nucleic acids in a homogeneous solution.

Atomic interfacial electric fields hold great potential for boosting ionic and charge transfer and accelerating electrochemical reaction kinetics. Here, built-in electric fields within the heterostructure are created by electrostatic assembly of unilamellar titano-niobate/graphene (reduced graphene oxide) nanosheets as building blocks. Scanning Kelvin probe microscopy confirms the existence of built-in electric fields by detecting the unbalanced surface potential of disparate nanosheets in the heterostructure, which facilitates ion and electron transfer, thus enabling an excellent reversible sodium storage capacity of 245 mAh g

Heterostructures of two-dimensional (2D) atomic crystals provide fascinating molecular-scale design elements for emergent physical phenomena and functional materials, as integrating distinct monolayers into vertical heterostructures can afford coupling between disparate properties. However, the available examples have been limited to either van der Waals (vdW) or electrostatic (ES) heterostructures that are solely composed of noncharged and charged monolayers, respectively. Here, we propose a "vdW-ES heterostructure" chemical design in which charge-neutral and charged monolayer-building blocks with highly disparate chemical and physical properties are conjugated vertically through asymmetrically charged interfaces. We demonstrate vdW-ES heteroassembly of semiconducting MoS2 and dielectric Ca2Nb3O10- (CNO) monolayers using an amphipathic molecular starch, resulting in the emergence of trion luminescence observed at the lowest energy among MoS2-related materials, probably due to interfacial confinement effects given by vdW-ES dual interactions. In addition, interface engineering leads to tailored exciton of the vdW/ES heterostructures owing to the pronounced dielectric proximity effects, bringing an intriguing interlayer chemistry to modify 2D materials. Furthermore, the current approach was successfully extended to create a graphene/CNO heterostructure, which verifies the versatility of the preparative method.

Carbon nanotube (CNT) incorporated thin film nanocomposite (TFN) is a promising membrane for gas separation. However, agglomeration of CNT tends to occur due to its high aspect ratio and strong Van de Waals force. This study aims to improve the dispersion of CNT in TFN membrane through the addition of amphiphilic graphene oxide (GO) nanosheet. Interfacial polymerization (IP) technique was employed for the synthesis of thin selective layer atop a porous polysulfone (PSF) support. Amino acid functionalization was performed on CNT and GO and its impact on IP was evaluated. It was observed that the nanomaterials properties such as dispersibility, absorptivity and hydrophilicity could affect the reactivity of IP which in turn altered the characteristics of selective layer. Separation results showed that co-incorporation of amino acid modified CNT and GO improved the permeability and selectivity of TFNs by 30% and 60%, respectively. The resulted TFN was also more reproducible and stable under different applied pressures and exposure to air. The outcome of this study suggested that synergetic incorporation of the two geometrically different carbon-based nanomaterial could provide an additional degree of freedom to control the selective film formation as compared to single-filler incorporation.

Membrane-based separation is an appealing solution to mitigate CO

Exciton–polariton coupling between transition metal dichalcogenide (TMD) monolayer and plasmonic nanostructures generates additional states that are rich in physics, gaining significant attention in recent years. In exciton–polariton coupling, the understanding of electronic-energy exchange in Rabi splitting is critical. The typical structures that have been adopted to study the coupling are “TMD monolayers embedded in a metallic-nanoparticle-on-mirror (NPoM) system.” However, the exciton orientations are not parallel to the induced dipole direction of the NPoM system, which leads to inefficient coupling. Our proposed one-dimensional plasmonic nanogrooves (NGs) can align the MoS2 monolayers’ exciton orientation and plasmon polaritons in parallel, which addresses the aforementioned issue. In addition, we clearly reveal the maximum surface potential (SP) change on intermediate coupled sample by the photo-excitation caused by the carrier rearrangement. As a result, a significant Rabi splitting (65 meV) at room temperature is demonstrated. Furthermore, we attribute the photoluminescence enhancement to the parallel exciton–polariton interactions.

Two‐dimensional (2D) transition metal dichalcogenides (TMDCs) with unique electrical properties are fascinating materials used for future electronics. However, the strong Fermi level pinning effect at the interface of TMDCs and metal electrodes always leads to high contact resistance, which seriously hinders their application in 2D electronics. One effective way to overcome this is to use metallic TMDCs or transferred metal electrodes as van der Waals (vdW) contacts. Alternatively, using highly conductive doped TMDCs will have a profound impact on the contact engineering of 2D electronics. Here, a novel chemical vapor deposition (CVD) using mixed molten salts is established for vapor–liquid–solid growth of high‐quality rhenium (Re) and vanadium (V) doped TMDC monolayers with high controllability and reproducibility. A tunable semiconductor to metal transition is observed in the Re‐ and V‐doped TMDCs. Electrical conductivity increases up to a factor of 108 in the degenerate V‐doped WS2 and WSe2. Using V‐doped WSe2 as vdW contact, the on‐state current and on/off ratio of WSe2‐based field‐effect transistors have been substantially improved (from ≈10–8 to 10–5 A; ≈104 to 108), compared to metal contacts. Future studies on lateral contacts and interconnects using doped TMDCs will pave the way for 2D integrated circuits and flexible electronics., A chemical vapor deposition method using mixed molten salts is established for vapor–liquid–solid growth of Re‐ and V‐doped transition metal dichalcogenide (TMDC) monolayers. Tunable semiconductor to metal transition is observed in the as‐grown Re‐ and V‐doped TMDC monolayers. Using heavily V‐doped WSe2 as van der Waals contact, the performance of WSe2‐based field‐effect transistors is improved by 1–3 orders of magnitude compared to Au and Pd.

Two-dimensional (2D) nanomaterials constitute one of the most advanced research targets in materials science and engineering in this century. Among various methods for the synthesis of 2D nanomaterials, including top-down exfoliation and bottom-up crystal growth, chemical exfoliation has been widely used to yield monolayers of various layered compounds, such as clay minerals, transition metal chalcogenides (TMDCs), and oxides, long before the discovery of graphene. Soft chemical exfoliation is a technique to weaken the layer-to-layer interaction in layered compounds by chemical modification of interlayer galleries, which promotes monolayer exfoliation. The chemical exfoliation process using organic substances, typically amines, has been applied to a range of layered metal oxides and hydroxides for two decades, establishing high-yield exfoliation into their highly crystalline monolayers and colloidal integration processes have been developed to assemble the resultant 2D nanomaterials into well-organized nanoscale devices. Recently, such a strategy was found to be effective for TMDC and MXene nanosheets, expanding the lineup of functionalities of solution-processed 2D nanomaterial devices from dielectrics, optics, magnetics, and semiconductors to superconductors. Throughout this review, we share the historical research flow, recent progress, and prospects in the development of soft-chemical exfoliation, colloidal integration, and thin film applications of oxides, TMDC, and MXene nanosheets.

The usage of molten salts, e.g., Na2MoO4 and Na2WO4, has shown great success in the growth of two-dimensional (2D) transition metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). In comparison with the halide salt (i.e., NaCl, NaBr, KI)-assisted growth (Salt 1.0), the molten salt-assisted vapor-liquid-solid (VLS) growth technique (Salt 2.0) has improved the reproducibility, efficiency and scalability of synthesizing 2D TMDCs. However, the growth of large-area MoSe2 and WTe2 is still quite challenging with the use Salt 2.0 technique. In this study, a renewed Salt 2.0 technique using mixed salts (e.g., Na2MoO4-Na2SeO3 and Na2WO4-Na2TeO3) is developed for the enhanced CVD growth of 2D MoSe2 and WTe2 crystals with large grain size and yield. Continuous monolayer MoSe2 film with grain size of 100-250 {\mu}m or isolated flakes up to ~ 450 {\mu}m is grown on a halved 2-inch SiO2/Si wafer. Our study further confirms the synergistic effect of Na+ and SeO32- in the enhanced CVD growth of wafer-scale monolayer MoSe2 film. And thus, the addition of Na2SeO3 and Na2TeO3 into the transition metal salts could be a general strategy for the enhanced CVD growth of many other 2D selenides and tellurides., Comment: 35 pages, 11 figures and 1 table

Two-dimensional transition metal dichalcogenides (TMDCs) have studied intensively owing to their unique optical and electronic properties [1]. Among TMDCs, monolayer molybdenum disulfide (MoS2) is a direct bandgap semiconductor with strong binding energies which make it as a perfect candidate for light-matter coupling system. In the current work, we fabricated hybrid systems of MoS2 monolayers [2] and 1D plasmonic nanogrooves made of gold (Au) to study exciton-plasmon coupling, particularly the carrier transport at the coupling state (see Fig. 1(a)). The nanogrooves were suited to excite in-plane plasmons, which are different from metallic-nanoparticle-on-mirror configuration.(/p)(p)The exciton-plasmon couplings were confirmed by the reflectance measurements and the dispersion relations were plotted from the reflectance measurements as shown in Fig. 1(b). In Fig. 1(b), the plasmon-exciton coupling of the upper polariton and lower polariton were plotted as a function of detuning. The splitting energy was as large as 65 meV, which is one of the largest among the values reported so far at room temperature. The exciton-plasmon coupling has also been confirmed by the Kelvin probe force microscope (KPFM) which recorded the surface potentials. As shown in Fig. 1(c), while there was no surface potential change for the MoS2 on planar Au film, a surface potential shift of 13.5 meV was observed for the MoS2 on nanogroove upon laser irradiation at 532 nm. This is a direct evidence that surface potential shift was induced at the exciton-plasmon coupling. Our results indicated that the 1D plasmonic nanogrooves are appropriate structures to study exciton-plasmon coupling with large splitting energy at room temperature.

Efficient electrocatalysts are highly demanded for oxygen evolution reaction (OER) in water splitting and metal-air batteries. Here, superlattice structured materials composed of CoNiFe layered double hydroxide (LDH)/ruthenium oxide nanosheets are synthesized as carbon-free electrocatalysts for OER. The positively charged CoNiFe LDH and negatively charged RuO

Molecularly thin two-dimensional (2D) semiconductors are emerging as photocatalysts owing to their layer-number-dependent quantum effects and high charge separation efficiency. However, the correlation among the dimensionality, crystallinity, and photocatalytic activity of such 2D nanomaterials remains unclear. Herein, a Ag photoreduction technique coupled with microscopic analyses is employed to spatially resolve the photocatalytic activity of MoS

Owing to its cost-effectiveness and low-energy consumption, solution-processing of functional metal oxide films has been extensively studied over the past few decades. However, direct-solution routes to crystalline hematite (α-Fe2O3) films without post-heat treatment have not been explored yet. This is because the solution-processing of these films involves the preferential formation of other iron oxides, hydroxides, and oxyhydroxides during the conventional precipitation reactions. Herein, we developed a direct-growth route for the preparation of crystalline α-Fe2O3 using the spin spray (SPS) technique. We carried out the liquid phase-atomic layer deposition (LP-ALD) of α-Fe2O3. The mechanism involved the surface adsorption of Fe2+ followed by the oxidization and formation of Fe3+–O2− bonds. The LP-ALD approach facilitated the low-temperature direct growth of highly crystalline, dense, and uniform α-Fe2O3 films at 95 °C with a high deposition rate of 6.3 nm min−1. The deposition temperature and rate are much lower and higher than those offered by cutting edge gas-phase ALD techniques (230 °C and 1.3 × 10−2 nm min−1), respectively. Furthermore, the effects of the growth conditions on the formation and microstructure of the products were investigated in detail in order to elucidate the LP-ALD mechanism.

A fluorescent dye-labeled DNA probe was adsorbed and quenched on the monolayer of RuO

Both p- and n-type field effect transistors (FET) properties have been observed in undoped reduced graphene oxide (rGO). Short and long time exposure of GO during photo reduction results in the formation of respective p- and n-type rGO semiconductor. Achieving duel behavior of this type in an undoped material is exceedingly unusual. Herein we report the presence of such behavior in the reduced from of graphene oxide (rGO) for the first time.

A Rabi splitting of 90 meV at room temperature is estimated from monolayer M0S2 coupled to plasmonic gold nanogrooves which was confirmed by the photoluminescent enhancement, Kelvin probe force microscope scanning, and fluorescence lifetime measurement

Vapor transportation is the core process in growing transition-metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). One inevitable problem is the spatial inhomogeneity of vapors. The non-stoichiometric supply of transition-metal precursors and chalcogens leads to poor control in the products' location, morphology, crystallinity, uniformity and batch to batch reproducibility. The vapor-liquid-solid (VLS) growth method often involves molten precursors (e.g., non-volatile Na2MoO4) at growth temperatures higher than their melting points. The liquid Na2MoO4 can precipitate out solid MoS2 monolayers when saturated with sulfur vapor. Taking advantage of the VLS growth, we attained three kinds of important achievements: (i) a 4-inch-wafer-scale uniform growth of MoS2 flakes on SiO2/Si substrates, (ii) a 2-inch-wafer-scale growth of continuous MoS2 film with the grain size exceeding 100 μm on sapphire substrates, and (iii) a patterned (site-controlled) growth of MoS2 flakes and films. We clarified that the VLS growth thus paves a new way for the high-efficient and scalable synthesis of two-dimensional TMDC monolayers.

A 1.3 nm-thick nickel hydroxide (p-type, 0.5 nm)/titania (n-type, 0.8 nm) pn junction prepared by lamination of nanosheets improved the onset potential for photoelectrochemical oxidation and increased the photooxidation current, indicating that ultrathin pn junctions suppress the recombination of photo-generated carriers.

A new strategy using mixed salts for chemical vapor deposition of tunable Re‐ and V‐doped 2D transition metal dichalcogenides (TMDCs) is realized by Shisheng Li, Takaaki Taniguchi, and co‐workers, as described in article number 2004438. By applying the highly conductive V‐doped WSe(2) as van der Waals contacts for 2D WSe(2) based field‐effect transistor, the on‐state current and on/off ratio are substantially improved, compared to the metal contacts. [Image: see text]

Vapor transportation is the core process in growing transition-metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). One inevitable problem is the spatial inhomogeneity of the vapors. The non-stoichiometric supply of transition-metal precursors and chalcogen leads to poor control in products' location, morphology, crystallinity, uniformity and batch to batch reproducibility. While vapor-liquid-solid (VLS) growth involves molten precursors at the growth temperatures higher than their melting points. The liquid sodium molybdate can precipitate solid MoS2 monolayers when saturated with sulfur vapor. Taking advantage of the VLS growth, we achieved three kinds of important achievements: (a) 4-inch-wafer-scale uniform growth of MoS2 flakes on SiO2/Si substrates, (b) 2-inch-wafer-scale growth of continuous MoS2 film with a grain size exceeding 100 um on sapphire substrates, and (c) pattern (site-controlled) growth of MoS2 flakes and film. We clarified that the VLS growth thus pave the new way for the high-efficient, scalable synthesis of two-dimensional TMDC monolayers., Comment: 30 pages, 10 figures

International audience; Long poly-diacetylene chains are excellent candidates for planar, on-surface synthesizedmolecular electronic wires. Since hexagonal-Boron Nitride (h-BN) was identified as the bestavailable atomically flat insulator for the deposition of poly-diacetylene precursors, we demonstratethe polymerization patterns and rate on it under UV-light irradiation, with subsequent polymeridentification by atomic force microscopy. The results on h-BN indicate self-sensitization whichyields blocks comprised of several polymers, unlike on the well-studied graphite/diacetylene system,where the polymers are always isolated. In addition, the photo-polymerization proceeds at least170 times faster on h-BN, where it also results in longer polymers. Both effects are explained bythe h-BN bandgap, which is larger than the diacetylene electronic excitation energy, thus allowingthe transfer of excess energy absorbed by polymerized wires to adjacent monomers, triggeringtheir polymerization. This work sets the stage for conductance measurements of single molecularpoly-diacetylene wires on h-BN.

We have developed a new synthesis method that includes a chemical vapor deposition process in a chamber settled in organic liquid, and applied its nonequilibrium reaction field to the development of novel carbon nanomaterials. In the synthesis at 1110–1120 K, using graphene oxide as a catalyst support, iron acetate and cobalt acetate as catalyst precursors, and 2-propanol as a carbon source as well as the organic liquid, we succeeded to create carbon nanofiber composed of novel pot-shaped units, named carbon nanopot. A carbon nanopot has a complex and regular nanostructure consisting of several parts made of different layer numbers of graphene and a deep hollow space. Dense graphene edges, hydroxylated presumably, are localized around its closed end. The typical size of a carbon nanopot was 20–40 nm in outer diameter, 5–30 nm in inner diameter, and 100–200 nm in length. A growth model of carbon nanopot and its applications are proposed.

Ceria nanoparticles with controlled crystal orientations were fabricated via an oleate-modified hydrothermal method, which involved varying the molar ratio of oleate ions to cerium ions in the reaction solution ([Ole/Ce]) from 0 to 1. Quasicubic nanoparticles having primary {1 0 0} facets in addition to {1 1 0} edges were obtained for [Ole/Ce] values greater than 1/2. On the other hand, polyhedral nanoparticles surrounded by primary {1 1 1} facets appeared on nanoparticle surface at [Ole/Ce] smaller than 1/4. It was found that the bonding of the carboxyl terminals of the oleate ions with the cerium(IV) ions on the {1 0 0} surfaces balanced the electric charge of the stacked layers and that this is what resulted in the formation of cubic nanoparticles surrounded by {1 0 0} facets for [Ole/Ce] values larger than 1/2.

Oxygen functional groups (OFGs) in graphene oxide (GO) are responsible for the unique optical, electrical, magnetic as well as ionic, liquid and gaseous transport properties. In the present study, we have discovered reversible epoxide opening/closing reactions in GO upon alkaline and acid treatments, respectively, under ambient conditions. We suggest that unique properties of GO including stability of the carbocation and fast proton migration on the surfaces enable the unusual pH-driven epoxide ring opening/closing reactions. Our experimental results indicate that an irreversible epoxy formation observed in base-treated GO under flux conditions is due to the decomposition of the vic-diol groups formed by epoxy ring opening in alkaline solutions. A high concentration of basal plane epoxides is a remarkable feature of GO. Thus, the reversible epoxy formation should be an important part of our understanding of reactivity and properties of GO. For example, the epoxy ring opening can be a mechanism for anomalous photoluminescent (PL) quenching of GO dispersions in alkaline conditions.

In this research, we developed the device that makes it possible to present a haptic sense in a wide range of a hand with high-density. This device is composed of a plurality of modules with built-in pin arrays and pneumatically drives the pins in the module compress the skin and present the haptic sense. There is 2 type of devices, one’s density of pins evenly distributed on the whole hand (device1), and the other’s density of pins are arranged with high-density of fingertips based on a 2-point threshold (device2). The total number of pins was 128 for both devices. The Controller of the device was composed of electro-pneumatic regulators, a control circuit, and a PC. Force presented by each actuator was computed based on the simulation of contact between the virtual hand and object. In order to evaluate the performance of these devices, 3-dimensional shape recognition experiment of virtual objects was conducted. Measurement results of correct answer rate and response time were 65.6% and 46.1 s in device1. The results of device2 were 70.3% and 40.2 s. From these results, it was suggested that the arrangement of the presentation stimuli based on the 2-point discrimination threshold is effective for the tactile recognition.

Chemical vapor deposition (CVD) of two-dimensional (2D) materials such as monolayer MoS2 typically involves the conversion of vapor-phase precursors to a solid product in a process that may be described as a vapor-solid-solid (VSS) mode. Here, we report the first demonstration of vapor-liquid-solid (VLS) growth of monolayer MoS2 yielding highly crystalline ribbon-shaped structures with a width of a few tens of nanometers to a few micrometers. The VLS growth mode is triggered by the reaction between molybdenum oxide and sodium chloride, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the "crawling mode" when saturated with sulfur on a crystalline substrate. Our growth yields straight and kinked ribbons with a locally well-defined orientation, reflecting the regular horizontal motion of the liquid droplets during growth. Using atomic-resolution scanning transmission electron microscopy (STEM) and second harmonic generation (SHG) microscopy, we show that the ribbons are homoepitaxially on monolayer MoS2 surface with predominantly 2H- or 3R-type stacking. These findings pave the way to novel devices with structures of mixed dimensionalities., Comment: 40 pages, 19 figures

We successfully developed an efficient proton/electron mixed conductor composed of a single phase material that functions at room temperature by introducing sulfate ions into graphene oxide interlayers. The promising properties of this material would allow for its wide use in fuel cells, supercapacitors, and gas separation membranes.

Modification of tRNA anticodons plays a critical role in ensuring accurate translation. N4-acetylcytidine (ac4C) is present at the anticodon first position (position 34) of bacterial elongator tRNAMet. Herein, we identified Bacillus subtilis ylbM (renamed tmcAL) as a novel gene responsible for ac4C34 formation. Unlike general acetyltransferases that use acetyl-CoA, TmcAL activates an acetate ion to form acetyladenylate and then catalyzes ac4C34 formation through a mechanism similar to tRNA aminoacylation. The crystal structure of TmcAL with an ATP analog reveals the molecular basis of ac4C34 formation. The ΔtmcAL strain displayed a cold-sensitive phenotype and a strong genetic interaction with tilS that encodes the enzyme responsible for synthesizing lysidine (L) at position 34 of tRNAIle to facilitate AUA decoding. Mistranslation of the AUA codon as Met in the ΔtmcAL strain upon tilS repression suggests that ac4C34 modification of tRNAMet and L34 modification of tRNAIle act cooperatively to prevent misdecoding of the AUA codon.

The rapid development of flexible and wearable electronics has led to an increase in the demand for flexible supercapacitors with enhanced electrochemical performance. Graphene oxide (GO) and reduced GO (rGO) exhibit several key properties required for supercapacitor components. Although solid-state rGO/GO/rGO supercapacitors with unique structures are promising, their moderate capacitance is inadequate for practical applications. Herein, we report a flexible solid-state rGO/GO/rGO supercapacitor comprising H2SO4-intercalated GO electrolyte/separator and pseudocapacitive rGO electrodes, which demonstrate excellent electrochemical performance. The resulting supercapacitor delivered an areal capacitance of 14.5 mF cm–2, which is among the highest values achieved for any rGO/GO/rGO supercapacitor. High ionic concentration and fast ion conduction in the H2SO4-intercalated GO electrolyte/separator and abundant CH defects, which serve as pseudocapacitive sites on the rGO electrode, were responsible for the high...

Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour-solid-solid mode. Here, we report the vapour-liquid-solid growth of monolayer MoS

Optical and magnetic properties of graphene oxide (GO) have been intensively investigated because of the promising applications of GO-related materials in various technical fields. So far, the optical and magnetic properties of GO have been discussed independently. However, localized electronic states in reduced GO may simultaneously add optical transitions and spin moments in sp2 nanodomains in GO nanosheets. In the present study, the structural, optical, and magnetic properties of graphene oxide (GO) photoreduced in an aqueous solution are correlated on the basis of experimental and theoretical investigations. Experimental observations show that photoreduction leads to enhancement of visible absorption, quenching of photoluminescence, and emergence of magnetism. Detailed spectroscopic and microscopic characterizations indicate the presence of photoreduction-produced basal plane C—H bonding and carbon vacancies. Ab initio calculations suggest that the presence of these defects in sp2 nanodomains results ...

Graphene oxide (GO) and reduced graphene oxide exhibit proton and electron (or hole) conduction, respectively. Owing to this, the conductivity of GO can be controlled via reduction because its electron conductivity increases and its proton conductivity depends on the concentration of epoxide groups. Herein, we report the successful control of the proton and electron conductivities of GO using the photoirradiation and thermal reduction processes. The proton conductivity decreases when the epoxide content and layer distance decreases, whereas the electron conductivity drastically increases with decreasing oxygen content. Both the electron and proton conduction mechanisms for GO are discussed based on the concentrations of various functional groups and defects, changes in the interlayer distance, and the activation energy associated with proton conduction. Finally, we determined the most suitable degree of reduction for obtaining a good mixed conductor useful as an electrode material and a hydrogen separatio...