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The objective of this study was to investigate the usefulness of fibrinogen-to-albumin ratio (FAR) as a prognostic marker in patients admitted to an intensive care unit (ICU) compared with Sequential Organ Failure Assessment (SOFA) score, a widely used prognostic scoring system. An inverse probability weighting (IPW) was used to control for selection bias and confounding factors. After IPW adjustment, the high FAR group showed significantly higher risk of 1-year compared with low FAR group (36.4% vs. 12.4%, adjust hazard ratio = 1.72; 95% confidence interval (CI): 1.59–1.86; p < 0.001). In the receiver-operating characteristic curve analysis associated with the prediction of 1-year mortality, there was no significant difference between the area under the curve of FAR on ICU admission (C-statistic: 0.684, 95% CI: 0.673–0.694) and that of SOFA score on ICU admission (C-statistic: 0.679, 95% CI: 0.669–0.688) (p = 0.532). In this study, FAR and SOFA score at ICU admission were associated with 1-year mortality in patients admitted to an ICU. Especially, FAR was easier to obtain in critically ill patients than SOFA score. Therefore, FAR is feasible and might help predict long-term mortality in these patients.

A recent study found that magnetization curves for Y3Fe5O12 (YIG) slab and thick films (>20 μm thick) differed from bulk system curves by their longitudinal spin Seebeck effect in a Pt/YIG bilayer system. The deviation was due to intrinsic YIG surface magnetic anisotropy, which is difficult to adopt extrinsic surface magnetic anisotropy even when in contact with other materials on the YIG surface. This study experimentally demonstrates evidence for extrinsic YIG surface magnetic anisotropy when in contact with a diamagnetic graphene interlayer by observing the spin Seebeck effect, directly proving intrinsic YIG surface magnetic anisotropy interruption. We show the Pt/YIG bilayer system graphene interlayer role using large area single and multilayered graphenes using the longitudinal spin Seebeck effect at room temperature, and address the presence of surface magnetic anisotropy due to magnetic proximity between graphene and YIG layer. These findings suggest a promising route to understand new physics of spin Seebeck effect in spin transport.

Background: To develop the normative data of the Korean version of the MNREAD acuity chart.Methods: A Korean version was prepared based on the MNREAD acuity chart developed by Gordon Legge of the University of Minnesota, USA. A linguist selected the representative 80 sentences composed of 9 words at the level of the 2nd and 3rd grades of elementary school. Reading abilities were measured for 20-35 years old with normal visual acuity (corrected visual acuity of 1.0 or better) for 80 sentences. Among 80 sentences, 38 items with a similar speed were prepared for the right and left eyes of the Korean version according to the format of the MNREAD acuity chart. Reading speed (word per minute, wpm) for healthy participants, the reading acuity (the smallest detectable font size), and the critical print size (the smallest font size without reduction of reading speed) were analyzed.Results: The average age of the experimental group was 28.3 ± 2.6 years (male: female 4=16). The average reading speed for 38 sentences was 3.66 ± 0.69 seconds, and there was no difference in the average reading speed between sentences (p=0.836). The reading speed was 146.2 wpm for the right eye and 142.5 wpm for the left eye in logMAR 1.0 size, and 97.7 wpm and 99.7 wpm in logMAR 0.0 size. Reading acuity was measured as logMAR 0.0 or better in 80% of cases. All subjects showed a critical print size of 0.2 or better logMAR.Conclusion: Using the Korean version of the MNREAD acuity chart, the reading ability including reading acuity, reading speed and critical print size, can be measured. It is thought that it will be a useful tool to measure reading ability even for those who speak Korean as their native language.

A low interfacial contact resistance is a challenge in polymer nanocomposites based on conductive nanomaterials for high-performance wearable electrode applications. Herein, a polydimethylsiloxane (PDMS)-based flexible nanocomposite incorporating high-conductivity 1D single-walled carbon nanotubes (SWCNTs) and 2D reduced graphene oxide (r-GO) was developed for high-performance electrocardiogram (ECG) wearable electrodes. A PDMS-SWCNT (P-SW; type I) nanocomposite containing only SWCNTs (2 wt%), exhibited rough and non-uniform surface morphology owing to the strong bundling effect of as-grown SWCNTs and randomly entangled aggregate structures and because of inefficient vacuum degassing (

In this study, graphene was rapidly grown by chemical vapor deposition using a liquid cell for supplying methanol as a carbon source of graphene. To realize the rapid growth, methanol which is carbon-contained organic solvent was used instead of methane gas, a widely used carbon source for graphene growth. The graphene grown with the growth time as a variable was transferred to a SiO2/Si substrate with an oxide thickness of 300 nm to confirm whether it was grown with full coverage with an optical microscope. The results confirmed a full coverage in 0.5 min of growth. The Raman spectra also confirmed the G-peak position at 1585.0 cm−1 and an intensity ratio of 2D/G at 2.3 or higher. Concerning electrical transport characteristics, at an induced carrier density of 1 × 1012 cm−2, the hole (µh) and electron (µe) mobilities were 1524 cm2 V−1 s−1 and 1528 cm2 V−1 s−1, respectively. Thus, our study confirmed that high-quality, large-area graphene can be grown within 0.5 min.

In this study, we optimized the condition for forming a single-crystal (111) Cu substrate by using polycrystalline Cu and an abnormal grain growth method. As a result, a single-crystal (111) Cu surface could be formed through annealing for 2 hours in an H2 (100 sccm) and Ar (200 sccm) gas atmosphere (pressure 70 Torr) at 1050 °C. The crystallinity of the Cu-surface was confirmed by using X-ray diffraction analysis and electron backscatter diffraction (EBSD) pattern imaging and mapping. In addition, chemical vapor deposited graphene was synthesized before and after the crystallinity control of the substrate, and then transferred onto an SiO2 (300 nm)/Si substrate to perform a Raman spectral analysis and to evaluate the electrical properties through graphene field effect transistor device fabrication. In particular, the mobility of graphene grown on polycrystalline Cu is μh = 1228 (μe = 1158) cm2·V−1·s−1 while the carrier mobility of graphene synthesized on a single-crystal Cu surface is μh = 3353 (μe = 3200) cm2·V−1·s−1, showing an improvement of about 273% (276%). Such a single-crystal substrate can be widely used for the synthesis of high-quality 2-dimensional materials and can be reused after the material has been transferred by using a metal etching-free transfer method.

We report on the electroluminescent (EL) and electrical characteristics of graphene-inserted ZnO nanorods (NRs)/p-GaN heterojunction diode. In a comparative study, ZnO NRs/p-GaN and ZnO NRs/graphene/p-GaN heterojunctions exhibit white and yellow EL emissions, respectively, at reverse bias (rb) voltages. The different EL colors are results of different dichromatic EL peak intensity ratios between 2.25 and 2.8 eV light emissions which are originated from ZnO and p-GaN sides, respectively. The 2.25 eV EL is predominant in both the heterojunctions, because of recombination by numerous electrons tunneled from p-GaN to ZnO across the thin barriers of the staggered broken gap with a large band offset in ZnO/p-GaN and the van der Waals (vdW) gap formed by graphene insertion at ZnO NRs/p-GaN. However, as for the 2.8 eV EL intensity, ZnO NRs/graphene/p-GaN hardly shows the EL emission, whereas ZnO NRs/p-GaN exhibits the substantially strong EL peak. We discuss that the significantly reduced 2.8 eV EL emission of ZnO NRs/graphene/p-GaN is a result of decreased depletion layer thickness at p-GaN side where the recombination events occur for 2.8 eV EL before the reverse bias-driven tunneling because the insertion of graphene (or vdW gap barrier) inhibits the carrier diffusion whose amount determines the depletion thickness when forming the heterojunctions. This study opens a way of suppressing (or enhancing) the specific EL wavelength for the dichromatic EL-emitting heterojunctions simply by inserting atom-thick vdW layer.

The thermoelectric (TE) effect in nanoscale materials is of great interest as an ideal platform for small-scale energy harvesting and micro-cooling technologies. In this regard, two-dimensional (2D) metal dichalcogenides (TMDCs) can be considered as a promising material for TE applications owing to their superior electronic and phonon transport properties provided by a favorable large energy band gap and an atomically thin layer, which serves as an ideal quantum well structure. We investigate and conduct a direct comparison of the cross-plane Seebeck coefficients of various TMDC films prepared by using the chemical vapor deposition method. In particular, these coefficients for MoS2, WSe2, and WS2 thin films are determined to be approximately 115, 129, and 211 μV K−1 at 300 K, respectively. The chemically formed holey structure of MoS2 thin films with a thickness of ∼7 nm exhibits superior in-plane Seebeck coefficients of ∼742 μV K−1, showing strong anisotropic behavior with a ratio of ∼6.5 along in- and cross-plane directions at 300 K. Such behavior can be explained by the energy filtering effect in the holey MoS2 film in the in-plane direction. Moreover, an extremely high anisotropic ratio (∼2.4 × 108) of the power factor was observed owing to the large in-plane Seebeck coefficients and the electrical conductivity of the MoS2 films across the samples. This study is the first to assess the cross-plane Seebeck coefficients of large-scale MoS2, WS2, and WSe2 thin films at 300 K and analyze the anisotropic behavior of the MoS2 film. The results reported here confirm the importance of providing reliable Seebeck coefficient information on films formed by using TMDC materials for further application on TE devices.

A recent study found that magnetization curves for Y

The excellent physical and chemical properties of carbon nanomaterials render them suitable for application in gas sensors. However, the synthesis of carbon nanomaterials using high-temperature furnaces is time consuming and expensive. In this study, we synthesize a carbon nanomaterial using local laser-scribing on a substrate coated with a Cu-embedded polyimide (PI) thin film to reduce the processing time and cost. Spin coating using a Cu-embedded PI solution is performed to deposit a Cu-embedded PI thin film (Cu@PI) on a quartz substrate, followed by the application of a pulsed laser for carbonization. In contrast to a pristine PI solution-based PI thin film, the laser absorption of the Cu-embedded PI thin film based on Cu@PI improved. The laser-scribed carbon nanomaterial synthesized using Cu@PI exhibits a three-dimensional structure that facilitates gas molecule absorption, and when it is exposed to NO2 and NH3, its electrical resistance changes by −0.79% and +0.33%, respectively.

In this study, the rapid synthesis of graphene via chemical vapor deposition (CVD) using liquefied petroleum gas (LPG), a common and low-cost carbon source majorly composed of butane and propane, as the precursor is investigated. For the synthesis of high-quality graphene, the growth conditions are optimized by controlling CVD parameters such as growth time, temperature, gas amount, and flow rate. Thus, graphene is successfully obtained from LPG in a short time. This synthesis is 10 times faster than that the conventional synthesis using methane as the carbon source. In the X-ray photoelectron spectra, the rapidly grown graphene samples obtained from LPG show small S2p signals due to the presence of few tens ppm ethanethiol in commercial LPG. In addition, graphene is synthesized using a hydrogen and LPG mixture to investigate the quality of graphene. Both samples are characterized by their peak positions and full width at half maximum values of the G and 2D peaks in the Raman spectra and Dirac points in the electrical measurements. In particular, the Dirac points of the graphene sample obtained with a growth time of 1 min sample appear around −22 VG and the sample's mobility is about 1600 cm2/V⋅s.

We developed a new technique to fabricate single nanowire devices with reliable graphene/nanowire contacts using a position-controlled microtransfer and an embedded nanowire structure in a planar junction configuration. A thorough study of electrical properties and fabrication challenges of single p-GaAs nanowire/graphene devices was carried out in two different device configurations: (1) a graphene bottom-contact device where the nanowire-graphene contact junction is formed by transferring a nanowire on top of graphene and (2) a graphene top-contact device where the nanowire-graphene contact junction is formed by transferring graphene on top of an embedded nanowire. For the graphene top-contact devices, graphene-nanowire-metal devices, where graphene is used as one electrode and metal is the other electrode to a nanowire, and graphene-nanowire-graphene devices, where both electrodes to a nanowire are graphene, were investigated and compared with conventional metal/p-GaAs nanowire devices. Conventional metal/p-GaAs nanowire contact devices were further investigated in embedded and nonembedded nanowire device configurations. A significantly improved current in the embedded device configuration is explained with a "parallel resistors model" where the high-resistance parts with the metal-semiconductor Schottky contact and the low-resistance parts with noncontacted facets of the hexagonal nanowires are taken into consideration. Consistently, the nonembedded nanowire structure is found to be depleted much easier than the embedded nanowires from which an estimation for a fully depleted condition has also been established.

The physical properties of nano-sized metal oxide semiconductors are influenced by the nanostructures as well as the crystallinity, thus the growth of crystalline tin oxide (SnO) with controlled morphologies would be important to its applications. To date, the various morphologies of SnO have been successfully synthesized such as nanodisks, nanobelts, nanoplatelets, nanoslabs, nanoflowers, and nanobranches. Here, the vertical free-standing SnO nanostructures were densely grown on single layer graphene (SLG) by vapor transport method. Compared with the tilted SnO nanostructures on SiO2/Si substrate, surface area ratio of the free-standing SnO nanostructures exhibit over of 4.4 times. According to analysis results such as Raman spectroscopy, FE-SEM, XRD, and FE-TEM, uniform and high quality free-standing SnO nanostructures were grown on large area SLG. We observed that the synthetic shapes of SnO nanostructures are different depending on the presence or absence of graphene film on substrate.

Carbon nanomaterials have attracted significant research attention as core materials in various industrial sectors owing to their excellent physicochemical properties. However, because the preparation of carbon materials is generally accompanied by high-temperature heat treatment, it has disadvantages in terms of cost and process. In this study, highly sensitive carbon nanomaterials were synthesized using a local laser scribing method from a copper-embedded polyacrylonitrile (CuPAN) composite film with a short processing time and low cost. The spin-coated CuPAN was converted into a carbonization precursor through stabilization and then patterned into a carbon nanomaterial of the desired shape using a pulsed laser. In particular, the stabilization process was essential in laser-induced carbonization, and the addition of copper promoted this effect as a catalyst. The synthesized material had a porous 3D structure that was easy to detect gas, and the resistance responses were detected as −2.41 and +0.97% by exposure to NO2 and NH3, respectively. In addition, the fabricated gas sensor consists of carbon materials and quartz with excellent thermal stability, therefore, it is expected to operate as a gas sensor even in extreme environments.

The flux-weighted average cross-sections of $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}}){}^{{159,157,155}}{\mathrm {Dy}}$$ reactions were measured at the bremsstrahlung end-point energies of 12, 14, 16, 65 and 75 MeV with the activation and off-line $$\upgamma $$ -ray spectrometric technique using the 20 MeV Electron Linac for beams with high Brilliance and low Emittance (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany and the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}}){}^{{157,155}}{\mathrm {Dy}}$$ reaction cross-sections as a function of photon energy were also calculated theoretically using TALYS 1.9 code. Then the flux-weighted average values at different end-point energies were obtained based on the theoretical values of mono-energetic photons. These values were compared with the flux-weighted values of present work and are found to be in general agreement. It was also found that the experimental and theoretical formation cross sections of $${}^{159}{\mathrm {Dy}}$$ , $${}^{157}{\mathrm {Dy}}$$ and $${}^{155}{\mathrm {Dy}}$$ from the $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}})$$ reactions increased from their respective threshold values to a certain energy where other reaction channels opened. After reaching a maximum value, the individual reaction cross-sections slowly decreased with the increase of the bremsstrahlung energy due to the initiation of other competing reactions at higher energy, which indicates the impact of the excitation energy. However, the production cross sections of $${}^{157}{\mathrm {Dy}}$$ and $${}^{155}{\mathrm {Dy}}$$ from the $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}})$$ reactions slightly increase in between and then decreased slowly with bremsstrahlung energy, which is due to the contributing reactions of higher mass isotopes.

Seawater battery, which consists of a Na metal anode and a seawater cathode, has highly attractive features because of its eco-friendliness in use of seawater and cost-effectiveness in the use of Na, the 6th most abundant element of the Earth's crust. Herein, we demonstrate a reliable Na metal anode for the seawater battery by covering the Cu current collector with a graphene monolayer. The surface of the chemically uniform graphene-coated current collector facilitates control of the nucleation rate of surficial Na metal at the initial stage and enhances the coulombic efficiency in current collector|separator|Na metal cells by lowering the nucleation and plating potentials. Further deliberate modification of the graphene surface by using O2 plasma and thermal treatments supports the significance of the homogeneity of the interface of the current collector. Problematically, heterogeneous Cu surfaces covered with islands of oxide layers significantly altered the surface morphology of plated Na metal and consequently resulted in the decrease in electrochemical performance due to the impeding effect on Na ion diffusion near the current collector surface. Through successful implantation of the graphene-coated Cu current collector as an anode in the seawater battery, the battery performance drastically improved, which was confirmed by monitoring the discharge/charge performance and durability of LED lighting.

We report the controllable pore structures of pure (>99.5 wt%) and sub-millimeter-long single-walled and few-walled (triple-walled on average) carbon nanotubes (SWCNTs and FWCNTs, respectively) synthesized via fluidized-bed chemical vapor deposition. The pore structures and adsorption properties of the CNTs were characterized using N2 adsorption analysis at 77 K. A significant advantage of the synthesized vertically-aligned SWCNTs (diameter range: 2–4 nm) and FWCNTs (diameter range: 4–8 nm) arrays, having small bundle structures, is that the guest molecules can easily access the external surfaces of the CNTs, leading to high specific surface areas (SSAs; 903 and 337 m2 g−1, respectively) and pore volumes (2.56 and 2.05 mL g−1, respectively). Interestingly, following sonication, the SSAs of the SWCNTs and FWCNTs increased by 36% and 41%, respectively. Additionally, after mixed acid (HNO3/H2SO4) treatment, the SSAs of the SWCNTs and FWCNTs increased by 34% and 120%, respectively, which are attributed to the corresponding increases in the micropore and mesopore SSAs. These results suggest that CNT networks with controllable pore structures can be fabricated by altering the diameter distribution and alignment degree of the CNTs, thus highlighting the potential of our approach to develop cost-effective CNT-based structures for applications such as high-performance energy storage materials.

Low-pressure chemical vapor deposition of graphene has been investigated on various Pt substrates such as e-beam deposited films, sputtered films, and polycrystalline foils. High temperature sputtering is found to be crucial in growing single layer graphene on Pt. It gives highly (111)-oriented crystallization with a significant reduction of dewetting in Pt films, in contrast to e-beam deposited Pt films. Graphene grown on high temperature sputtered Pt films is free of micro-sized multilayer graphene islands normally observed in graphene grown on polycrystalline Pt foils. This indicates that using Pt thin films can effectively suppress the multilayer graphene growth by carbon segregations and precipitations from the Pt bulk. Growth of single layer graphene is demonstrated on Pt films with a thickness down to 25 nm. Effects of the Pt substrates on the as-grown graphene have been investigated. An XY plot of the Raman G and 2D bands in graphene shows a correlation with the surface facet orientations of the Pt substrates measured by electron backscatter diffraction. With a general red shift of the G band distributions, a blue shift of the 2D band distributions is observed, which goes as high as ∼2750 cm−1 in graphene grown on Pt (111) films.

We synthesize a series of CVD h-BN films and perform critical infrared spectroscopic characterization. For high-temperature (HT, Temp = 1400 degrees) grown h-BN thin film only E1u-mode infrared phonon is activated demonstrating highly aligned 2D h-BN planes over large area, whereas low-temperature (LT, Temp = 1000 degrees) grown film shows two phonon peaks, E1u and A2u, due to stacking of h-BN plane at tilted angle. For CVD graphene transferred on HT h-BN/SiO2/Si substrate, interband transition spectrum s1 shifts strongly to lower energy compared with that on LT h-BN/SiO2/Si and on bare SiO2/Si substrate, revealing that residual carrier density n in graphene is suppressed by use of HT h-BN layer. Also the interband transition width of s1 defined by effective temperature is reduced from 400 K for G/SiO2/Si to 300 K for HT h-BN/SiO2/Si. The behaviors of n and effective temperature show that HT h-BN film can decouple CVD graphene from the impurity and defect of SiO2 leading to large scale free-standing like graphene., 5 pages, 4 figures

We investigated the heat transfer behavior of thermally conductive networks with one-dimensional carbon materials to design effective heat transfer pathways for hybrid filler systems of polymer matrix composites. Nano-sized few-walled carbon nanotubes (FWCNTs) and micro-sized mesophase pitch-based carbon fibers (MPCFs) were used as the thermally conductive materials. The bulk density and thermal conductivity of the FWCNT films increased proportionally with the ultrasonication time due to the enhanced dispersibility of the FWCNTs in an ethanol solvent. The ultrasonication-induced densification of the FWCNT films led to the effective formation of filler-to-filler connections, resulting in improved thermal conductivity. The thermal conductivity of the FWCNT-MPCF hybrid films was proportional to the MPCF content (maximum thermal conductivity at an MPCF content of 60 wt %), indicating the synergistic effect on the thermal conductivity enhancement. Moreover, the MPCF-to-MPCF heat transfer pathways in the FWCNT-MPCF hybrid films were the most effective in achieving high thermal conductivity due to the smaller interfacial area and shorter heat transfer pathway of the MPCFs. The FWCNTs could act as thermal bridges between neighboring MPCFs for effective heat transfer. Furthermore, the incorporation of Ag nanoparticles of approximately 300 nm into the FWCNT-MPCF hybrid film dramatically enhanced the thermal conductivity, which was closely related to a decreased thermal interfacial resistance at the intersection points between the materials. Epoxy-based composites loaded with the FWCNTs, MPCFs, FWCNT-MPCF hybrids, and FWCNT-MPCF-Ag hybrid fillers were also fabricated. A similar trend in thermal conductivity was observed in the polymer matrix composite with carbon-based hybrid films.

A finite Schottky barrier and large contact resistance between monolayer MoS2 and electrodes are the major bottlenecks in developing high-performance field-effect transistors (FETs) that hinder the study of intrinsic quantum behaviors such as valley-spin transport at low temperature. A gate-tunable graphene electrode platform has been developed to improve the performance of MoS2 FETs. However, intrinsic misalignment between the work function of pristine graphene and the conduction band of MoS2 results in a large threshold voltage for the FETs, because of which Ohmic contact behaviors are observed only at very high gate voltages and carrier concentrations (~1013 cm-2). Here, we present high-performance monolayer MoS2 FETs with Ohmic contact at a modest gate voltage by using a chemical-vapor-deposited (CVD) nitrogen-doped graphene with a high intrinsic electron carrier density. The CVD nitrogen-doped graphene and monolayer MoS2 hybrid FETs platform exhibited a large negative shifted threshold voltage of -54.2 V and barrier-free Ohmic contact under zero gate voltage. Transparent contact by nitrogen-doped graphene led to a 214% enhancement in the on-current and a four-fold improvement in the field-effect carrier mobility of monolayer MoS2 FETs compared with those of a pristine graphene electrode platform. The transport measurements, as well as Raman and X-ray photoelectron spectroscopy analyses before and after thermal annealing, reveal that the atomic C-N bonding in the CVD nitrogen-doped graphene is responsible for the dominant effects of electron doping. Large-scale nitrogen-doped graphene electrodes provide a promising device platform for the development of high-performance devices and the study of unique quantum behaviors., 25 pages, 4 figures

The electrochemical performance of sulfur-doped carbon nanotubes (S-CNTs) was investigated to confirm the S-doping effects and the possibility of their application as conducting agents in supercapacitor electrodes. S-CNTs were successfully synthesized via chemical vapor deposition using dimethyl disulfide as the carbon source. They were purified to obtain purified S-CNTs (P–S-CNTs) with diameters 30–50 nm and S content of 0.65 at%. The doped S atoms were removed partially from the P–S-CNTs by heat treatment in H2 atmosphere (De-P-S-CNTs). To compare the electrochemical performances of various conducting materials for supercapacitor electrodes, commercial activated carbon (MSP20) was used as the active material and commercial conducting agent (Super-P), commercial multi-walled CNTs (MWCNTs), De-P-S-CNTs, and P–S-CNTs were used as the conducting agents. The electrode with P–S-CNTs exhibited the highest specific capacitance at a high discharge current density of 100 mA cm−2 (120.2 F g−1) and the lowest charge-transfer resistance (6.19 Ω) that are significantly superior to those of Super-P (83.9 F g−1 and 15.16 Ω), MWCNTs (87.8 F g−1 and 17.02 Ω), and De-P-S-CNTs (90.1 F g−1 and 22.33 Ω). The superior electrochemical performance of P–S-CNTs can be attributed to the excellent electrical conductivity and pseudocapacitive contribution of the S-doping effect.

Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln0.5Sr0.5Ti0.5Mn0.5O3±d (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln0.5Sr0.5Ti0.5Mn0.5O3±d were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln0.5Sr0.5Ti0.5Mn0.5O3±d; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln0.5Sr0.5Ti0.5Mn0.5O3±d, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln0.5Sr0.5Ti0.5Mn0.5O3±d from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd0.5Sr0.5Ti0.5Mn0.5O3±d (NSTM) and Sm0.5Sr0.5Ti0.5Mn0.5O3±d (SSTM). In various respects, NSTM and SSTM will be desirable reforming catalysts and anode candidates for high temperature solid oxide fuel cell.

We use the graphene as a passivation layer to protect the black phosphorus from chemical reaction with air. Flakes of the black phosphorus crystal are covered by N = 1, 2, and 3 layers of CVD graphene and the Raman phonon modes are measured after the samples are exposed to air. For the double and triple layer passivation (N = 2,3) the Raman phonon peaks are maintained as long as ∼100 h (4 days) before the phonon intensity is reduced to 90% of the initial strength, I/I 0 = 0.9, demonstrating that the black phosphorus is strongly protected in contrast to the rapid degradation of the bare and single-layer covered black phosphorus. The long term stability achieved by multi-layer graphene passivation makes it possible to perform various electronic and optical experiments aimed for device application of this direct-gap van der Waals semiconductor with high electronic and thermal mobility under ambient environment.

We demonstrate controlled growth of vertical organic crystal nanowires on single layer graphene. Using Scanning Electron Microscopy (SEM), high-resolution transmission electron microscopy (TEM), and Grazing Incidence X-ray Diffraction (GIXD), we probe the microstructure and morphology of dibenzotetrathienocoronene (DBTTC) nanowires epitaxially grown on graphene. The investigation is performed at both the ensemble and single nanowire level, and as a function of growth parameters, providing insight of and control over the formation mechanism. The size, density and height of the nanowires can be tuned via growth conditions, opening new avenues for tailoring three-dimensional (3-D) nanostructured architectures for organic electronics with improved functional performance.

Over the past decades, graphene has attracted much attention from the scientific community due to its broad applications in the optoelectronics industries [1]. Owing to graphene's high transmission and high electrical conductivity, diverse functional materials/graphene hybridized heterostructures and interfaces are under extensive investigation to satisfy the increasing interest in the need for bendable, flexible and high performance optoelectronic devices [2]. Due to the good atomic lattice structure of graphene, varying heterostructures have been formed by depositing different functional materials directly on graphene [3], [4], [5]. We fabricated a vertical photovoltaic type G/PbS/Ti device by making use of the Ti/PbS Schottky junction and discussed the photocurrent transient characteristics. Lead sulfide (PbS) was deposited directly on large area CVD (Chemical vapor deposition) graphene by CBD (Chemical bath deposition). Temperature dependent photocurrent spectra of our G/PbS/Ti photovoltaic devices were measured by a Fourier transformed infrared (FTIR) set-up. In this paper, we present the experimental procedures and the raw experimental data for the direct chemical deposition of PbS on CVD-graphene for high performance photovoltaic infrared photo-detectors. The manuscript is already available [6].

The need for bendable, flexible and high performance optoelectronic devices has led to various functional materials/graphene hybridized structures. PbS thin films were successfully synthesized by chemical bath deposition (CBD) method directly on large area CVD-graphene and strong preferential growth of PbS along [2 0 0] was obtained. We fabricated vertical type Ti/PbS photovoltaic devices with graphene and discussed their photocurrent transient characteristics. Photocurrent spectra of graphene/Ti/PbS device were recorded at 0 V at various temperatures using a Fourier transform infrared (FTIR) spectrometer.

One of the most prominent and effective applications of graphene in the field of spintronics is its use as a spacer layer between ferromagnetic metals in vertical spin valve devices, which are widely used as magnetic sensors. The magnetoresistance in such devices can be enhanced by a selection of suitable spacer materials and proper fabrication procedures. Here, we report the use of dry-transferred single- and double-layer graphene, grown by chemical vapor deposition (CVD), as the spacer layer and the fabrication procedure in which no photo-resist or electron-beam resists is used. The measured maximum magnetoresistance of NiFe/CVD-Graphene/Co junction is 0.9% for the single- and 1.2% for the double-layer graphene at 30 K. The spin polarization efficiency of the ferromagnetic electrodes is about 6.7% and 8% for the single- and the double-layer graphene, respectively, at the same temperature. The bias-independent magnetoresistance rules out any contamination and oxidation of the interfaces between the ferromagnet and the graphene. The magnetoresistance measured as a function of tilted magnetic field at different angles showed no changes in the maximum value, which implies that the magnetoresistance signal is absent from anisotropic effects.

Recently, two-dimensional tungsten disulfide (WS2) has attracted attention as a next generation thermoelectric material due to a favorable Seebeck coefficient. However, its thermoelectric efficiency still needs to be improved due to the intrinsically low electrical conductivity of WS2. In the present study, thermoelectric properties of WS2 hybridized with highly conductive single-walled carbon nanohorns (SWCNHs) were investigated. The WS2/SWCNH nanocomposites were fabricated by annealing the mixture of WS2 and SWCNHs using a high-frequency induction heated sintering (HFIHS) system. By adding SWCNHs to WS2, the nanocomposites exhibited increased electrical conductivity and a slightly decreased Seebeck coefficient with the content of SWCNHs. Hence, the maximum power factor of 128.41 &mu, W/mK2 was achieved for WS2/SWCNHs with 0.1 wt.% SWCNHs at 780 K, resulting in a significantly improved thermoelectric figure of merit (zT) value of 0.027 compared to that of pristine WS2 with zT 0.017.

The present study investigates the atomic layer deposition (ALD) of an Al2O3 film on graphene atop copper with water vapor (H2O), oxygen plasma (O2 plasma) and ozone (O3) serving as oxidants. With water vapor as an oxidant, surface-sensitive deposition results in significant differences in growth on single layer graphene (SLG) and multilayer graphene (MLG). Al2O3 completely covers areas of SLG, while virtually no Al2O3 is deposited on areas of MLG. The MLG areas are removed by O2 plasma, and exposed copper areas are oxidized. Information about MLG, including the location, size, and density, can be determined by employing optical microscopy. Scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) are used to confirm the validity of the surface-selective deposition of Al2O3 on graphene grown on copper. We developed a process to distinguish SLG and MLG on copper. The characterization results were fed back to the synthesis conditions, and we confirmed that high-quality SLG can be grown on copper almost devoid of MLG. This characterization technique is suitable for large-area graphene (up to meter scale graphene), and can be utilized as feedback for growth and process conditions to ensure high-quality graphene.