Search

Two-dimensional (2D) transition metal dichalcogenide (TMDC) materials are indispensable candidates for thermoelectric (TE) device applications. However, thermal transport at low temperatures, as an important TE device application, has not been fully realized, especially in large-area 2D TMDC films. Here, we report temperature-dependent in-plane Seebeck coefficients, along with electrical and thermal conductivities, of both 3 nm-thick PtSe2 films and stacked 2D/2D semiconducting PtSe2/PtSe2 (3 nm/3 nm) homostructures at temperatures ranging from 40 to 300 K using a homemade Seebeck coefficient measurement module and a heat diffusion imaging method, respectively. In the single 2D PtSe2 (3 nm) film, simultaneous decreases in the in-plane Seebeck coefficient and electrical conductivity were observed with decreasing temperature, indicating the presence of both semiconductor and metallic properties. At 300 K, the in-plane Seebeck coefficient of the single 2D PtSe2 film is ∼65.1 μV K−1, whereas those of the 2-, 3-, and 4-stacked PtSe2/PtSe2 homostructures are ∼69.1, ∼79.0 and ∼72.0 μV K−1, respectively due to interface formation between the PtSe2 layer. The in-plane thermal conductivity of the single PtSe2 film is ∼28.3 W m−1 K at 300 K and reaches maximum values of ∼98.5 and ∼12.1 W m−1 K at 97 and 42 K, respectively. Our findings demonstrate the feasibility of utilizing 2D semiconducting PtSe2 layers with interface formation between the 2D layers as TE energy-saving and energy-generating devices, as they exhibit the TE properties required by an ideal TE material. [ABSTRACT FROM AUTHOR]

Gallium‐based liquid metal, eutectic gallium–indium alloy (EGaIn), is becoming a leading innovation in soft electronic devices due to its exceptional electronic conductivity and deformability. However, the formation of insulating oxide films on EGaIn surfaces poses a significant impediment to translating electrochemical reactions, thereby limiting its use as an electrochemical biosensor. Here, functionalized EGaIn electrodes with reduced‐graphene‐oxide assembled EGaIn core–shell particles (REGs) for soft and deformable electrochemical biosensors are presented. Exploiting EGaIn's capability as a reducing agent, REGs can undergo further modification with metal nanoparticles through additional galvanic replacement reactions. The REGs and metal‐coated REGs (M‐REGs) provide strong interfacial adhesion with the EGaIn current collector, exhibiting no exfoliation during and after the mechanical deformation. Moreover, RIDE and metal‐decorated RIDE (M‐RIDE) show excellent electrochemical sensing performances by taking advantage of the facile surface tunability of REGs, allowing simultaneous detection of ascorbic acid, dopamine, and uric acid, and enzymatic detection of glucose. The developed RIDE/M‐RIDE paves the way for utilizing EGaIn in the development of soft and deformable electrochemical biosensors. [ABSTRACT FROM AUTHOR]

In this study, a Y2O3 insulator was fabricated via the sol–gel process and the effect of precursors and annealing processes on its electrical performance was studied. Yttrium(III) acetate hydrate, yttrium(III) nitrate tetrahydrate, yttrium isopropoxide oxide, and yttrium(III) tris (isopropoxide) were used as precursors, and UV/ozone treatment and high-temperature annealing were performed to obtain Y2O3 films from the precursors. The structure and surface morphologies of the films were characterized via grazing-incidence X-ray diffraction and scanning probe microscopy. Chemical component analysis was performed via X-ray spectroscopy. Electrical insulator characteristics were analyzed based on current density versus electrical field data and frequency-dependent dielectric constants. The Y2O3 films fabricated using the acetate precursor and subjected to the UV/ozone treatment showed a uniform and flat surface morphology with the lowest number of oxygen vacancy defects and unwanted byproducts. The corresponding fabricated capacitors showed the lowest current density (Jg) value of 10−8 A/cm2 at 1 MV/cm and a stable dielectric constant in a frequency range of 20 Hz–100 KHz. At 20 Hz, the dielectric constant was 12.28, which decreased to 10.5 at 105 Hz. The results indicate that high-quality, high-k insulators can be fabricated for flexible electronics using suitable precursors and the suggested low-temperature fabrication methods. [ABSTRACT FROM AUTHOR]

Herein, sol–gel-processed Y2O3 resistive random-access memory (RRAM) devices were fabricated. The top electrodes (TEs), such as Ag or Cu, affect the electrical characteristics of the Y2O3 RRAM devices. The oxidation process, mobile ion migration speed, and reduction process all impact the conductive filament formation of the indium–tin–oxide (ITO)/Y2O3/Ag and ITO/Y2O3/Cu RRAM devices. Between Ag and Cu, Cu can easily be oxidized due to its standard redox potential values. However, the conductive filament is easily formed using Ag TEs. After triggering the oxidation process, the formed Ag mobile metal ions can migrate faster inside Y2O3 active channel materials when compared to the formed Cu mobile metal ions. The fast migration inside the Y2O3 active channel materials successfully reduces the SET voltage and improves the number of programming–erasing cycles, i.e., endurance, which is one of the nonvolatile memory parameters. These results elucidate the importance of the electrochemical properties of TEs, providing a deeper understanding of how these factors influence the resistive switching characteristics of metal oxide-based atomic switches and conductive-metal-bridge-filament-based cells. [ABSTRACT FROM AUTHOR]

Lacquer sap has been traditionally used in coatings and artwork. Suitable types of lacquer are required to preserve and restore artifacts. Recently, unsuitable cashew nut shell liquid (CNSL) has often been mixed with lacquer sap, so it is necessary to identify the characteristics of lacquer sap by the production area. However, research is still focused on urushiol and laccol. In this study, Myanmarese lacquer sap collected from Gluta usitata, which contains thitsiol as the main component, was analyzed by HPLC to quantify thitsiol using the standards 3-(10-phenyldecyl) benzene-1,2-diol (thitsiol 16) and 3-(8Z,11Z-pentadecadienyl)-benzenediol (urushiol 15:2) as markers, and calibration curves were plotted. The coefficients of determination (R2) for thitsiol 16 and urushiol 15:2 were 0.9985 and 0.9983, respectively. In addition, a blind test was conducted to confirm that accurate quantitative analysis was possible even when Myanmarese lacquer was mixed with lacquer from another production area, which contained urushiol as the main component, and CNSL, which contained cardol, a completely different catechol. Quantitative analysis of thitsiol 16 and urushiol 15:2 in Myanmarese lacquer using HPLC can be used to evaluate the quality of lacquer sap and for more sophisticated activities such as restoration by classifying differences in lacquer sap by the production area. [ABSTRACT FROM AUTHOR]

The use of nuclear energy is inevitable to reduce the dependence on fossil fuels in the energy sector. High-temperature gas-cooled reactors (HTGRs) are considered as a system suitable for the purpose of reducing the use of fossil fuels. Furthermore, eco-friendly mass production of hydrogen is crucial because hydrogen is emerging as a next-generation energy carrier. The unit cost of hydrogen production by the levelized cost of energy (LCOE) method varies widely depending on the energy source and system configuration. In this study, energy, exergy, and thermoeconomic analyses were performed on the hydrogen production system using the HTGR and high-temperature water-cooled nuclear reactor (HTWR) to calculate reasonable unit cost of the hydrogen produced using a thermoeconomic method called modified production structure analysis (MOPSA). A flowsheet analysis was performed to confirm the energy conservation in each component. The electricity generated from the 600 MW HTGR system was used to produce 1.28 kmol/s of hydrogen by electrolysis to split hot water vapor. Meanwhile, 515 MW of heat from the 600 MW HTWR was used to produce 8.10 kmol/s of hydrogen through steam reforming, and 83.6 MW of electricity produced by the steam turbine was used for grid power. The estimated unit cost of hydrogen from HTGR is approximately USD 35.6/GJ with an initial investment cost of USD 2.6 billion. If the unit cost of natural gas is USD 10/GJ, and the carbon tax is USD 0.08/kg of carbon dioxide, the unit cost of hydrogen produced from HTWR is approximately USD 13.92/GJ with initial investment of USD 2.32 billion. The unit cost of the hydrogen produced in the scaled-down plant was also considered. [ABSTRACT FROM AUTHOR]