Showing papers on "Antimony published in 2017"

Unlocking the Electrocatalytic Activity of Antimony for CO2 Reduction by Two-Dimensional Engineering of the Bulk Material.

Abstract: Two-dimensional (2D) materials are known to be useful in catalysis. Engineering 3D bulk materials into the 2D form can enhance the exposure of the active edge sites, which are believed to be the origin of the high catalytic activity. Reported herein is the production of 2D "few-layer" antimony (Sb) nanosheets by cathodic exfoliation. Application of this 2D engineering method turns Sb, an inactive material for CO2 reduction in its bulk form, into an active 2D electrocatalyst for reduction of CO2 to formate with high efficiency. The high activity is attributed to the exposure of a large number of catalytically active edge sites. Moreover, this cathodic exfoliation process can be coupled with the anodic exfoliation of graphite in a single-compartment cell for in situ production of a few-layer Sb nanosheets and graphene composite. The observed increased activity of this composite is attributed to the strong electronic interaction between graphene and Sb.

Solution-processable antimony-based light-absorbing materials beyond lead halide perovskites

Abstract: Organic–inorganic lead halide perovskites have recently emerged as highly competitive light absorbing materials for low cost solution-processable photovoltaic devices. With the high efficiency already achieved, removing the toxicity, i.e., lead-free and stability are the key obstacles for perovskite solar cells. Here, we report the synthesis of an antimony (Sb)-based hybrid material having the composition of A3Sb2I9 [A = CH3NH3 (MA), Cs] and an investigation of its potential photovoltaic applications. Sb-based perovskite-like materials exhibited attractive absorbance properties, with the band gaps of MA3Sb2I9 and Cs3Sb2I9 measured to be 1.95 and 2.0 eV, respectively. X-ray photoelectron spectroscopy confirmed the formation of stoichiometric perovskites from appropriate precursor molar ratios incorporated with hydroiodic acid (HI). Planar hybrid Sb-based solar cells exhibited negligible hysteresis and reproducible power output under working conditions. A power conversion efficiency of 2.04% was achieved by the MA3Sb2I9 perovskite-based device—the highest reported to date for a Sb-based perovskite solar cell.

Insights into Antimony Adsorption on {001} TiO2: XAFS and DFT Study

Abstract: Antimony (Sb) contamination poses an emerging environmental risk, whereas its removal remains a contemporary challenge due to the lack of knowledge in its surface chemistry and efficient adsorbent. In this study, self-assembly {001} TiO2 was examined for its effectiveness in Sb removal, and the molecular level surface chemistry was studied with X-ray absorption spectroscopy and density functional theory calculations. The kinetics results show that Sb adsorption followed the pseudo-second order reaction, and the Langmuir adsorption capacity was 200 mg/g for Sb(III) and 156 mg/g for Sb(V). The PZC of TiO2, which was 6.6 prior to the adsorption experiment, shifted to 4.8 and <0 after adsorption of Sb(III) and Sb(V), respectively, indicating the formation of negatively charged inner-sphere complexes. EXAFS results suggest that Sb(III/V) adsorption exhibited a bidentate binuclear surface complex. The orbital hybridizing of complexes was studied by XANES, molecular orbital theory (MO), and density of states (DO...

Screening of Zirconium-Based Metal–Organic Frameworks for Efficient Simultaneous Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution

Abstract: Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency st...

Efficient Removal of Antimony (III, V) from Contaminated Water by Amino Modification of a Zirconium Metal–Organic Framework with Mechanism Study

Abstract: The adsorption performance of the amino modification of zirconium metal–organic framework (UiO-66(NH2)) for the removal of antimony (Sb) from aqueous solution has been investigated. The influence of equilibrium concentration, solution pH, temperature, and contact time on the Sb adsorption were investigated by the batch method. Compared with original UiO-66, the UiO-66(NH2) adsorption capacity for Sb(III) and Sb(V) increased to 61.8 mg/g and 105.4 mg/g for Sb(III) and Sb(V), although the surface area of UiO-66(NH2) decreased from 486.31 m2/g to 113.46 m2/g. The adsorption equilibrium data of Sb on UiO-66(NH2) fitted well with the Langmuir adsorption model, and the kinetics data fitted well with the second-order adsorption model. Thermodynamic parameters indicated that adsorption processes of Sb were feasible, endothermic, and spontaneous. The adsorption isotherm parameters indicated that the Sb adsorption data fitted well with the Langmuir model. The mean adsorption energy obtained from the Dubinin–Radushk...

Antimony and arsenic behavior during FE(II)-induced transformation of jarosite

Abstract: Jarosite can be an important scavenger for arsenic (As) and antimony (Sb) in acid mine drainage (AMD) and acid sulfate soil (ASS) environments. When subjected to reducing conditions, jarosite may undergo reductive dissolution, thereby releasing As, Sb, and Fe2+ coincident with a rise in pH. These conditions can also trigger the Fe2+-induced transformation of jarosite to more stable Fe(III) minerals, such as goethite. However, the consequences of this transformation process for As and Sb are yet to be methodically examined. We explore the effects of abiotic Fe2+-induced transformation of jarosite on the mobility, speciation, and partitioning of associated As(V) and Sb(V) under anoxic conditions at pH 7. High concentrations of Fe2+ (10 and 20 mM) rapidly (<10 min) transformed jarosite to a green rust intermediary, prior to the subsequent precipitation of goethite within 24 h. In contrast, lower concentrations of Fe2+ (1 and 5 mM) led to the formation of lepidocrocite. As K-edge XANES spectroscopy revealed s...

Synthesis and characterization of 2A-3SHPA decorated ZnS@CdS core–shell heterostructure nanowires as a fluorescence probe for antimony ions detection

Abstract: A fluorescent probe based on CdS/ZnS core/shell heterostructure nanowires decorated with 2-Amino-3-sulfhydrylpropanoic acid (2A-3SHPA) has been designed for the detection of antimony ions at nanomolar levels for the first time. The structural and morphological characterizations indicated that zinc sulfide shell with a zinc blend cubic structure was epitaxially grown along the radial core of the wurtzite hexagonal cadmium sulfide structure with high quality interface via cation exchange mechanism. The optical studies revealed that the developed CdS/ZnS core-shell nanowires have superior intense green luminescence emission at ambient temperature demonstrating efficient charge carriers recombination inside the CdS core. At the optimum conditions, the fluorescence intensity showed a linear regression against the antimony concentration along the range from 1 nM to 1000 nM with detection limit 1.2 × 10−11 mol L−1. The developed fluorescence probe exhibited high photo-stability against temperature up to 60 °C as well as storage time till 2 months. These superior characteristics may enable the developed core-shell nanowires to monitor the traces of antimony ions to evade their dangerous effect on the health such as albuminuria and glycosuria.

Antimony Anchored with Nitrogen-Doping Porous Carbon as a High-Performance Anode Material for Na-Ion Batteries

Abstract: Antimony represents a class of unique functional materials in sodium-ion batteries with high theoretical capacity (660 mA h g–1). The utilization of carbonaceous materials as a buffer layer has been considered an effective approach to alleviate rapid capacity fading. Herein, the antimony/nitrogen-doping porous carbon (Sb/NPC) composite with polyaniline nanosheets as a carbon source has been successfully achieved. In addition, our strategy involves three processes, a tunable organic polyreaction, a thermal annealing process, and a cost-effective reduction reaction. The as-prepared Sb/NPC electrode demonstrates a great reversible capacity of 529.6 mA h g–1 and an outstanding cycling stability with 97.2% capacity retention after 100 cycles at 100 mA g–1. Even at 1600 mA g–1, a superior rate capacity of 357 mA h g–1 can be retained. Those remarkable electrochemical performances can be ascribed to the introduction of a hierarchical porous NPC material to which tiny Sb nanoparticles of about 30 nm were well-wra...

The potential for the treatment of Antimony-containing Wastewater by Iron-based Adsorbents

Abstract: Antimony (Sb) and its compounds are considered as global priority pollutants. Elevated concentrations of antimony in natural and industrial process wastewater are of global concern, particularly given interest in the potential toxicity and harm to the environment from aquatic exposure. Iron-based materials for treatment by adsorption are widely regarded to have potential merit for the removal of trace contaminants from water and especially in the search for efficient and low-cost techniques. In this paper, we review the application of iron-based materials in the sorption treatment of antimony contaminated water. The interaction of Sb is discussed in relation to adsorption performance, influencing factors, mechanism, modelling of adsorption (isotherm, kinetic and thermodynamic models), advantages, drawbacks and the recent achievements in the field. Although iron-based adsorbents show promise, the following three aspects are in need of further study. Firstly, a select number of iron based binary metal oxide adsorbents should be further explored as they show superior performance compared to other systems. Secondly, the possibility of redox reactions and conversion between Sb(III) and Sb(V) during the adsorption process is unclear and requires further investigation. Thirdly, in order to achieve optimized control of preferential adsorption sites and functional groups, the mechanism of antimony removal has to be qualitatively and quantitatively resolved by combining the advantages of advanced characterization techniques such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy (XPS), Atomic force microscope(AFM), X-ray absorption near edge structure(XANES), and other spectroscopic methods. We provide details on the achievements and limitations of each of these stages and point to the need for further research.

One-Pot Synthesis of Antimony-Embedded Silicon Oxycarbide Materials for High-Performance Sodium-Ion Batteries

Abstract: Sodium-ion batteries have recently attracted intensive attention due to their natural abundance and low cost. Antimony is a desirable candidate for an anode material for sodium-ion batteries due to its high theoretical capacity (660 mA h g−1). However, the utilization of alloy-based anodes is still limited by their inherent huge volume changes and sluggish kinetics. The Sb-embedded silicon oxycarbide (SiOC) composites are simply synthesized via a one-pot pyrolysis process at 900 °C without any additives or surfactants, taking advantage of the superior self-dispersion properties of antimony acetate powders in silicone oil. The structural and morphological characterizations confirm that Sb nanoparticles are homogeneously embedded into the amorphous SiOC matrix. The composite materials exhibit an initial desodiation capacity of around 510 mA h g−1 and maintained an excellent capacity retention above 97% after 250 cycles. The rate capability test reveals that the composites deliver capacity greater than 453 mA h g−1, even at the high current density of 20 C rate, owing to the free-carbon domain of SiOC material. The electrochemical and postmortem analyses confirm that the SiOC matrix with a uniform distribution of Sb nanoparticles provides the mechanical strength without degradation in conductive characteristics, suppressing the agglomeration of Sb particles during the electrochemical reaction.

Solid-state nanocrystalline solar cells with an antimony sulfide absorber deposited by an in situ solid–gas reaction

Abstract: An Sb2S3 absorber layer is coated on mesoporous TiO2 films through a sequential deposition method: SbCl3 aqueous solution is first deposited, followed by reaction with H2S gas and further thermal annealing. Under our conditions, the Sb2S3-based solid-state heterojunction solar cells yield efficiencies of up to 6.27% at 100 mW cm−2 AM 1.5 G.

Antimony oxidation and adsorption by in-situ formed biogenic Mn oxide and Fe-Mn oxides.

Abstract: Antimony (Sb), which can be toxic at relatively low concentrations, may co-exist with Mn(II) and/or Fe(II) in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb (III and V) species in the presence of Mn(II) and Mn-oxidizing bacteria, with or without Fe(II). Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides (BMOs), which were formed in-situ via the oxidation of Mn(II) by a Mn-oxidizing bacterium (Pseudomonas sp. QJX-1). Results indicated that Sb(III) ions could be oxidized to Sb(V) ions by BMO, but only Sb(V) originating from Sb(III) oxidation was adsorbed effectively by BMO. Introduced Fe(II) was chemically oxidized to FeOOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe-Mn oxides (BFMO). The BMO part of the BFMO mainly oxidized and the FeOOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As(III) and Sb(III), the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe(II), As(III) and Sb(III) accelerated the oxidation of Mn(II) but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn(II) in aquatic ecosystems, with or without Fe(II).

Biosorption of antimony oxyanions by brown seaweeds: Batch and column studies

Abstract: The removal of contaminants from wastewaters has becoming more stringent. Mine water, for instance, has been subjected to stricter discharge limits imposed on various contaminants, such as antimony. In the present study, two brown seaweeds, Sargassum muticum and Ascophyllum nodosum , were studied as potential biosorbents for antimony(III) and antimony(V). Biosorption of Sb(III) by S. muticum was found to be a fast process and equilibrium data were described by both Langmuir and Freundlich models. Maximum biosorption capacities, predicted by Langmuir model, for Sb(III) on S. muticum were 2.1 ± 0.6 and 4 ± 1 mg g −1 , at pH 2 and 7, respectively. The pH and the presence of some metals moderately affected Sb(III) biosorption. No significant effect was observed with the presence of chloride, nitrate, sulphate or phosphate. These results suggested good perspectives for a practical application of brown seaweed to remove Sb from mining-influenced waters. A packed-bed column was tested for Sb(III) removal from heavy and low-contaminated solutions and good quality effluents were obtained.

Activation of an Au-Cl Bond by a Pendent SbIII Lewis Acid: Impact on Structure and Catalytic Activity.

Abstract: With the objective of identifying new coordination modes of ambiphilic ligands, we have investigated the bidentate Sb/P ligands (o-(Ph2 P)C6 H4 )SbCl2 (LCl ) and (o-(Ph2 P)C6 H4 )SbPh2 (LPh ). Reaction of these ligands with (tht)AuCl affords the monoligated species LCl AuCl (1) and LPh AuCl (2), respectively, in which the antimony centers are only weakly engaged with the coordinated gold atom. Treatment of 1 with PPh3 induces an intramolecular transfer of a chloride ligand from gold to antimony to form the zwitterionic species o-(Cl3 Sb)C6 H4 (Ph2 P)Au(PPh3 ) (3). Natural bond orbital (NBO) calculations show that the antimony and gold centers are involved in weak Sb→Au and Au→Sb interactions, the latter reflecting the Lewis acidity of the pendent antimony group. Finally, we demonstrate that the ability of the antimony center in 1 to abstract a gold-bound chloride in the presence of a Lewis basic substrate may be utilized to activate the gold center for the electrophilic cycloisomerization of propargylic amides.

Elusive Antimony-Centered Radical Cations: Isolation, Characterization, Crystal Structures, and Reactivity Studies.

Abstract: One-electron oxidation of the stibines Aryl3Sb (1, Aryl=2,6-iPr2-4-OMe-C6H2; 2, Aryl=2,4,6-iPr3-C6H2) with AgSbF6 and NaBArylF4 (ArylF=3,5-(CF3)2C6H3) afforded the first structurally characterized examples of antimony-centered radical cations 1.+[BArylF4]− and 2.+[BArylF4]−. Their molecular and electronic structures were investigated by single-crystal X-ray diffraction, electron paramagnetic resonance spectroscopy (EPR) and UV/Vis absorption spectroscopy, in conjunction with theoretical calculations. Moreover, their reactivity was investigated. The reaction of 2.+[BArylF4]− and p-benzoquinone afforded a dinuclear antimony dication salt 32+[BArylF4]2−, which was characterized by NMR spectroscopy and X-ray diffraction analysis. The formation of the dication 32+ further confirms that the isolated stibine radical cations are antimony-centered.

Graphene Oxide‐Modified Electrode Coated with in‐situ Antimony Film for the Simultaneous Determination of Heavy Metals by Sequential Injection‐Anodic Stripping Voltammetry

Abstract: The proposed chemically modified electrode was graphene oxide that was synthesized via Hummer's method followed by reduction of antimony film by in-situ electrodeposition. The experimental process could be concluded in three main steps: preparation of antimony film, reduction of analyte ions on the electrode surface and stripping step under the conditions of square wave anodic stripping voltammetry (SWASV). A simple and rapid approach was developed for the determination of heavy metals simultaneously based on a sequential injection (SI), an automated flow-based system, coupled with voltammetric method using antimony-graphene oxide modified screen-printed carbon electrode (SbF-GO-SPCE). The effects of main parameters involved with graphene oxide, antimony and measurement parameters were also investigated. Using SI-SWASV under the optimal conditions, the proposed electrode platform has exhibited linear range from 0.1 to 1.5 M. Calculated limits of detection were 0.054, 0.026, 0.060, and 0.066 μM for Cd(II), Pb(II), Cu(II) and Hg(II), respectively. In addition, the optimized method has been successfully applied to determine heavy metals in real water samples with acceptable accuracy of 94.29 – 113.42 % recovery.