Search

Herein, we introduced surface modification of a Cu catalyst by employing CH4 pre-annealing, which changed the uniformly rough Cu surface; this resulted in formation of high-quality and uniform Bern...

To improve the reversible capacity and electrochemical performance of the Li-ion batteries, prelithiation is one of the promising solutions as it leads to the reduction of irreversible capacity and stabilization of electrode surfaces after prelithiation. However, typical electrochemical prelithiation has drawbacks including a longer reaction period and low efficiency of the process. Here, we demonstrate a facile route for the one-pot synthesis of chemically prelithiated graphene before assembling the battery cell. In the reaction of a mixture consisting of graphene oxide (GO), lithium, and 4,4′-di-tert-butylbiphenyl (DTBP), the prelithiation and reduction of GO have occurred simultaneously by the assistance of DTBP. The prelithiated graphene exhibits improved reversible capacity (643 mAh g–1), cyclic stability (capacity retention of 87.4% after 200th cycle), and rate capability compared to those of GO and reduced graphene oxide (RGO). This chemical prelithiation method is expected to enable the efficient production of prelithiated graphene anodes for improving the performance of Li-ion batteries.

Reliable and controllable doping of transition metal dichalcogenides (TMDCs) is a mandatory requirement for practical large-scale electronic applications. However, most of the literature on the doping methodologies of TMDCs has focused on n-type doping and multilayer TMDC rather than a monolayer one enabling large-scale growth. Herein, we report substitutional fluorine doping of a chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS2) monolayer film using a delicate SF6 plasma treatment. Our SF6-treated MoS2 monolayer shows a p-type doping effect with fluorine substitution. The doping concentration is controlled by the plasma treatment time (2-4.9 atom %) while maintaining the structural integrity of the MoS2 monolayer. Such reliable and tunable substitutional doping is attributed to preventing direct ion bombardment to the MoS2 monolayer by our gentle plasma treatment system. Finally, we fabricated MoS2 homojunction flexible inverter device arrays based on the pristine and SF6-treated MoS2 monolayer. A clear switching behavior is observed, and the voltage gain is approximately 8 at an applied VDD of 2 V, which is comparable to that of CVD-grown MoS2-based inverter devices reported previously. Obtained voltage gain is also stable even after 500 bending cycles at an applied strain of 0.5%.

Controlling aspect ratio of copper (Cu) nanowire (NW) is a vital role to determine the conductivity at a high transmittance for the transparent conductive electrode application, but systemic studies on aspect ratio control of Cu NW have been still in early stages. Herein, we systemically explore the aspect ratio of Cu NW by varying solution process parameters including reaction time and the concentration of additives (Cu precursor, reducing agent, and capping agent). From optimized process parameters, we successfully synthesize Cu NWs showing the high aspect ratio of ~ 1570, which is relatively comparable than that of previous reports. We characterize the sheet resistance with different transmittances, and consequently achieve excellent sheet resistance of 46 Ω sq−1 at transmittance = 93%, similar to that of indium tin oxide-based electrodes. Obtained Cu NW films also show stable bending reliability with applying bending radius of 6.5 mm. Such remarkable performances are attributed to high aspect ratio of our Cu NWs, which lead to reduced junction resistance in films.

Two-dimensional (2D) molybdenum disulfide (MoS2) is the most mature material in 2D material fields owing to its relatively high mobility and scalability. Such noticeable properties enable it to realize practical electronic and optoelectronic applications. However, contact engineering for large-area MoS2 films has not yet been established, although contact property is directly associated to the device performance. Herein, we introduce graphene-interlayered Ti contacts (graphene/Ti) into large-area MoS2 device arrays using a wet-transfer method. We achieve MoS2 devices with superior electrical and photoelectrical properties using graphene/Ti contacts, with a field-effect mobility of 18.3 cm2/V∙s, on/off current ratio of 3 × 107, responsivity of 850 A/W, and detectivity of 2 × 1012 Jones. This outstanding performance is attributable to a reduction in the Schottky barrier height of the resultant devices, which arises from the decreased work function of graphene induced by the charge transfer from Ti. Our research offers a direction toward large-scale electronic and optoelectronic applications based on 2D materials.

Refractory high-entropy alloys (RHEAs) have opened a new chapter in the development of structural materials for use at high temperatures owing to their outstanding mechanical properties and thermal stability. In this study, we developed a NbMoTaW RHEA thin film via direct current magnetron sputtering from a single target that was synthesized by sintering a mixture of multiple elemental powders. The as-deposited thin film exhibited a single nanocrystalline solid-solution phase with body-centered cubic structure. Moreover, the film had a high hardness of 12 GPa and electrical resistivity of 168 μΩ·cm due to severe lattice distortion and the presence of nanoscale grains. Hence, RHEA films can be used as a hard coating for protective layers and as electrical resistors in nanofabricated devices owing to their favorable combination of hardness and electrical resistivity.

To meet the overwhelming demands of next-generation energy storage devices, efforts to develop advanced electrode materials with excellent specific capacity/capacitance and cyclic durability are underway. In this study, we develop hierarchical ternary composites based on Au@TiO2 core-shell nanoparticles anchored onto reduced graphene oxide nanosheets through a one-pot hydrothermal method. These composites can be utilized as anodes for electrochemical lithium storage. The ternary composite anodes deliver a high specific capacity of 905 mAh g−1 at 100 mA g−1 after 100 cycles, accompanied by good rate capability. Hybrid lithium-ion capacitors with Au@TiO2/reduced graphene oxide anodes and activated carbon cathodes show a maximum energy density of 110 Wh kg−1 and power density of 11 kW kg−1, along with excellent capacitance retention of 83%, even after 1000 cycles. This suggests that our composites have potential as electrode materials for high-performance supercapacitors.

Current lithium-ion batteries have a low theoretical capacity that is insufficient for use in emerging electric vehicles and energy-storage systems. The development of lithium-sulfur batteries utilizing Li2 S cathodes would be a promising option to overcome the capacity limitation. In this work, new three-dimensional (3D) honeycomb-like N-doped carbon nanowebs (HCNs) have been synthesized through a facile aqueous solution route for use as a cathode material in lithium-sulfur batteries. The Li2 S@HCNs cathode delivers a high discharge capacity of approximately 815 mAh g-1 after 65 cycles at 0.1 C, along with a superior rate capacity of approximately 568 mAh g-1 even at 2 C. The outstanding electrochemical rate performance is ascribed to their unique 3D honeycomb-like nanoweb structure, consisting of nanowires derived from polypyrrole. These properties greatly enhance the electrochemical reaction kinetics by providing efficient electron pathways and hollow channels for electrolyte transport. Nitrogen doping in the carbon nanowebs also considerably improves the chemisorption properties by tuning affinity between sulfur and oxygen functional groups on the carbon framework. The simple synthesis strategy and the resulting unique electrode structure could present a new avenue in nanostructure research for high-performance lithium-sulfur batteries.

In this paper, an anode material system of Co3O4 nanowires composited with reduced graphene oxide (Co3O4 NWs/rGO) and protected by N-doped carbon layer (Co3O4 NWs/rGO@NC) was prepared for lithium ion batteries. The N-doped carbon layer could serve as stress relief matter to reduce volume changes of the Co3O4 NWs/rGO during repeated charge/discharge cycles, and also enhance the reaction kinetics as a highly conductive layer between the Co3O4 NWs and electrolyte. The Co3O4 NWs/rGO@NC electrode delivered a high discharge capacity of ca. 995 mAh g−1 at 0.1 C after 65 cycles, and showed a much better rate performance of 428 mAh g−1 even at a high current rate of 5 C as compared to those of Co3O4 NWs/rGO electrode (203 mAh g−1). The demonstrated electrochemical properties suggested that the N-doped carbon coating on the composite of Co3O4 NWs and rGO could significantly enhance the durability and rate capability of the anode material for high performance lithium ion batteries.

Here, we demonstrate the fabrication of a Cu-graphene heterostructure interconnect by the direct synthesis of graphene on a Cu interconnect with an enhanced performance. Multilayer graphene films were synthesized on Cu interconnect patterns using a liquid benzene or pyridine source at 400 °C by atmospheric pressure chemical vapor deposition (APCVD). The graphene-capped Cu interconnects showed lower resistivity, higher breakdown current density, and improved reliability compared with those of pure Cu interconnects. In addition, an increase in the carrier density of graphene by doping drastically enhanced the reliability of the graphene-capped interconnect with a mean time to failure of >106 s at 100 °C under a continuous DC stress of 3 MA cm−2. Furthermore, the graphene-capped Cu heterostructure exhibited enhanced electrical properties and reliability even if it was a damascene-patterned structure, which indicates compatibility with practical applications such as next-generation interconnect materials in CMOS back-end-of-line (BEOL).

The graphene quantum dot (GQD) is a carbon allotrope with a planar surface amenable for functionalization and nanoscale dimensions that confer photoluminescent properties. Collectively, these properties render GQDs an advantageous platform for nanobiotechnology applications, including as optical biosensors and delivery platforms. In particular, noncovalent functionalization offers a route to reversible modification and preservation of the pristine GQD substrate. However, a clear paradigm for GQD noncovalent functionalization has yet to be realized. Herein, we demonstrate the feasibility of noncovalent polymer adsorption to the GQD surface, with a specific focus on single-stranded DNA (ssDNA). We study how GQD oxidation level affects the propensity for polymer adsorption by synthesizing and characterizing four types of GQD substrates and investigating noncovalent polymer association to these substrates. Distinct adsorption methods are developed for successful ssDNA attachment based upon the GQD’s initial level of oxidation. ssDNA adsorption to the GQD is confirmed by atomic force microscopy, by inducing ssDNA desorption, and with molecular dynamics simulations. ssDNA is determined to adsorb strongly to no-oxidation GQDs, weakly to low-oxidation GQDs, and not at all for heavily oxidized GQDs. We hypothesize that high GQD oxygen content disrupts the graphitic carbon domains responsible for stacking with the aromatic ssDNA bases, thus preventing the formation of stable polymer-GQD complexes. Finally, we develop a more generic adsorption platform and assess how the GQD system is tunable by modifying both the polymer sequence and type.

A novel polysulfone (PSf) nanocomposite ultrafiltration (UF) membrane using sulfonated graphene oxide (SGO) as additives was fabricated and investigated. SGO nanoparticles were chemically synthesized from graphene oxide (GO) by using sulfuric acid (H2SO4) and were confirmed by Raman and Fourier transform infrared (FTIR) spectroscopy. The morphology of prepared membranes was characterized by scanning electron microscopy (SEM), energy dispersive x-ray (EDX) and atomic force microscopy (AFM). Results showed that adding small amount (less than 0.3 wt%) of SGO improved wettability, porosity and mean pore size of PSf/SGO membranes compared to the pristine PSf membrane and significantly enhanced the water flux of SGO incorporated PSf membranes. In UF performance, the nanocomposite membrane prepared by adding 1.5 w/w% SGO of PSf (designated as M1.5) showed the highest water flux result, which was 125% higher than the control PSf membrane (no SGO addition). Interestingly, there was no trade-off between water flux and bovine serum albumin (BSA) rejection, i.e more than 98% BSA rejection. The addition of SGO hydrophilic additives also showed better results in long-term BSA separation performance. The enhancement of hybrid membrane's properties was attributed to the hydrophilicity of sulfonic acid group ( SO3H) on the surface of SGO additive. This study suggested that the SGO nanoparticle is a promising candidate to modify the PSf UF membranes.

Contact engineering for two-dimensional (2D) transition metal dichalcogenides (TMDCs) is crucial for realizing high-performance 2D TMDC devices, and most studies on contact properties of 2D TMDCs have mainly focused on Fermi level unpinning. Here, we investigated electrical and photoelectrical properties of chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS

Understanding charge transfer processes between graphene and functional materials is crucial from the perspectives of fundamental sciences and potential applications, including electronic devices, photonic devices, and sensors. In this study, we present the charge transfer behavior of graphene and amine-rich polyethyleneimine (PEI) upon CO2 exposure, which was significantly improved after introduction of hygroscopic polyethylene glycol (PEG) in humid air. By blending PEI and PEG, the number of protonated amine groups in PEI was remarkably increased in the presence of water molecules, leading to a strong electron doping effect on graphene. The presence of CO2 gas resulted in a large change in the resistance of PEI/PEG-co-functionalized graphene because of the dramatic reduction of said doping effect, reaching a maximum sensitivity of 32% at 5,000 ppm CO2 and an applied bias of 0.1 V in air with 60% relative humidity at room temperature. This charge transfer correlation will facilitate the development of portable graphene-based sensors for real-time gas detection and the extension of the applications of graphene-based electronic and photonic devices.

The corrosion of metals can be induced by different environmental and operational conditions, and protecting metals from corrosion is a serious concern in many applications. The development of new materials and/or technologies to improve the efficiency of anti-corrosion coatings has attracted renewed interest. In this study, we develop a protective coating composed of a bilayer structure of reduced graphene oxide (RGO)/graphene oxide (GO) applied to Cu plates by spray-coating and subsequent annealing. The annealing of the GO/Cu plates at 120 °C produces a bilayer structure of RGO/GO by the partial reduction of the spray-coated GO layer. This induces superior corrosion resistance and adhesion strength compared to those of GO/Cu and RGO/Cu plates because of the hydrophobic nature of the RGO surface exposed to the surroundings and the formation of Cu–O bonds with the O-based functional groups of GO. This approach provides a viable and scalable route for using graphene coatings to protect metal surfaces from corrosion.

We report the structural and electrical properties of Li-doped ZnO (LZO) films, which are spin-coated via a simple solution process using Zn and Li precursor solutions. The Li doping improves the crystallinity of the ZnO films, and the LZO films exhibit a relatively dense and smooth surface morphology compared to that of the undoped ZnO films. Back-gated LZO thin-film transistors (TFTs) are fabricated onto a heavily p-doped Si substrate with a SiO2 gate dielectric, and operated in enhancement mode. In the case of the LZO TFT with a Li doping concentration of 0.50 mol%, the highest field-effect mobility of 5.18 cm2 V−1 s−1 is obtained; the on/off current ratio and subthreshold swing are 107 and 1.2 V dec−1, respectively. These results demonstrate that Li doping can effectively modulate the structural and electrical properties of ZnO-based films, facilitating the fabrication of LZO TFTs with enhanced performance.

The progress in developing the microelectromechanical system (MEMS) heater-based SnO 2 gas sensors was hindered by the subsequent heat treatment of the tin oxide (SnO 2 ), nevertheless it is required to obtain excellent sensor characteristics. During the sintering process, the MEMS heater and the contact electrodes can be degraded at such a high temperature, which could reduce the sensor response and reliability. In this research, we presented a process of preheating the printed SnO 2 sensing layer on top of a sacrificial bridge-type ZnO layer at such a high temperature, followed by transferring it onto the contact electrodes of sensor device by selective etching of the sacrificial ZnO layer. Therefore, the sensor device was not exposed to the high sintering temperature. The SnO 2 gas sensor fabricated by the transfer process exhibited a rectangular sensing curve behavior with a rapid response of 52 s at 20 ppm ethanol concentration. In addition, reliable and repeatable sensing characteristics were obtained even at an ethanol gas concentration of 5 ppm.

Membrane-based water reuse and desalination technologies have been increasingly popular as an alternative water resource for mitigating global water scarcity. However, intrinsic limitations of conventional membranes restrict a further advance in membrane-based technologies. Recently, laminar-structure graphene oxide (GO) membranes fabricated by staking GO nanoplatelets have been emerging as a new water purification membrane with overcoming the conventional membrane limitations because of ultra-fast water permeation and precise molecular sieving capability based on ultra-low friction and well-defined nanochannels; to apply laminar GO membranes for ion removal such as desalination, tuning size of GO nanochannels within a sub-nanometer range is required. Herein, we adjusted reduction degree of GO laminates via varying exposure time to hydroiodic acid steam to control the size of GO nanochannels in a sub-nanometer range. Control of the hydroiodic acid vapor exposure time is a facile way to tune the nanochannel size in a sub-nanometer, and consequentially monovalent ion rejection rate can be handled.

Understanding the mutual interaction between electronic excitations and lattice vibrations is key for understanding electronic transport and optoelectronic phenomena. Dynamic manipulation of such interaction is elusive because it requires varying the material composition on the atomic level. In turn, recent studies on topological insulators (TIs) have revealed the coexistence of a strong phonon resonance and topologically protected Dirac plasmon, both in the terahertz (THz) frequency range. Here, using these intrinsic characteristics of TIs, we demonstrate a new methodology for controlling electron–phonon interaction by lithographically engineered Dirac surface plasmons in the Bi2Se3 TI. Through a series of time-domain and time-resolved ultrafast THz measurements, we show that, when the Dirac plasmon energy is less than the TI phonon energy, the electron–phonon coupling is trivial, exhibiting phonon broadening associated with Landau damping. In contrast, when the Dirac plasmon energy exceeds that of the p...

There has been a significant interest in the development of novel anode materials that can solve the problems of lithium plating and dendrite formation during the discharge-charge process, thus ensuring safety in Li-ion batteries. We synthesized tetragonal CeVO4 as an alternative to graphite, the active material in commercial Li-ion batteries, via a hydrothermal reaction; CeVO4 has lower lithium insertion potentials of 1.0 and 1.5 V versus Li+/Li compared to those of lithium titanium oxide. In order to overcome the drawbacks of the metal oxide, such as low electrical conductivity and volume change upon cycling, CeVO4/RGO composites were synthesized by mixing CeVO4 uniformly with reduced graphene oxide (RGO) via a solid-state reaction. The CeVO4/RGO composites exhibited improved cycling performance and rate capability, with relatively low charging potential of 1.35 V and high power density of 235 W g−1 at 10 wt% RGO, as compared to the pure CeVO4. Our results suggest that the CeVO4/RGO composites have great potential for use as an anode in lithium ion batteries with high power density and excellent safety.

Graphene is currently one of the most advanced materials under study for the development of a wide range of future device applications, owing to fascinating properties such as high carrier mobility, high electrical conductivity, as well as excellent mechanical flexibility and strength. A key requirement for the practical applications of graphene is the synthesis of large-area, high-quality films at low temperature, especially below 400 °C, which would enable the direct integration of graphene into the manufacturing technologies of complementary metal-oxide semiconductor (CMOS) or flexible devices. Chemical vapor deposition (CVD), a well-known and controllable method to prepare thin films, has attracted significant attention for the synthesis of large-area, uniform graphene samples. Nonetheless, significant efforts are still needed to improve our fundamental understanding of the graphene growth mechanism; a better understanding would enable reducing the growth temperature and optimizing the engineering parameters for the fabrication of new electronic devices. This article reviews recent progress in the low-temperature synthesis of graphene by CVD, with a special focus on the key technical factors that can be controlled to drastically reduce the synthesis temperature. Furthermore, the applications of graphene grown by low-temperature CVD are discussed.

A graphitic capping layer was successfully formed on top of Cu interconnects at room temperature, using a pulsed KrF laser. The change in temperature of the Cu line was maintained below 380 °C during laser irradiation with a fluence of 312.5 mJ/cm2. The resistance and critical current density of graphitic layer-capped Cu interconnects were improved by 2.8% and 5.2%, respectively. The lifetime of graphitic layer-capped Cu interconnects under a constant current stress was improved by 223%.

Forward osmosis (FO) processes have been recognized as a low energy required next-generation desalination technology, but the low performance of polymeric membranes remains a bottleneck in the practical application of FO. Graphene oxide (GO) membranes possess a huge potential as an alternative to polymeric membranes because of their facile fabrication procedure, ultra-thin thickness, controllable pore size, and outperformance of competing materials in terms of water transport rate; the low stability of GO laminates under water and their hydrophobic property (if GO laminates are reduced) remain as problems requiring solution prior to their practical implementation. To solve these problems, herein, the chemical reduction of GO laminates and a hydrophilic adhesive polydopamine (pDA) layer were applied. Reduced GO (rGO) laminates sustainably retained their compacted nanochannels (3.45 A) compared to pristine GO laminates, which increased the selectivity of hydrated ions. In addition, adding a pDA coating onto the rGO laminates improved the hydrophilicity of the rGO laminate surface, which accelerated the water absorption speed. As a result of these synergistic effects, pDA-coated rGO (pDA-rGO) membranes achieved an outstanding water flux of 36.6 L/m2·h, with a reverse solute flux of 0.042 mol/m2·h and a high salt rejection rate of 92.0% in FO.

Broadband detection of mid-infrared (IR) photons extends to advanced optoelectronic applications such as imaging, sensing, and telecommunications. While graphene offers an attractive platform for broadband visible/IR photodetection, previous efforts to improve its responsivity, for example, by integrating light-absorbing colloids or waveguide or antenna fabrication, were achieved at the cost of reduced photon detection bandwidth. In this work, we demonstrate room-temperature operation of a novel mid-IR photodetector based on a graphene–Bi2Se3 heterostructure showing broadband detection and high responsivity (1.97 and 8.18 A/W at mid- and near-IR, respectively), in which simultaneous improvement of the spectral range and responsivity is achieved via exploiting broadband absorption of mid-IR and IR photons in a small-band-gap Bi2Se3 topological insulator and efficient hot carrier separation and strong photogating across the Bi2Se3/graphene interface. With sufficient room for further improvement by interface...

To improve the electrochemical performance of Co 3 O 4 /graphene composites towards high-performance lithium ion batteries, various facile chemical methods have been developed to form hybrid Co 3 O 4 /graphene composites, but the compositions of these composites were considerably different. In this study, a two-step solvothermal synthesis method was employed to accurately control the concentration of Co 3 O 4 nanoparticles (NPs) with particle sizes less than 10 nm in the composite. The Co 3 O 4 /reduced graphene oxide (RGO) composites exhibited the highest reversible capacity of 1600 mAh g −1 at 43 wt% Co 3 O 4 NPs. The synergic effects of the sub-10-nm sized Co 3 O 4 and the RGO sheets resulted in improved reversible capacity, cycling stability, and rate capability, which are caused by a large number of active sites and the short diffusion pathways provided by the nano-sized Co 3 O 4 , as well as the elastic buffer space and conductive pathway provided by the RGO sheets.

Nitrogen-doped graphene was synthesized by hydrothermal treatment of graphene oxide with ammonia at different doping temperatures. As the doping temperature increased, each type of nitrogen-bonding showed different tendencies. There was a high proportion of pyrrolic-N, but the proportion was relatively lower with temperature. Despite its smaller content, pyridinic-N plays a prominent part.

Chemical doping of transition metal dichalcogenides (TMDCs) has drawn significant interest because of its applicability to the modification of electrical and optical properties of TMDCs. This is of fundamental and technological importance for high-efficiency electronic and optoelectronic devices. Here, we present a simple and facile route to reversible and controllable modulation of the electrical and optical properties of WS2 and MoS2via hydrazine doping and sulfur annealing. Hydrazine treatment of WS2 improves the field-effect mobilities, on/off current ratios, and photoresponsivities of the devices. This is due to the surface charge transfer doping of WS2 and the sulfur vacancies formed by its reduction, which result in an n-type doping effect. The changes in the electrical and optical properties are fully recovered when the WS2 is annealed in an atmosphere of sulfur. This method for reversible modulation can be applied to other transition metal disulfides including MoS2, which may enable the fabrication of two-dimensional electronic and optoelectronic devices with tunable properties and improved performance.

The modulation of the electrical properties of graphene and its device configurations for low-power consumption are important in developing graphene-based logic electronics. Here, we demonstrate the change in the charge transport in graphene from ambipolar to unipolar using surface charge transfer doping of the polymer electrolyte. Unipolar graphene field-effect transistors (GFETs) were obtained by the surface treatment of poly(acrylic acid) (PAA) for p-type and poly(ethyleneimine) (PEI) for n-type as polymer-electrolyte gates. In addition, lithium perchlorate (LiClO4) in a polymer matrix can be used for the low-gate voltage operation of GFETs (less than ±3 V) because of its high gating efficiency. Using polymer-electrolyte-gated GFETs, complementary graphene inverters were fabricated with a voltage swing of 57% and maximum voltage gain (Vgain) of 1.1 at a low supply voltage (VDD = 1 V). This is expected to facilitate the development of graphene-based logic devices with low-cost, low-power, and flexible electronics.

Graphene barristors with two parallel connected n-type and undoped graphene channels are used to build a ternary logic switch. Three distinctly separated out current levels are successfully demonstrated and the experimental device parameters obtained from the graphene barristor based ternary switch are used to model the ternary circuit modules. Well-behaving standard ternary inverter, NMIN, NMAX, and ternary comparator have been obtained, confirming the feasibility of large scale integration of ternary logic devices.

We report a novel Mo‐Ni‐Si‐B metallic glass which can be solidified into fully amorphous state by melt-spinning process, with high crystallization onset temperature of over 1100 K, extremely high Vickers hardness of 27.5 ± 2.2 GPa and relatively low Young's modulus of 364.3 ± 6.6 GPa. The dense cluster-packing model suggests that the addition of boron up to 10 at.% can occupy vacant cluster-interstices of (Mo, Ni)-Si cluster arrays, which results in a more efficiently dense-packed cluster structure, destabilizes the formation of nanocrystalline phases, and systematically increases the glass-forming ability (GFA) in Mo‐Ni‐Si‐B alloys. The GFA parameters that do not directly rely on Tg, such as ΔT* and ε parameter, show greater reliability to evaluate GFA for Mo‐Ni‐Si‐B metallic glass exhibiting no clear Tg. The H/E and H2/(2E) ratios of the newly developed Mo‐Ni‐Si‐B metallic glass, which reflect wear resistance and resilience, exhibit the highest values among various hard ceramic materials as well as metallic glass-forming alloys developed up to now. These advantages of Mo‐Ni‐Si‐B metallic glass can be used more widely to form a high temperature wear-resistant coating layer on various substrates. Furthermore, the same idea might be used to form a metallic glass-nitride nanocomposite coating layer by reactive deposition in N2 ambient, with highly lubricative property and high wear-resistance, especially at high temperature. Keywords: Molybdenum, Metallic glass, Glass-forming ability, H versus E ratio, Wear resistance

The resistive switching behaviour of amorphous ZnO (a-ZnO) sandwiched between Ga-doped ZnO (GZO) transparent conductive oxide and Al electrode is reported. Transparent GZO films were deposited on polymer substrates as bottom electrodes using pulsed DC magnetron sputtering at 100 °C, on which a-ZnO films were deposited by RF magnetron sputtering at room temperature. The layered structure prepared in this manner was semi-transparent to visible light and its current–voltage hysteresis was representative of a bipolar resistive switching behaviour. The observation of such a resistive switching behaviour was attributed to the employment of a-ZnO as a dielectric layer and the use of Al and GZO as electrodes, which enabled the formation of Schottky barrier only at the a-ZnO/GZO interface. The conduction through the dielectric layer during the high resistance state was due to the Schottky emission as deduced from the consideration of band structures and the fitting of the current–voltage relations to the various conduction models. Switching to the low resistance state was attributed to the filament formation due to the migration of oxygen vacancies during the set process. In control experiments where crystalline ZnO was used as the dielectric layer, resistive switching behaviour was not observed.

Owing to their multiple redox couples, titanium–niobium-based oxides are still considered promising candidates for use as anodes for safe, rechargeable lithium ion batteries with high energy and power densities. Titanium–niobium-based oxide electrodes have, however, exhibited relatively poor cycling performance as a result of pulverization. In this study, we report on a simple two-step solid-state reaction route for producing hybrid composites of Ti 2 Nb 10 O 29 (TNO) anchored on reduced graphene oxide (RGO), and the electrochemical performance of the resulting TNO/RGO composites. Solid-state reactions enable both the formation of TNO and the uniform distribution of RGO in the TNO/RGO composites. The TNO/RGO composites exhibited discharge and charge capacities of 261 and 256 mAh g −1 , respectively, with much better cycling performance (182 mAh g −1 after the 50th cycles) and rate capability (165 mAh g −1 at a current density of 500 mA g −1 ) compared to the pure TNO.

In the original publication of the article, the Acknowledgements section was published incorrectly. The correct Acknowledgements section is given in this Correction.

A forward osmosis membrane consisting of graphene oxide (GO) nanosheets cooperatively cross-linked by ethylenediamine (EDA) molecule and poly(acrylic acid) (PAA) polymer chain is proposed. Desirable GO-based nanocomposite membrane must satisfy the conflicting requirements of high water flux and salt rejection simultaneously, which is yet to be achieved. In this study, the GO/EDA/PAA nanocomposite structure demonstrates that good water flux (52 LMH) and salt rejection (97%) can be achieved simultaneously by cooperatively employing the short monomer molecule EDA and the long PAA polymer chain within the channel region of the GO nanocomposite membrane structure. It is suggested that the membrane-wide network of hydrogen bonds between the GO nanosheets and the PAA chains aligned parallel to them is supplemented by anchoring carbon-nitrogen covalent bonds between GO and EDA molecules to form the nanocomposite structure. The nanocomposite structure resulting from the configurations of EDA molecules and PAA chains within the channel region provide an optimal condition for blocking hydrated salt ions while allowing the flow of water molecules. Also, it functions as a reinforcement of the membrane structure for the improved structural integrity.

Current lithium-ion batteries have a low theoretical capacity that is insufficient for use in emerging electric vehicles and energy-storage systems. The development of lithium-sulfur batteries utilizing Li

Graphene-oxide (GO) membranes with notable ionic-sieving properties have attracted significant attention for many applications. However, the swelling and unstable nanostructure of GO laminates in water results in enlarged interlayer spacing and a low permeation cut-off, limiting their applicability for water purification and desalination. Herein, we propose novel nitrogen-doped graphene (NG) membranes for use in tunable ion sieving that are made via facile fabrication by a time-dependent N-doping technique. Doping reaction time associated variation in atomic content and bonding configurations strongly contributed to the nanostructure of NG laminates by yielding narrower interlayer spacing and a more-polarized surface than GO. These nanostructural features subsequently allowed ion transport through the combined mechanisms of size exclusion and electrostatic interaction. The stacked NG membranes provided size-dependent permeability for hydrated ions and improved ion selectivity by 1-3 orders of magnitude in comparison to that of a GO membrane. For ions small enough to move through the interlayer spacing, the ion permeation is determined by electrostatic properties of NG membranes with the type of N configuration, especially polarized pyridinic N. Due to these properties, the NG membrane functioned as an unconventionally selective graphene-based membrane with better ion sieving for water purification.

2D transition metal dichalcogenides (TMDCs) have emerged as promising candidates for post-silicon nanoelectronics owing to their unique and outstanding semiconducting properties. However, contact engineering for these materials to create high-performance devices while adapting for large-area fabrication is still in its nascent stages. In this study, graphene/Ag contacts are introduced into MoS

There has been growing interest in developing nanoelectronic devices based on graphene because of its superior electrical properties. In particular, patterning graphene into a nanoribbon can open a bandgap that can be tuned by changing the ribbon width, imparting semiconducting properties. In this study, we report the effect of ribbon width on electrical transport properties of graphene nanoribbons (GNRs). Monolayer graphene sheets and Si nanowires (NWs) were prepared by chemical vapor deposition and a combination of nanosphere lithography and metal-assisted electroless etching from a Si wafer, respectively. Back-gated GNR field-effect transistors were fabricated on a heavily p-doped Si substrate coated with a 300 nm-thick SiO2 layer, by O2 reactive ion etching of graphene sheets using etch masks based on Si NWs aligned on the graphene between the two electrodes by a dielectrophoresis method. This resulted in GNRs with various widths in a highly controllable manner, where the on/off current ratio was inversely proportional to ribbon width. The field-effect mobility decreased with decreasing GNR widths due to carrier scattering at the GNR edges. These results demonstrate the formation of a bandgap in GNRs due to enhanced carrier confinement in the transverse direction and edge effects when the GNR width is reduced.

Understanding the mutual interaction between electronic excitations and lattice vibrations is key for understanding electronic transport and optoelectronic phenomena. Dynamic manipulation of such interaction is elusive because it requires varying the material composition on the atomic level. In turn, recent studies on topological insulators (TIs) have revealed the coexistence of a strong phonon resonance and topologically protected Dirac plasmon, both in the terahertz (THz) frequency range. Here, using these intrinsic characteristics of TIs, we demonstrate a new methodology for controlling electron-phonon interaction by lithographically engineered Dirac surface plasmons in the Bi

We present the photoinduced terahertz responses of topological insulators Bi2Se3. The photoconductance sign is determined by the competition between the topological surface state and the bulk response in n-type, p-type and bulk-insulating Bi 2 Se 3 .