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THE BINDER SOLUTION FOR ALL SOLID STATE BATTERY
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GRAPHENE OXIDE DERIVATIVE AND METHOD FOR FABRICATING THE SAME
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Comparison of characteristics and sources of water-soluble inorganic ions, trace elements, and polycyclic aromatic hydrocarbons in PM2.5 on polluted and normal days in Ulsan, South Korea
No full textPM2.5 samples were collected from a semi-rural site in the industrial city of Ulsan, South Korea during 2018-2019 to characterize the chemical composition and determine source contributions on polluted and normal days. The daily PM2.5 concentration exceeded the United States National Ambient Air Quality Standards (35 mu g/m(3)) on 11 of the 56 days. The mean concentration of sigma(9) water-soluble inorganic ions (WSIIs) was 17.1 and 6.07 mu g/m(3) on polluted and normal days, respectively, with SO42-, NO3-, and NH4+ the dominant species. The elements were dominated by Mg and Fe, with a mean concentration of sigma(11) elements of 1973 and 855 ng/m(3) on polluted and normal days, respectively. The mean concentration of sigma(21) polycyclic aromatic hydrocarbons (PAHs) was 4.44 and 3.26 ng/m(3) on polluted and normal days, respectively, indicating a higher human health risk on polluted days. High PM2.5 concentrations were due to an increase in the concentration of almost all WSIIs, elements, and PAHs on polluted days. Potential sources of PM2.5 were identified using positive matrix factorization (PMF), the conditional bivariate probability function (CBPF), and the potential source contribution function (PSCF). According to PMF results, secondary inorganic aerosols (39.8%), primary sulfate (18.2%), and coal/biomass burning (16.3%) were dominant on polluted days, whereas marine sources (23.1%), secondary inorganic aerosols (19.3%), and primary sulfate (16.2%) were the largest contributors to PM2.5 on normal days. Results from the CBPF and PSCF indicate that polluted days may be influenced by both long-range atmospheric transport (LRAT) and local emission sources, while LRAT became more important on normal days. Based on these findings, other studies are necessary to further investigate and distinguish the PM2.5 source contributions in industrial and urban areas
Remarkable Electrical Conductivity Increase and Pure Metallic Properties from Semiconducting Colloidal Nanocrystals by Cation Exchange for Solution-Processable Optoelectronic Applications
No full textThe authors report a strategic approach to achieve metallic properties from semiconducting Cu-Fe-S colloidal nanocrystal (NC) solids through cation exchange method. An unprecedentedly high electrical conductivity is realized by the efficient generation of charge carriers onto a semiconducting Cu-S NC template via minimal Fe exchange. An electrical conductivity exceeding 10 500 S cm(-1) (13 400 S cm(-1) at 2 K) and a sheet resistance of 17 omega/sq at room temperature, which are among the highest values for solution-processable semiconducting NCs, are achieved successfully from bornite-phase Cu-Fe-S NC films possessing 10% Fe atom. The temperature dependence of the corresponding films exhibits pure metallic characteristics. Highly conducting NCs are demonstrated for a thermoelectric layer exhibiting a high power factor over 1.2 mW m(-1)K(-2) at room temperature, electrical wires for switching on light emitting diods (LEDs), and source-drain electrodes for p- and n-type organic field-effect transistors. Ambient stability, eco-friendly composition, and solution-processability further validate their sustainable and practical applicability. The present study provides a simple but very effective method for significantly increasing charge carrier concentrations in semiconducting colloidal NCs to achieve metallic properties, which is applicable to various optoelectronic devices
Controlled growth of perovskite layers with volatile alkylammonium chlorides
No full textControlling the crystallinity and surface morphology of perovskite layers by methods such as solvent engineering(1,2) and methylammonium chloride addition(3-7) is an effective strategy for achieving high-efficiency perovskite solar cells. In particular, it is essential to deposit a-formamidinium lead iodide (FAPbI(3)) perovskite thin films with few defects due to their excellent crystallinity and large grain size. Here we report the controlled crystallization of perovskite thin films with the combination of alkylammonium chlorides (RACl) added to FAPbI(3). The d-phase to a-phase transition of FAPbI(3) and the crystallization process and surface morphology of the perovskite thin films coated with RACl under various conditions were investigated through in situ grazing-incidence wide-angle X-ray diffraction and scanning electron microscopy. RACl added to the precursor solution was believed to be easily volatilized during coating and annealing owing to dissociation into RA(0) and HCl with deprotonation of RA(+) induced by RAMIDLINE HORIZONTAL ELLIPSISH+-Cl- binding to PbI2 in FAPbI(3). Thus, the type and amount of RACl determined the d-phase to a-phase transition rate, crystallinity, preferred orientation and surface morphology of the final a-FAPbI(3). The resulting perovskite thin layers facilitated the fabrication of perovskite solar cells with a power-conversion efficiency of 26.08% (certified 25.73%) under standard illumination
Advanced Dry Etch Process with Low Global Warming Potential Gases Toward Carbon Neutrality
No full textCurrently, semiconductor manufacturing industry heavily relies on a wide range of high global warming potential (GWP) gases, particularly during etching and cleaning processes, and their use and relevant carbon emissions are subject to global rules and regulations for achieving carbon neutrality by 2050. To replace high GWP gases in near future, dry etching using alternative low GWP gases is thus being under intense investigations. In this review, we report a current status and recent progress of the relevant research activities on dry etching processes using a low GWP gas. First, we review the concept of GWP itself and then introduce the difference between high and low GWP gases. Although most of the studies have concentrated on potentially replaceable additive gases such as C4F8, an ultimate solution with a lower GWP for main etching gases including CF4 should be developed; therefore, we provide our own perspective in this regard. Finally, we summarize the advanced dry etch process research with low GWP gases and list up several issues to be considered in future research
Quantitative Two-Stage Classification of Gas Mixtures Using 2D TMDC and PGM Chalcogenides
No full textAccurate and quantitative classification of gas mixtures is an important issue in various fields, including the healthcare and food industries. However, traditional classification approaches such as gas chromatography, mass spectroscopy, and chemical analysis not only require specialized skills but are also time-consuming, inaccurate, and expensive. For these reasons, we used a chemiresistive sensor based on 2D transition metal dichalcogenides and platinum group material based chalcogenides, which have high responsivity, selectivity, and stability toward target gases. Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the WS2 and RuS2 sensing channels. Moreover, the gas-sensing properties toward NO2, NH3, and their mixtures (1:1 and 2:1) were analyzed, and the classification of these gases was carried out via our proposed two-stage classification model consisting of dimensionality reduction and classification processes. The proposed model achieved more than 90 % accuracy in all cases when classifying single gases and their mixtures, which could be industrially applicable in the future. IEE
Leachability of Lead, Cadmium, and Antimony in Cement Solidified Waste in a Silo-Type Radioactive Waste Disposal Facility Environment
No full textThe waste acceptance criteria for heavy metals in mixed waste should be developed by reflecting the leaching behaviors that could highly depend on the repository design and environment surrounding the waste. The current standards widely used to evaluate the leaching characteristics of heavy metals would not be appropriate for the silo-type repository since they are developed for landfills, which are more common than a silo-type repository. This research aimed to explore the leaching behaviors of cementitious waste with Pb, Cd, and Sb metallic and oxide powders in an environment simulating a silo-type radioactive waste repository. The Toxicity Characteristic Leaching Procedure (TCLP) and the ANS 16.1 standard were employed with standard and two modified solutions: concrete-saturated deionized and underground water. The compositions and elemental distribution of leachates and specimens were analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) and energy-dispersive X-ray spectroscopy combined with scanning electron microscopy (SEM-EDS). Lead and antimony demonstrated high leaching levels in the modified leaching solutions, while cadmium exhibited minimal leaching behavior and remained mainly within the cement matrix. The results emphasize the significance of understanding heavy metals' leaching behavior in the repository's geochemical environment, which could accelerate or mitigate the reaction