Showing papers on "Antimony published in 2014"

Monodisperse antimony nanocrystals for high-rate Li-ion and Na-ion battery anodes: nano versus bulk.

Abstract: We report colloidal synthesis of antimony (Sb) nanocrystals with mean size tunable in the 10–20 nm range and with narrow size distributions of 7–11%. In comparison to microcrystalline Sb, 10 and 20 nm Sb nanocrystals exhibit enhanced rate-capability and higher cycling stability as anode materials in rechargeable Li-ion and Na-ion batteries. All three particle sizes of Sb possess high and similar Li-ion and Na-ion charge storage capacities of 580–640 mAh g–1 at moderate charging/discharging current densities of 0.5–1C (1C-rate is 660 mA g–1). At all C-rates (0.5–20C, e.g. current densities of 0.33–13.2 Ag1–), capacities of 20 nm Sb particles are systematically better than for both 10 nm and bulk Sb. At 20C-rates, retention of charge storage capacities by 10 and 20 nm Sb nanocrystals can reach 78–85% of the low-rate value, indicating that rate capability of Sb nanostructures can be comparable to the best Li-ion intercalation anodes and is so far unprecedented for Na-ion storage.

Hydrothermal-synthesized SrTiO3 photocatalyst codoped with rhodium and antimony with visible-light response for sacrificial H2 and O2 evolution and application to overall water splitting

Abstract: The codoping effect of antimony on the photocatalytic activity of visible-light-driven SrTiO 3 doped with rhodium (SrTiO 3 :Rh) was investigated. SrTiO 3 doped with rhodium and antimony (SrTiO 3 :Rh/Sb) prepared by a hydrothermal method was found to be active for photocatalytic H 2 evolution from an aqueous methanol solution and O 2 evolution from an aqueous silver nitrate solution under visible light irradiation, although SrTiO 3 doped with rhodium and no antimony was active only for the H 2 evolution. Photocatalytic activities of SrTiO 3 :Rh/Sb were strongly dependent on the ratio of codopant to dopant (Sb/Rh). Diffuse reflection spectroscopy (DRS), electron spin resonance (ESR), Raman, and action spectrum analyses revealed the contribution of rhodium and antimony to visible-light response of SrTiO 3 :Rh/Sb. Unstable and reversible Rh 3+ ions in oxidation state were the superior species for the H 2 evolution. On the other hand, Rh 3+ ions stabilized by codoping of antimony without the formation of Rh 4+ ions and oxygen defects which would work as undesirable recombination sites between photogenerated electrons and holes played an important role in the O 2 evolution. Moreover, when an IrO X cocatalyst was loaded on the surface of the SrTiO 3 :Rh/Sb photocatalyst, the photocatalytic activity of the O 2 evolution drastically increased. The apparent quantum yield for the H 2 evolution over Pt(0.3 wt%)/SrTiO 3 :Rh(1%)/Sb(1%) and the O 2 evolution over IrO X (3.0 wt%)/SrTiO 3 :Rh(1%)/Sb(1%) at 420 nm were 0.8% and 4.5%, respectively. The Z -scheme system composed of Ru(1.0 wt%)/SrTiO 3 :Rh(2%) as a H 2 -evolving photocatalyst, IrO X (3.0 wt%)/SrTiO 3 :Rh(1%)/Sb(1%) as an O 2 -evolving photocatalyst, and an Fe 3+ /Fe 2+ redox couple as an electron mediator showed photocatalytic activity for overall water splitting under visible light irradiation.

Mono-, few-, and multiple layers of copper antimony sulfide (CuSbS2): a ternary layered sulfide.

Abstract: Layered materials with controlled thickness down to monolayer are being intensively investigated for unraveling and harnessing their dimension-dependent properties. Copper antimony sulfide (CuSbS2) is a ternary layered semiconductor material that has been considered as an absorber material in thin film solar cells due to its optimal band gap (∼1.5 eV) with high absorption coefficient of over >104 cm–1. We have for the first time developed solution-based approaches for the synthesis of mono-, few-, and multiple layers of CuSbS2. These include a colloidal bottom-up approach for the synthesis of CuSbS2 nanoplates with thicknesses from six layers to several layers, and a hybrid bottom-up-top-down approach for the formation of CuSbS2 mesobelts. The latter can be exfoliated by Li-ion intercalation and sonication to obtain layers down to monolayer thickness. Time-dependent TEM studies provide important insights into the growth mechanism of mesobelts. At the initial stage the nanoplates grow laterally to form nan...

Dissimilatory Antimonate Reduction and Production of Antimony Trioxide Microcrystals by a Novel Microorganism

Abstract: Antimony (Sb) is a metalloid that has been exploited by humans since the beginning of modern civilization. The importance of Sb to such diverse industries as nanotechnology and health is underscored by the fact that it is currently the ninth-most mined metal worldwide. Although its toxicity mirrors that of its Group 15 neighbor arsenic, its environmental chemistry is very different, and, unlike arsenic, relatively little is known about the fate and transport of Sb, especially with regard to biologically mediated redox reactions. To further our understanding of the interactions between microorganisms and Sb, we have isolated a bacterium that is capable of using antimonate [Sb(V)] as a terminal electron acceptor for anaerobic respiration, resulting in the precipitation of antimonite [Sb(III)] as microcrystals of antimony trioxide. The bacterium, designated strain MLFW-2, is a sporulating member of a deeply branching lineage within the order Bacillales (phylum Firmicutes). This report provides the first unequivocal evidence that a bacterium is capable of conserving energy for growth and reproduction from the reduction of antimonate. Moreover, microbiological antimonate reduction may serve as a novel route for the production of antimony trioxide microcrystals of commercial significance to the nanotechnology industry.

Investigation of Influencing Factors and Mechanism of Antimony and Arsenic Removal by Electrocoagulation Using Fe–Al Electrodes

Abstract: Exposure to antimony (Sb) and arsenic (As) through contaminated surface water poses a great threat to human health. In this work, Sb and As were removed simultaneously by electrocoagulation (EC) using Fe–Al electrodes. The effects of current density, pH, initial concentration, aeration intensity, and anions were investigated. A higher current density achieved better removal performance. The optimum pH range was 5.0–7.0. Sb and As removals were slower at higher initial concentrations. Preoxidation was beneficial to As removal, whereas anoxic conditions were more favorable for Sb removal. Nitrate and sulfate had little influence on the performance of the EC process, but significant inhibition was observed in phosphate-rich solutions. Scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis demonstrated that adsorption onto iron and aluminum hydroxides/oxyhydroxides was the predominant mechanism involved in Sb and As remova...

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Abstract: diffusivity of Ca in Sb. The cell was successfully cycled with high coulombic efficiency (∼100%) and small fade rate (<0.01%

Kinetics and mechanism of photopromoted oxidative dissolution of antimony trioxide.

Abstract: Light (sunlight, ultraviolet, simulated sunlight) irradiation was used to initiate the dissolution of antimony trioxide (Sb2O3). Dissolution rate of Sb2O3 was accelerated and dissolved trivalent antimony (Sb(III)) was oxidized in the irradiation of light. The photopromoted oxidative dissolution mechanism of Sb2O3 was studied through experiments investigating the effects of pH, free radicals scavengers, dissolved oxygen removal and Sb2O3 dosage on the release rate of antimony from Sb2O3 under simulated sunlight irradiation. The key oxidative components were hydroxyl free radicals, photogenerated holes and superoxide free radicals; their contribution ratios were roughly estimated. In addition, a conceptual model of the photocatalytic oxidation dissolution of Sb2O3 was proposed. The overall pH-dependent dissolution rate of Sb2O3 and the oxidation of Sb(III) under light irradiation were expressed by r = 0.08 ·[OH(-)](0.63) and rox = 0.10 ·[OH(-)](0.79). The present study on the mechanism of the photo-oxidation dissolution of Sb2O3 could help clarify the geochemical cycle and fate of Sb in the environment.

Enhancing the Thermoelectric Properties of Germanium Antimony Tellurides by Substitution with Selenium in Compounds GenSb2(Te1–xSex)n+3 (0 ≤ x ≤ 0.5; n ≥ 7)

Abstract: Quenched pseudocubic germanium antimony tellurides (GST compounds) exhibit promising thermoelectric properties. These are related to the nanostructures which can be influenced by varying the composition and the thermal treatment. The substitution of Te by Se in bulk samples of GenSb2Ten+3 with high thermoelectric figures of merit (ZT) is possible over a wide compositional range. This results in solid solution series GenSb2(Te1–xSex)n+3 with 0 < x < 0.75 for n ≥ 7. Se substitution reduces the average lateral extension of the defect layers in quenched samples. This is a consequence of the reduced mobility during the quenching process due to the lower cubic to trigonal phase transition temperatures of Se-substituted samples. Most pronounced for n = 7, Se doping increases the transition temperatures between the nanostructured (pseudo)cubic modification of quenched samples and their layered trigonal phase. This increases the temperature ranges in which the materials can be employed without altering their nanos...

Isolation and Characterization of Antimony-Reducing Bacteria from Sediments Collected in the Vicinity of an Antimony Factory

Abstract: To date, there is very little information available on the oxidation and reduction of antimony by bacteria. An antimonate-respiring bacterium was isolated from sediment samples collected in the vicinity of an antimony oxide-producing factory in Korea. This bacterium was isolated by application of the Hungate standard anaerobic culture technique. Temporarily named strain JUK-1, it was found to be a rod-shaped bacterium and occurred individually or in pairs. Antimonate (pentavalent antimony) was reduced to antimonite (trivalent antimony) in the presence of JUK-1 in an anoxic minimal medium containing 5 mM antimonate and 10 mM acetate. The organism grew optimally at an initial pH of 7.7 and a temperature of 30°C. A part of the antimonite which was produced in medium precipitated as a bio-mineral containing approximately 50.0% antimony, 33.5% oxygen, 12.7% carbon, 2.0% sodium and 1.9% magnesium by weight. Based on the phylogenetics of 16S rRNA gene sequence and DNA G+C content, JUK-1 appears to be a new strai...

Sb2O3 Nanowires as Anode Material for Sodium-Ion Battery

Abstract: The anodic properties of antimony trioxide (Sb2O3) nanowires were investigated as electrode material for sodium-ion battery. Sb2O3 nanowires were prepared via a mild-condition, solvothermal route based on the hydrolysis of antimony trichloride (SbCl3) in alcohol aqueous solution. The uniform morphology and crystal phases of Sb2O3 nanowires are confirmed by scanning electronic microscopy, transmission electronic microscopy, and X-ray diffraction. The electrochemical performance of Sb2O3 nanowire anodes was studied and the material exhibits a high reversible capacity of 230 mAh/g which is attributed to the reversible complex conversion–alloying reactions between antimony trioxide and sodium.

Transparent Conducting Aerogels of Antimony-Doped Tin Oxide

Abstract: Bulk antimony-doped tin oxide aerogels are prepared by epoxide-initiated sol–gel processing. Tin and antimony precursors are dissolved in ethanol and water, respectively, and propylene oxide is added to cause rapid gelation of the sol, which is then dried supercritically. The Sb:Sn precursor mole ratio is varied from 0 to 30% to optimize the material conductivity and absorbance. The materials are characterized by electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), nitrogen physisorption analysis, a four-point probe resistivity measurement, and UV–vis diffuse reflectance spectroscopy. The samples possess morphology typical of aerogels without significant change with the amount of doping. Calcination at 450 °C produces a cassiterite crystal structure in all aerogel samples. Introduction of Sb at 15% in the precursor (7.6% Sb by XPS) yields a resistivity more than 3 orders of magnitude lower than an undoped SnO2 aerogel. Calcination at 800 °C redu...

Removal of Sb(III) and Sb(V) from Aqueous Solutions Using nZVI

Abstract: Nanoscale zero-valent iron (nZVI) was synthesized and used for the removal of Sb(III) and Sb(V) from aqueous solutions. Results showed that more than 90 % of antimony would be removed in 15 min and that all of antimony could be removed with appropriate nZVI dosage in 90 min. The influence of pH value and possible impurities was investigated. The pH of 4 was found as the optimum pH. Discussion and speculation about the mechanism were presented according to X-ray photoelectron spectroscopy and transmission electron microscopy data. A sheet-like structure was observed after a 90-min reaction, and antimony was detected on the surface by energy-dispersive X-ray spectroscopy. Both Sb(III) and Sb(V) partially reduced in the process. The presence of humic acid transformed the morphology of nZVI but barely influenced the removal efficiency. Competing ions showed diverse influence between Sb(III) and Sb(V). The overall results indicated that nZVI was an efficient and suitable material for the removal of antimony.

Metal‐Free Stabilization of Monomeric Antimony(I): A Carbene‐Supported Stibinidene

Abstract: A diamidocarbene was coordinated to an antimony(III) dichloride Lewis acid. Subsequent reduction with magnesium gave a monomeric, formally antimony(I) fragment that is supported by the diamidocarbene. Spectroscopic, crystallographic, and computational analyses demonstrated that the carbene ligand engages the antimony(I) center in π-backbonding resulting in a short (2.068(7) A) SbC interaction that is comparable to those observed in known stibaalkenes.

Copper and antimony isotopic analysis via multi-collector ICP-mass spectrometry for provenancing ancient glass

Abstract: Variations in the isotopic composition of Cu and Sb as determined using multi-collector ICP-mass spectrometry (MC-ICPMS) have been investigated as a proxy for provenancing ancient glass. Cu and Sb were added during the manufacturing of ancient (pre-Roman and Roman) glass to obtain colour and opacity. In previous work, the analytical methodology for sample digestion and isolation of Sb preceding isotopic analysis via multi-collector ICP-MS was developed. Although applications of Cu isotopic analysis can be found in the literature, this approach has not been used for provenancing glass raw materials yet. Therefore, the protocols for digestion and Cu isolation were optimized and validated, relying on the use of both an in-house multi-elemental standard and NIST SRM 610 glass reference material. The methods for Sb and Cu isotopic analysis were subsequently applied to a series of late Bronze Age Mesopotamian–Egyptian to Hellenistic–Roman glasses. Results obtained show that the isotopic composition of Cu, expressed as δ65Cu, varies from −1.9 to −0.2‰, thus covering a range of approximately 2‰. Unfortunately, the use of Cu isotope ratios to characterize raw materials used in glass manufacturing is complicated by the fact that Cu ores from within a single deposit can exhibit a similar range in δ65Cu values, certainly for co-existing Cu sulfides and oxides. Sb in stibnite ore, on the other hand, only shows a variance in isotopic composition of ∼10 e units (or 0.1‰), but Sb isotopic analysis offers more potential to pinpoint the location of an antimony source used in antiquity.

Food crop accumulation and bioavailability assessment for antimony (Sb) compared with arsenic (As) in contaminated soils

Abstract: Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was <10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75 ± 0.52 μg L–1) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was <7 % for total As and <3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.

Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

Abstract: Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 A . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.