Cation Elements Research Articles

Ecofriendly and low-cost high-entropy sulfides with high thermal stability and ZT > 1 via entropy engineering and anion compensation

The thermoelectric performance and thermal stability of high-entropy sulfides (Cu7Mg2Sn2ZnGeS13, Cu5MgSnZnSiS9, and Cu7Mg2Sn2ZnSiS13) were studied and compared with copper-based monosulfides (Cu2S) and binary sulfides (Cu12Sb4S13). High-entropy sulfides exhibit superior thermal stability, characterized by higher decomposition onset temperatures and minimal weight loss, maintaining their structural stability up to 750 ℃. Cu7Mg2Sn2ZnSiS13 demonstrates a peak ZT of 0.52 at 500 ℃. Further optimization through sulfur compensation (Cu7Mg2Sn2ZnSiS13.5) results in a 200 % improvement of the peak ZT value to 1.12 at 550 ℃, which is comparable to other pristine copper-based sulfides, while being more eco-friendly and cost-effective. Entropy engineering provides a new way to improve the inherent thermal and structural stability of sulfides and can also optimize their thermoelectric performance using non-toxic and earth abundant cation elements.

Dendrometrical Structure and Physicochemical Analysis of Mangrove Sediments from the Nyong River Estuary (Cameroon, Atlantic Coast)

Mangrove estuaries are not immune to the threats posed by climate and anthropogenic constraints on aquatic environments. In the Nyong River estuary, mangrove ecotone has capital importance for biodiversity conservation due to its localization in the Douala-Edéa protected area. For this study, seven quadrats were delimited in aim to evaluate mangrove structure and assessed his interplay with sediment and water physicochemical characteristics. The study revealed a total of 120 individuals of 4 regularly encountered species over a distance of 14 km: <i>Rhizophora racemosa, Avicennia germinans, Rhizophora harrisonii </i>and <i>Phoenix reclinata</i> palms. The marshy soils under the mangrove have Total Nitrogen percentages varying between 0.04 and 0.68%. Total Organic Carbon (from 2.20 to 8.61%) and Total Organic Matter (from 3.66 to 14.64%) contents have a similar pattern. The ratios of Carbon and Nitrogen (C/N) reflect the presence of organic matter and plant debris over a large proportion of the estuary. The ratio of Nitrogen and Phosphate (N/P) reflects the low availability of nitrogen in relation to phosphorus. The cation elements evolve on average in the order Ca<sup>2+</sup> ˃Mg<sup>2+</sup> ˃Na<sup>+</sup> ˃K<sup>+</sup>. This study provides information that would help explore linkages for future research on biogeochemical balance in mangrove sediment and their implementation.

Laboratory synthesis, spectroscopic characteristics, and conversion relationships of five calcium sulfate double salts relevant to Mars

Calcium sulfate veins have been found in Gale crater and Endeavour crater as indicators of Martian fluid events. The presence of mixed-cation sulfates has been suggested because a wide variety of sulfates containing different cation elements have been detected in in-situ exploration targets (e.g., soils, drilled materials, calcium sulfate veins, and sandstones). In order to establish a spectroscopic library of mixed-cation sulfates, five calcium sulfate double salts (CSDS) were successfully synthesized using high-temperature solid phase reaction and aqueous solution precipitation methods. The phase and homogeneity of these samples were confirmed by X-ray diffraction (XRD). Raman, mid-infrared (MIR), visible and near-infrared (VNIR), and Laser-induced breakdown spectrometry (LIBS) spectra were also collected to study vibrational features and elemental emission properties. All these spectral data are valuable for the mixed-cation sulfate detections by those payloads with similar spectroscopic technologies empolyed on Mars. We also studied the conversion relationships among five CSDS, providing constraints for their origins in sedimentary (e.g., calcium sulfate veins) and volcanic environments on Mars.

First-Principles Calculations of the Structural, Electronic, Optical, and Mechanical Properties of 21 Pyrophosphate Crystals

Pyrophosphate crystals have a wide array of applications in industrial and biomedical fields. However, fundamental understanding of their electronic structure, optical, and mechanical properties is still scattered and incomplete. In the present research, we report a comprehensive theoretical investigation of 21 pyrophosphates A2M (H2P2O7)2•2H2O with either triclinic or orthorhombic crystal structure. The molecule H2P2O7 is the dominant molecular unit, whereas A = (K, Rb, NH4, Tl), M = (Zn, Cu, Mg, Ni, Co, Mn), and H2O stand for the cation elements, transition metals, and the water molecules, respectively. The electronic structure, interatomic bonding, partial charge distribution, optical properties, and mechanical properties are investigated by first-principles calculations based on density functional theory (DFT). Most of these 21 crystals are theoretically investigated for the first time. The calculated results show a complex interplay between A, M, H2P2O7, and H2O, resulting in either metallic, half-metallic, or semi-conducting characteristics. The novel concept of total bond order density (TBOD) is used as a single quantum mechanical metric to characterize the internal cohesion of these crystals to correlate with the calculated properties, especially the mechanical properties. This work provides a large database for pyrophosphate crystals and a road map for potential applications of a wider variety of phosphates.

Persona of Transition Metal Ions in Solids: A Statistical Learning on Local Structures of Transition Metal Oxides.

The local structure of a transition metal (TM) ion is a function of cation elements and valence states. More than that, in this work, by employing a trove of first‐principles data of TM oxides, the local structures of TM cations are statistically analyzed to extract detailed information about cation site preference, bond length, site structural distortion, and cation magnetization. It is found that cation radius alone poorly describes the local structure of a transition metal oxide, while the statistics of coordination number as well as the TM—O bond length distribution, especially that of the 3d TMs, can provide comprehensive knowledge for understanding the behavior of TM elements. Based on these statistics, the interplay of site distortion due to the Jahn–Teller effect, cation site similarity, and a new set of ionic radii are all obtained to chart the “persona” of transition metal ions in solids.

Density Functional Theory Study on the Influence of Cation and Anion Elements Doping on the Surface of Ti3C2 on the Adsorption Performance of Formaldehyde

Based on the generalized gradient approximation of density functional theory, the geometric structure and electronic properties of the intrinsic Ti3C2 and Cu-, Pt-, Co-, Si-, F-, Cl- or Br-doped Ti3C2 are optimized, and the adsorption process of HCHO on the surface of the intrinsic Ti3C2 and doped Ti3C2 is calculated. The effects of adsorption energy, stability, DOS and doping on bond length were discussed. The results show that the adsorption energy of the intrinsic Ti3C2 crystal plane at the top site is the strongest, at −7.58 eV. The optimal adsorption sites of HCHO on various doping systems are Cu-Top, Pt-Top, Co-Top, Si-Hollow, Cl-Hollow, F-Bridge and Br-Hollow, respectively. Among the doped elements, anion (F, Cl, Br) doping at each adsorption site generally reduces the formaldehyde adsorption activity of the substrate; cationic doping (Cu, Pt, Co, Si) enhances the adsorption activity of the substrate for formaldehyde at most of the adsorption sites, indicating that the modification effect of anions on Ti3C2 is not as good as that of cations. The adsorption capacity of Si-doped Ti3C2 for formaldehyde was significantly improved. Compared with the intrinsic Ti3C2 crystal plane at the same adsorption site, the adsorption activity of HCHO was improved, and the highest adsorption energy was −8.09 eV.

Biodegradation and effects of EDDS and NTA on Zn in soil solutions during phytoextraction by alfalfa in soils with three Zn levels

In chelator-enhanced Zn phytoremediation studies, it is crucial to understand how the degradable chelators and the competition from other ions influence the concentration of Zn in soil solutions. This study investigated the biodegradability of two chelators (EDDS: Ethylenediamine-N,N′-disuccinic acid, and NTA: Nitrilotriacetic acid) and their effects on the Zn concentration in the soil solution during the growth of alfalfa (Medicago Sativa L.). The chelators were added at four doses (0, 0.5, 2 and 5 mmol kg−1) in soils with varying Zn levels (189, 265 and 1496 mg kg−1). The results showed that the lag phase before EDDS and NTA biodegradation varied from 0 to 7 days in the three soils. EDDS and NTA were completely decomposed within the assessed 57 days regardless of the applied dosage, with a half-life of 1.3–3.0 days in highly Zn-contaminated soil and 4.2–10.8 days in the two other soils. In soil solutions, the change in solubilized Zn was in line with EDDS and NTA degradation kinetics. Cu, Al, Fe and Mn were the main metal ions that competed against Zn for chelation. Besides, Ni competed with Zn in the whole process. Ca did not compete effectively in the three soils, while Mg was a competitor only at the initial stage. Our results show the importance of considering both the biodegradation rate and the competition between the target cation and other elements present in the soil when using chelators to enhance phytoremediation. A 30-day explorative incubation experiment is recommended to evaluate the appropriate application time of chelators and the target Zn exposure time for plants during phytoremediation.

Resorption Efficiency of Four Cations in Different Tree Species in a Subtropical Common Garden

High rainfall in subtropical regions can leach cation elements from ecosystems, which may limit plant growth. Plants often develop efficient resorption patterns to recycle elements, but there is relatively little available information on this topic. In February 2012, a common garden was established in a subtropical forest by planting dominant trees from the area. Green and senescent leaves were sampled from 11 tree species. The concentrations of potassium (K), calcium (Ca), sodium (Na) and magnesium (Mg) were determined, and the resorption efficiencies were calculated. The results showed significant K, Na and Mg resorption in most of the investigated tree species, while Ca mainly displayed accumulation. Evergreen coniferous and evergreen broad-leaved trees (such as Cunninghamia lanceolata, Pinus massoniana, Cinnamomum camphora, and Michelia macclurei) exhibited relatively higher resorption efficiencies of K (39.0%–87.5%) and Na (18.3%–50.2%) than deciduous broad-leaved trees. Higher Mg resorption efficiencies (>50%) were detected in Liriodendron chinense, C. lanceolata and P. massoniana than in other trees. Overall, evergreen coniferous and evergreen broad-leaved trees could show higher cation resorption than deciduous broad-leaved trees. K and Mg resorption efficiencies and Ca accumulation decrease with increasing nutrient concentrations in green leaves. Our results emphasize that nutrient resorption patterns largely depend on elements and plant functions, which provides new insights into the nutrient use strategies of subtropical plants and a reference for the selection of suitable tree species in this region.

Discovery of complex oxides via automated experiments and data science

The quest to identify materials with tailored properties is increasingly expanding into high-order composition spaces, with a corresponding combinatorial explosion in the number of candidate materials. A key challenge is to discover regions in composition space where materials have novel properties. Traditional predictive models for material properties are not accurate enough to guide the search. Herein, we use high-throughput measurements of optical properties to identify novel regions in three-cation metal oxide composition spaces by identifying compositions whose optical trends cannot be explained by simple phase mixtures. We screen 376,752 distinct compositions from 108 three-cation oxide systems based on the cation elements Mg, Fe, Co, Ni, Cu, Y, In, Sn, Ce, and Ta. Data models for candidate phase diagrams and three-cation compositions with emergent optical properties guide the discovery of materials with complex phase-dependent properties, as demonstrated by the discovery of a Co-Ta-Sn substitutional alloy oxide with tunable transparency, catalytic activity, and stability in strong acid electrolytes. These results required close coupling of data validation to experiment design to generate a reliable end-to-end high-throughput workflow for accelerating scientific discovery.

Mechanisms of Carrier Density Increase of Ternary Cation-Based Amorphous Oxide Semiconductors for Thin Film Transistor Applications

Amorphous oxide semiconductor (AOS) thin film transistors (TFTs) based on In2O3 have attracted much interest for use as pixel switching elements in next generation active-matrix liquid crystal (AM-LCD) and active-matrix organic light emitting diode (AM-OLED) displays. The high field effect mobility of In2O3-based AOS devices (10–25 cm2/Vsec) offers significant performance improvements over present-day a-Si TFTs (<1 cm2/Vsec) technology. Additional advantages of AOS materials include low temperature processing (RT–300 °C), isotropic wet etch characteristics, and high optical transparency (>85 % in the visible regime) all of which make this material suitable for large area, flexible, and transparent devices on inexpensive polymer substrates.There have been considerable efforts to incorporate AOSs into devices, particularly in current-driven active matrix displays such as organic light emitting diode displays as pixel-driving switching elements. Strategies to enhance amorphous phase stability, reduce bias stress-induced threshold voltage shifts, and suppress channel carrier densities have been studied and successfully applied to the switching TFT application. Third cation elements are often added to binary cation oxide systems to limit the channel carrier generation for TFT channel application. We have recently reported that the addition of Al to InZnO, a typical binary cation material system leads to enhanced amorphous phase stability, carrier suppression capability and higher carrier mobility, up to ~45 cm2/Vs (Hall Effect mobility) and ~20 cm2/Vs (field effect mobility)1. All of these characteristics are expected to be a key enabler for realizing the next generation ultra-high-definition displays.Post-process annealing is widely employed in AOS-based TFT fabrication since annealing has been shown to improve field effect mobility2-3 and channel/metallization contacts4-5 as well as reduce trap density6, which often leads to unstable device performance or unfavorable hysteresis in their transistor characterstics6-7. However, the post-annealing is often accompanied by an increase in channel carrier density that induces an unfavorable increase in the device off-state current and operation voltages2, 8. To date, the origin of the increase in channel carrier density has not been fully understood.The current study aims to identify the origin of an increase in carrier density after low-temperature annealing conducted in air, particularly for a third-cation AOS system of InAlZnO (IAZO). Through work function investigations and bandgap analysis, the carrier density of IAZO is found to be increased by > 104 times compared to that of unannealed IAZO after low temperature annealing at 200 °C in air. Photoelectron spectroscopic studies reveal that the typical intrinsic (vacancy-based native defect) or extrinsic (cation substitution) doping mechanisms are not the primary cause of the channel carrier increase. From high pressure oxidation with much enhanced reactivity of reaction gases, it is identified that the equilibrium carrier density of IAZO is much higher than those used in typical TFT channel application. The low channel carrier density tends to increase and reach the higher equilibrium carrier density in the absence of kinetic constraints. The combinatorial investigations presented herein help understand the origin of unintentional increase in channel carrier density in amorphous oxides and its effect on the operation of TFTs.The authors gratefully acknowledge the financial supports of the U.S. NSF Award No. ECCS-1931088; the Purdue Research Foundation (Grant No. 60000029); and the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 20011028) by KRISS.References Reed et al. Journal of Materials Chemistry C 2020, 8 (39), 13798-13810.Nomura et al. Applied Physics Letters 2009, 95 (1), 013502.Lee et al. Thin Solid Films 2012, 520 (10), 3764-3768.Shimura et al. Thin Solid Films 2008, 516 (17), 5899-5902.Lee et al. Journal of Applied Physics 2011, 109 (6), 063702.Ide et al. physica status solidi (a) 2019, 216 (5), 1800372.Liu et al. Journal of the American Chemical Society 2010, 132 (34), 11934-11942.Lee et al. Applied Physics Letters 2014, 104 (25), 252103.

Utilization of extracellular polymeric substances (EPS) immobilized in epoxy polymer as double ion exchanger biosorbent for removal of chromium from aqueous solution

Cation and industrial pollutant anions are removed from wastewater using organic cation and anion exchange resin. "Extracellular Polymeric Substance" (EPS) from bacterial extraction can accumulate cation and anion elements through biosorption by adsorption mechanism, ion exchange, formation of complex compounds and hydrogen bonds. EPS can be used as an biosorbent and ion exchange bioresin replacing organic resins, because EPS contains organic functional groups that are negatively charged (RCOOH, ROPO3H, ROPO3Na, ROSO3H, ROSO3Na, etc.) cation absorbers and positively charged (ROH, RCNH2HCOOH, etc.) anion absorber. EPS consists of 40-95% polysaccharide compounds, protein 1-60%, nucleic acids 1-10%, lipids 1-10% and the remaining amino acid polymers and other compounds. The tannery industry produces trivalent (Cr+3) chromium pollutants at levels of 15.2 ppm and hexavalent (CrO4-2 or Cr2O7-2) levels of 0.77 ppm which exceeds the standard quality for a total Cr of 0.6 ppm. Cr pollutants are very dangerous for human health. Research had been done on the use of immobilized EPS bioresin in epoxy polymers for chromium binding. EPS was extracted from bacterial activated sludge by centrifugation at 9000 rpm for 20 minutes at 4°C, the filtrate was EPS. The analysis showed EPS content were 16% fat, 12% carbohydrate, and 16% protein. The functional group analysis results with infrared ray spectroscopy (FTIR) showed EPS containing chemical bonds such as -CH, -OH, -NH, and -C=O which proved that EPS extraction contained RCOOH, ROH, and RCNH2HCOOH functional components which were exchanging components cations and anions. Epoxy polymers were prepared by mixing bisphenol A monomers and 1: 1 ratio epichlorohydrin. Immobilized EPS double ion exchange biorecin in epoxy polymers was prepared by mixing 200 mg EPS and 1800 mg epoxy. The binding of chromium ions in the resin was carried out by recirculating the chromium solution through a burette column filled with 2 rams of bioresin at pH 5, 6 and 7. The optimum results gave chromium ion absorption efficiency of 89.20% at pH 5. Column operations could be optimized by varied the amount of bioresin used.

Co-Solvent Controllable Engineering of MA0.5FA0.5Pb0.8Sn0.2I3 Lead–Tin Mixed Perovskites for Inverted Perovskite Solar Cells with Improved Stability

Use of a lead–tin mixed perovskite is generally considered an effective method to broaden the absorption wavelength of perovskite thin films. However, the preparation of lead–tin mixed perovskites is a major challenge due to the multivalent state of tin and stability in the atmosphere. This study attempted to replace the organic cation and metal elements of perovskites with a relatively thermal stable formamidinium (FA+) and a more environmentally friendly tin element. MA0.5FA0.5Pb0.8Sn0.2I3 lead–tin mixed perovskite thin films were prepared with the one-step spin-coating method. By adjusting the dimethylformamide (DMF):dimethyl sulfoxide (DMSO) concentration ratio of the lead–tin mixed perovskite precursor solution, the surface morphologies, crystallinity, and light-absorbing properties of the films were changed during synthesis to optimize the lead–tin mixed perovskite films as a light-absorbing layer of the inverted perovskite solar cells. The quality of the prepared lead–tin mixed perovskite film was the highest when the ratio of DMF:DMSO = 1:4. The power-conversion efficiency of the perovskite solar cell prepared with the film was 8.05%.

Random Forest Models for Accurate Identification of Coordination Environments from X-Ray Absorption Near-Edge Structure

SummaryAnalyzing coordination environments using X-ray absorption spectroscopy has broad applications in solid-state physics and material chemistry. Here, we show that random forest models trained on 190,000 K-edge X-ray absorption near-edge structure (XANES) spectra can identify the main atomic coordination environment with a high accuracy of 85.4% and all associated coordination environments with a high Jaccard score of 81.8% for 33 cation elements in oxides, significantly outperforming other machine-learning models. In a departure from prior works, the coordination environment is described as a distribution over 25 distinct coordination motifs with coordination numbers ranging from 1 to 12. More importantly, we show that the random forest models can be used to predict coordination environments from experimental K-edge XANES with minimal loss in accuracy. A drop-variable feature importance analysis highlights the key roles that the pre-edge and main-peak regions play in coordination environment identification.

Incongruent pulsed laser deposition strategy for thin film growth of Ca3Co4O9 thermoelectric compound

Abstract Pulsed laser deposition (PLD) is commonly used to grow thin film materials with complex stoichiometry and crystal structures, since it achieves a congruent transfer of the target cation elements to the substrate. Although the incongruent PLDs were previously observed via regulating the plasma/background interaction regimes, the incongruent PLDs were seldom investigated and applied practically for the thin film depositions. Herein, we demonstrate the incongruent pulsed laser deposition of Ca3Co4O9 thermoelectric thin films, via regulating the target compositions and the oxygen background pressures to preferential scattering the plasma cation compositions. To compare the deposition properties via incongruent and congruent thin film growth, we systematically investigate the crystal structures, surface morphologies, elemental distributions and thermoelectric transportation behaviors for Ca3Co4O9 thin films grown at various target compositions and background pressure ranges. A stoichiometric Ca3Co4O9 thin film composition is achievable via designing an incongruent PLD strategy, in which case the Ca/Co ratios in the targets are enlarged actively while the PLDs are performed at a pressure range of 100 Pa to further preferential scatter of the lighter Ca compared to Co. Nevertheless, the incongruently grown thin films exhibit lower thermoelectric performances, compared to the one at a similar composition grown via the congruent PLD strategy. This result may associate to the localized composition inhomogeneity in the Ca3Co4O9 grown incongruently, and their electronical resistivities are largely elevated by the resultant impurities that are hardly detectable by X-ray diffractions. The present work reveals the complexity in deposition mechanism and kinetics when performing incongruent PLDs, in particular, for growing multiple elemental thin film materials.

A Li2CuPS4 superionic conductor: a new sulfide-based solid-state electrolyte

The small electronegativity difference between the anion element and non-lithium cation elements makes fast tetrahedral Li ion diffusion in our DFT predicted Li2CuPS4 solid-state electrolyte material.

Further insight into the role of Ca2+ in broiler pale, soft and exudative-like (PSE) meat through the analysis of moisture by TGA and strong cation elements by ICP-OES.

This study evaluated moisture content of broiler breast PSE meat by thermal gravimetric analysis and strong cation elements by inductively coupled plasma optical emission spectrometry. The weight changes were monitored within the temperature interval 9-750°C and the most severe changes were observed at 9-160°C (1A). This remarkable transition was attributed to water loss of about 64.74% in normal samples while PSE samples lost about 61.16%. There was, therefore, approximately 4.0% lower moisture in PSE meat samples in relation to normal meat. The analysis of cation elements showed significant differences (p < 0.05), with normal samples having 13.0% higher ∑[Ca2+] + [Mg2+] + [Na+]+[K+] than PSE meat samples while [Ca2+] in PSE meat was 10.81% higher than in the normal counterparts. We provided further evidence of the role of Ca2+ excess within the muscle sarcomere during the onset of PSE meat.

Origin of polymorphism of the two-dimensional group-IV monochalcogenides

Unlike other two-dimensional (2D) isovalent materials, the 2D group IV monochalcogenides, $MX$ ($M\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}\mathrm{Si}$, Ge, Sn, and Pb; $X\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}\mathrm{S}$, Se, and Te), are found to be either in a black phosphorene-derived distorted NaCl-type ($d$-NaCl) structure or a recently predicted $Pma2$ structure. Both $M$ and $X$ atoms in the $d$-NaCl structure are threefold coordinated, whereas $M$ and $X$ in the $Pma2$ structure are fourfold and twofold coordinated, respectively. Using first-principles total energy and electronic structure calculations and a global structural search technique, we systematically investigated the mechanism underlying the polymorphism of the 2D group-IV monochalcogenides. Our analysis show that the relative stability of the two distinct crystallographic phases depends on the strength of the $M\ensuremath{-}M$ covalent bond and the electronegativity difference between the constituent elements $M$ and $X$. For small cations, the covalency plays more important role, whereas for large cations the Coulomb interaction becomes more dominant. Therefore, the $\mathrm{Si}X$ and $\mathrm{Ge}X$ compounds assume the $Pma2$ structure, whereas the $MX$ compounds with heavy cation elements ($M\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}\mathrm{Sn}$ and Pb) tend to adopt the $d$-NaCl structure.

Oxygen Electrocatalysis on Cobalt-Based Layered Perovskite Oxychlorides in Alkaline Media

Introduction There has been increasing attention to electrochemical energy conversion devices using oxygen electrodes in alkaline media such as fuel cells, metal−air rechargeable batteries, and water-splitting devices. Because of the sluggish kinetics of the oxygen electrode reactions, many researchers have been exploring cost-effective materials which can catalyze both/either oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER). Among various kinds of catalysts, a family of perovskite-type compounds have been extensively studied because of its structural and compositional flexibility. In order to enhance the catalytic activity of perovskites, researches based on the choice of cation elements and their compositions has been extensively conducted.1 On the other hand, those based on the choice of anion elements and their compositions has been rarely conducted. These days, some research groups report that mixed-anion catalysts exhibit ORR and/or OER activities,2,3 suggesting that “anion blending” can be a great tool for enhancing catalytic activity of perovskites. Therefore, the present work focuses on the measurement of ORR and OER activities for mixed-anion perovskites. Herein we used Sr2CoO3Cl and its related materials.4 Experimental Sr2CoO3Cl and Sr3Co2O5Cl2 were synthesized by a solid-state method. Sr2Co2O5 precursor was firstly prepared by heating a stoichiometric mixture of SrCO3 and Co3O4 at 1273 K in air followed by quenching in liquid N2. Next, stoichiometric amounts of Sr2Co2O5, SrCO3, and SrCl2·6H2O were mixed and heated at 1123 K in air. For benchmarking catalysts, LaSrCoO4, which has the same crystal structure and valence state of cobalt ion, LaCoO3, which is a well-known single-perovskite catalyst with the same valence state of cobalt ion, and Ba0.5Sr0.5Co0.8Fe0.2O3 -d (BSCF), which is known as a highly-active OER electrocatalyst, were used. ORR and OER activities of the samples were carried out by using three-electrode electrochemical cell with rotating disk electrode (RDE) setup. Composite electrodes consisting of perovskites, Vulcan XC-72 (Cabot), and AS-4 (Tokuyama) were formed on a glassy carbon RDE and were used as the working electrode. Pt wire, reversible hydrogen electrode (RHE), and 1.0 mol dm-3 KOH solution were used as the counter electrode, the reference electrode, and the electrolyte, respectively. Results and discussions From scanning electron microscope-energy dispersive X-ray spectroscopy, the oxychlorides had a particle size of 1-10 μm with almost ideal atomic concentrations. X-ray diffraction patterns of the oxychlorides were almost identical to those in ICSD database. While the ORR activity of LaSrCoO4 was negligible, that of the oxychlorides was as high as that of LaCoO3, indicating that the mixing of oxide and chloride ions was effective to add the ORR activity. Fig. 1 shows OER polarization curves of perovskite catalysts. Surprisingly, the OER activity of Sr2CoO3Cl was as high as that of BSCF, proving that “anion blending” is a powerful tool to enhance the OER activity. Roles of chloride ion in improving ORR and OER activities will be discussed in the conference. Fig. 1. OER polarization curves of (solid line) Sr2CoO3Cl, (dashed line) LaSrCoO4, and (dotted line) Ba0.5Sr0.5Co0.8Fe0.2O3 -d in 1 mol dm-3 KOH solution.

Identification of Cation Elements in PM10 Concentration in Industrial Area of Penang

This study aims to investigate the concentrations of particulate matter with an aerodynamic diameter of less than 10 micron (PM10) and their associated cation elements in PM10. The sample of PM10 was collected at Royal Malaysian Customs Department (N5° 22’ 012”; E100° 23’589”) located in Perai Industrial Area, Penang, from June to September 2015. The sampling was carried out during the southwest monsoon and a total of 12 samples were collected using a low volume sampler (LVS). Results suggested that there are five elements that are commonly identified from PM sampled which are ammonium, sodium, potassium, calcium and magnesium. The concentrations of the cation from all four months in the industrial area shows the order of NH4 + &gt; Ca+ &gt; K+ &gt; Mg2+ &gt; Na+ . The lowest and highest concentrations calculated both were ammonium (0.012 ?g/m3) in July and (0.873 ?g/m3) September, respectively.

Cation Mixing Properties toward Co Diffusion at the LiCoO2 Cathode/Sulfide Electrolyte Interface in a Solid-State Battery.

All-solid-state Li-ion batteries (ASS-LIBs) are expected to be the next-generation battery, however, their large interfacial resistance hinders their widespread application. To understand and resolve the possible causes of this resistance, we examined mutual diffusion properties of the cation elements at LiCoO2 (LCO) cathode/β-Li3PS4 (LPS) solid electrolyte interface as a representative system as well as the effect of a LiNbO3 buffer layer by first-principles calculations. Evaluating energies of exchanging ions between the cathode and the electrolyte, we found that the mixing of Co and P is energetically preferable to the unmixed states at the LCO/LPS interface. We also demonstrated that the interposition of the buffer layer suppresses such mixing because the exchange of Co and Nb is energetically unfavorable. Detailed analyses of the defect levels and the exchange energies by using the individual bulk crystals as well as the interfaces suggest that the lower interfacial states in the energy gap can make a major contribution to the stabilization of the Co ↔ P exchange, although the anion bonding preference of Co and P as well as the electrostatic interactions may have effects as well. Finally, the Co ↔ P exchanges induce interfacial Li sites with low chemical potentials, which enhance the growth of the Li depletion layer. These atomistic understandings can be meaningful for the development of ASS-LIBs with smaller interfacial resistances.