Additional Sulfur Research Articles

Large single crystal diamond grown in FeNiMnCo–S–C system under high pressure and high temperature conditions**Project supported by the National Natural Science Foundation of China (Grant No. 51172089), the Education Department of Henan Province, China (Grant No. 12A430010), and the Fundamental Research Funds for the Universities of Henan Province, China (Grant No. NSFRF140110).

Large diamonds have successfully been synthesized from FeNiMnCo–S–C system at temperatures of 1255–1393 °C and pressures of 5.3–5.5 GPa. Because of the presence of sulfur additive, the morphology and color of the large diamond crystals change obviously. The content and shape of inclusions change with increasing sulfur additive. It is found that the pressure and temperature conditions required for the synthesis decrease to some extent with the increase of S additive, which results in left down of the V-shape region. The Raman spectra show that the introduction of additive sulfur reduces the quality of the large diamond crystals. The x-ray photoelectron spectroscopy (XPS) spectra show the presence of S in the diamonds. Furthermore, the electrical properties of the large diamond crystals are tested by a four-point probe and the Hall effect method. When sulfur in the cell of diamond is up to 4.0 wt.%, the resistance of the diamond is 9.628×105 Ω·cm. It is shown that the large single crystal samples are n type semiconductors. This work is helpful for the further research and application of sulfur-doped semiconductor large diamond.

Peculiar Magnetic Features and Superconductivity in Sulfur Doped Amorphous Carbon

We report on magnetic studies of inhomogeneous commercial and synthesized amorphous carbon (a-C) and a-C doped with sulfur (a-CS) powders which exhibit (i) peculiar magnetic behavior and (ii) traces of two superconducting (SC) phases TC ~ 33 and at 65 K. (i) The temperature dependence of zero-field-cooled (ZFC) curves measured up to room temperature show well distinguished elusive peaks at around 50–80 K, and their origin is not yet known. These peaks are totally washed-out in the second ZFC sweeps and in the FC branches as well. As a result, in the vicinity of the peaks, the FC curves lie below the ZFC peaks (FC < ZFC), a phenomenon which is rarely observed. These magnetic anomalies are intrinsic properties of a-C and a-CS materials (ii) SC was observed in three different a-C sources: (a) The commercial a-C powder contains 0.21% of sulfur and it is suggested that two different a-CS phases (at 33 and 65 K) are the origin of the two SC states observed. The compositions of these two phases are not yet unknown. The small SC volume fractions of the 33 K phase can be enhanced by a solid reaction with additional sulfur at 250 °C; (b) the synthesized (a-C) powder (obtained from decomposition of sucrose) is not SC. However, when mixed with sulfur and heated at 400 °C under a protective atmosphere, the a-CS powder obtained also show traces of a SC phase at TC = 42 K; (c) The same occurs in a-C thin films. The as-grown films are not SC but a SC phase at TC = 34 K emerges after the films were reacted with sulfur at elevated temperatures. It is concluded, therefore, that all SC phases observed are due to different unknown a-CS phases. Since the a-C and a-CS powders possess SC and magnetic states, we believe that these powders resemble the high TC curates and Fe-As based systems in which the SC and the magnetic states are closely related to each other.

Effects of Cadmium Treatment on the Uptake and Translocation of Sulfate in Arabidopsis thaliana.

Cadmium (Cd) is a highly toxic and non-essential element for plants, whereas phytochelatins and glutathione are low-molecular-weight sulfur compounds that function as chelators and play important roles in detoxification. Cadmium exposure is known to induce the expression of sulfur-assimilating enzymes and sulfate uptake by roots. However, the molecular mechanism underlying Cd-induced changes remains largely unknown. Accordingly, we analyzed the effects of Cd treatment on the uptake and translocation of sulfate and accumulation of thiols in Arabidopsis thaliana Both wild type (WT) and null mutant (sel1-10 and sel1-18) plants of the sulfate transporter SULTR1;2 exhibited growth inhibition when treated with CdCl2 However, the mutant plants exhibited a lower growth rate and lower Cd accumulation. Cadmium treatment also upregulated the transcription of SULTR1;2 and sulfate uptake activity in WT plants, but not in mutant plants. In addition, the sulfate, phytochelatin and total sulfur contents were preferentially accumulated in the shoots of both WT and mutant plants treated with CdCl2, and sulfur K-edge XANES spectra suggested that sulfate was the main compound responsible for the increased sulfur content in the shoots of CdCl2-treated plants. Our results demonstrate that Cd-induced sulfate uptake depends on SULTR1;2 activity, and that CdCl2 treatment greatly shifts the distribution of sulfate to shoots, increases the sulfate concentration of xylem sap and upregulates the expression of SULTRs involved in root-to-shoot sulfate transport. Therefore, we conclude that root-to-shoot sulfate transport is stimulated by Cd and suggest that the uptake and translocation of sulfate in CdCl2-treated plants are enhanced by demand-driven regulatory networks.

Enhancement of Lithium-Sulfur Batteries By Introducing Metal-Organic-Framework (MOF) Coated Separators

Sulfur has received high attention as an advanced cathode material due to the advantages of its high theoretical energy density of 2600Wh/kg, environmental friendliness, and cost-benefit. Despite of its many strong points in lithium sulfur batteries, it is not sufficient to practically use the sulfur cathode in commercial lithium-ion batteries due to the active material loss and the polysulfides shuttling effect. To address the above-mentioned challenges, two main approaches have been intensively investigated: a) Control of dissolved polysulfide intermediates in electrolyte by designing scaffolds of sulfur or electrolytes. b) Confinement of polysulfides within the sulfur cathode side by introducing an additional interlayer in-between sulfur cathode and separator. However, there are few approaches on a separator only to prevent the migration of sulfur species to the anode for electrochemically stable lithium sulfur batteries. Here, we suggest inserting metal-organic-framework (MOF) coated separator by using simple surface modifying strategy with polydopamine (PDA). MOF has interesting properties such as high porosity, chemical absorption and catalytic property. MOF coated separator effectively retards the diffusion of polysulfides to counter electrode due to its physicochemical sorption property. The sulfur battery with MOF coated separator shows an improved cycle performance and high specific capacity, compared to pristine separator. Figure 1

Facile synthesis of high performance non-noble-metal electrocatalyst Fe–N–S/C for oxygen reduction reaction in acidic solutions

The development of non-noble metal catalysts is of great interest due to their significant potential application in both fuel cell system and metal-air batteries, particularly when considering long term commercial deployment. Fe/N/C is a promising non-Pt electrocatalyst for the oxygen reduction reaction (ORR), but its catalytic activity is considerably inferior to that of Pt in acidic medium. In this paper, an improved Fe/N/S/C catalyst (denoted as Fe–N–S/C) is presented. Nitrogen-sulfur-iron-doped porous carbon material is synthesized by the pyrolysis of dicyandiamide, a kind of abundant and inexpensive compound, with thiourea as additional sulfur source in argon atmosphere. The Fe–N–S/C shows excellent performance for the ORR with the onset and half-wave potential at 0.89 and 0.78 V (vs.RHE) in 0.1 M H2SO4 solution, respectively, which are significantly higher compared to those of the catalysts derived from only dicyandiamide (0.85 and 0.75 V). Our results indicate that as compared to the commercial 20 % Pt/C catalyst, the synthesized catalyst exhibits not only higher current density and long-term durability but also higher tolerance to methanol poisoning. More importantly, the synthetic method is simple and inexpensive.

Utilisation of aromatic organosulfur compounds as sulfur sources by Lipomyces starkeyi CBS 1807.

Aromatic organosulfur compounds that contain aryl carbon-sulfur bonds are rare in nature but occur frequently in industrial processes and products. The utilisation of aryl sulfur compounds as a sulfur source has not been described previously among the budding yeasts (phylum Ascomycota, sub-phylum Saccharomycotina). A total of 31 strains representing 30 species and 28 genera of the budding yeasts were assayed for utilisation of benzene sulfonate as source of sulfur. Lipomyces starkeyi CBS 1807 was the only strain in this screen that was able to utilise benzene sulfonate as a sulfur source. Further study of L. starkeyi demonstrated that it could also utilise methyl phenyl sulfoxide, 1-naphthalene sulfonate, 2-naphthalene sulfonate, 1-anthraquinone sulfonate and 2-anthraquinone sulfonate as sulfur sources but not diphenylsulfone. This study represents the first reported case of the utilisation of sulfonated naphthalenes and anthraquinones as sulfur sources by a fungus. However, it should be stressed that the remaining 30 strains in this study were not assayed for the utilisation of these additional aryl sulfur compounds as sulfur sources. The present study highlights the potential of L. starkeyi and related species as a source of novel enzyme activities with possible applications in chemical manufacturing, disposal of xenobiotics and bioremediation.

The effect of additional sulfur on solution-processed pure sulfide Cu2ZnSnS4 solar cell absorber layers

ABSTRACTTo reduce the amount of chalcogen needed in the post-annealing process, we demonstrate significantly increased sulfur incorporation into pure sulfide CZTS films achieved by increasing the thiourea content of DMSO-based precursor solution. The increase of sulfur content was confirmed by thermogravimetric analyses (TGA). To understand how the elemental distribution across the CZTS layer is affected by extra thiourea, a systematic compositional study was carried out using X-ray photoelectron spectroscopy (XPS). XPS depth profiling reveals increased sulfur incorporation in the final CZTS films when more thiourea is added to the solution. The grain size was reduced slightly with increased sulfur content and the surface morphology was changed significantly. The effect on the surface of the CZTS film has been investigated using scanning electron microscopy (SEM), Raman spectroscopy, and XPS. External-quantum-efficiency (EQE) measurements with an electrolyte contact were used to investigate the optoelectronic properties of the deposited CZTS films.

Hydrogen sulfide production during yeast fermentation causes the accumulation of ethanethiol, S-ethyl thioacetate and diethyl disulfide

Hydrogen sulfide (H2S) is produced by yeast during winemaking and possesses off-flavors reminiscent of rotten eggs. The production of H2S during fermentation has also been associated in the finished wine with the rise of additional volatile sulfur compounds (VSCs) with strong aromas of cooked onions and vegetables. To characterize these more complex VSCs produced from H2S, we performed fermentations in synthetic grape juice. H2S production was manipulated experimentally by feeding increasing concentrations of sulfate to mutant strains that are unable to incorporate H2S efficiently as part of the sulfur assimilation pathway. In finished wines from these mutants, three VSCs – ethanethiol, S-ethyl thioacetate and diethyl disulfide – increased proportionally to H2S. 34S-labeled sulfate fed to the MET17-deleted strain was incorporated into same three VSCs, demonstrating that they are formed directly from H2S.

Bifunctional periodic mesoporous organosilicas with sulfide bridges as effective sorbents for Hg(II) extraction from environmental and drinking waters

A well-ordered two-dimensional hexagonal periodic mesoporous organosilica have been prepared with a high content of disulfide groups in the pore wall (PMO-S-S). This material was obtained by co-condensation of bis(triethoxysylilpropyl)disulfide and tetraethyl orthosilicate under acidic conditions, using non-ionic surfactant P123 as the template. In order to obtain bifunctional disulfide-bridged materials (PMO-S-S-MTTZ and PMO-S-S-MP), the PMO-S-S was modified in a second step with the organic derivatives of 5-mercapto-1-methyltetrazole (MTTZ) or 2-mercaptopyridine (MP) with sulphur and nitrogen active groups in their molecular structures. The characterization of the materials was carried out by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, 13C MAS-NMR, 29Si MAS-NMR, FTIR, elemental and thermogravimetric analysis. All prepared materials showed excellent adsorption efficiency and selectivity for Hg(II). The results confirmed the existence of additional active sulphur and nitrogen groups on the material surface, in addition to the disulfide groups of the framework, gave a significant enhancement of Hg(II) maximum adsorption capacity of the materials, being the highest Hg(II) adsorption capacity obtained 437 mg g−1 at pH 5. The prepared materials could be potential sorbents for the extraction of this heavy metal from environmental and drinking waters.

Discussion on the purity and the crystallization of CZTS compound

Cu2ZnSnS4 is a new material with low extraction cost. It belongs to Cu–Zn–Sn–S quaternary system and has recently attracted great attention as promising photovoltaic material. Due to its interesting properties such as a band-gap around 1.5eV and a large absorption coefficient in the order of 104cm−1. This compound is considered as ideal for effective phonon absorption and photo-generation. Since the sulfur is an important element in the stoichiometric composition, the effect of its content on the purity, the stability and the crystallization of this material has been taken in account. High purity Cu2ZnSnS4 single phase compound, with an excess sulfur starting concentration lying in the range 3–20wt%, could be obtained. In these conditions, Cu2ZnSnS4 alloy has been synthesized and vertically well textured along the melt flow. Depending on the additional sulfur amount at the starting charge, it was possible to control both the solidification conditions and the morphology of Cu2ZnSnS4 phase. As a result, the solidification process allowed us to control the as grown crystal under stationary stable regime.

Preparation of Ni—W aromatic hydrocarbon hydrogenation catalysts by breaking reverse emulsions or suspensions of a precursor in hydrocarbon feedstock

Reverse emulsions (hydrocarbon feedstock)/(aqueous precursor solution) for synthesizing aromatic hydrocarbon hydrogenation catalysts have been prepared using the water-soluble salts (NH4)2WS4 and Ni(NO3)2 · 6 H2O as precursors. It has been found that the optimum stabilizer for the emulsions is the nonionic surfactant SPAN-80. The resulting emulsions exhibit low catalytic activity in the hydrogenation of aromatic hydrocarbons; it has been shown that the activity of the systems in hydrodearomatization reactions is adversely affected by the presence of water. A procedure for preparing suspensions of solid precursor particles in a hydrocarbon feedstock by the removal of water from the resulting reverse emulsions has been developed. The catalytic activity of the resulting suspensions in the hydrogenation of aromatic hydrocarbons has been studied using naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as examples. It has been shown that the catalytic activity of the suspensions is higher than that of the reverse emulsions of the same composition. It has been found that the feedstock should be subjected to additional sulfurization with elemental sulfur for further sulfiding the surface of the nickel—tungsten catalyst. The W: Ni molar ratio of 1 : 1 has been found to be optimum.

Effect of copper content and sulfurization process on optical, structural and electrical properties of ultrasonic spray pyrolysed Cu2ZnSnS4 thin films

This paper reports the effect of copper content and of the sulfurization process (using elemental sulfur vapor) on the growth, structure, elemental composition, and on the optical and electrical properties of Cu2ZnSnS4 (CZTS) thin films deposited on glass substrates using ultrasonic Spray Pyrolysis. For this purpose, a series of aqueous solutions consisting of copper (II) and tin (IV) chlorides, zinc (II) acetate and thiourea with different copper concentrations (x = Cu/(Zn + Sn) = 0.8, 1, 1.2 and 1.4 while Zn/Sn = 1) were prepared. X-ray diffraction, raman spectroscopy, scanning electronic microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, ultraviolet–visible–near infrared absorbance spectroscopy and sheet resistance analyses were used to follow the evolution of the investigated properties. The results outlined a Kesterite type CZTS phase and a secondary copper sulfide (Cu2-xS) phase, and their ratio strongly depends on the copper salt concentration and heat-treatment atmosphere. No traces of secondary phases of zinc or tin sulfides are found while high purity CZTS was obtained with the post-sulfurized film at x = 1.2. It was found that the application of additional sulfurization enhances the grain growth to reach 300 nm in size and induces significant improvement of both CZTS crystallinity and electrical conductivity. The optical band gap ranges between 1.44 and 1.57 eV depending on the composition and the sulfur deficiency is strongly reduced leading to Cu-poorer and Zn-richer compounds, as compared to those annealed in nitrogen atmosphere.This study shows promising results, as a first step in developing photovoltaic applications, using sprayed CZTS as absorber.

Catalytic upgrading of soybean oil methyl esters by partial hydrogenation using Pd catalysts

Fatty acid methyl esters derived from soybean oil were partially hydrogenated over three types of catalysts-Pd, Pt, and Ni-supported on SiO2. The effect of the sulfur compounds on catalytic activity of the three noble metals was investigated. In both hydrogenated biodiesel with and without additional sulfur compounds, the turnover frequency (TOF) for partial hydrogenation over Pd/SiO2 was greater than that over the Pt/SiO2 and Ni/SiO2 catalysts. On the other hand, Pt/SiO2 exhibited the most sulfur tolerance. Partially hydrogenated biodiesel were found to have better oxidative stability compared to non-hydrogenated biodiesel.

Synthesis of Sulfur-Doped Carbon Dots by Simple Heating Method

Carbon Dots (C-Dots) was successfully prepared by simple heating method. The effect of additional elemental sulfur on the luminiscent performance of C-Dots was investigated. The preparation, chemical composition and optical properties such as absorbance and band gap energy are studied. The C-Dots were prepared with various mass sulfur 0.5-3.0 g and citric acid-urea was constant, i.e. 1.0 g and 4.0 g, respectively. This study used sulfur from natural deposit in Indonesia. The raw materials were prepared by mixing in pure water. The homogeneous solutions were heated at 225°C for 15 minutes under atmospheric pressure. The color emission of C-Dots is found in the visible light spectrum. The addition of sulfur in C-Dots phosphor caused the shifting of absorbance wavelength, i.e. 350-429 nm. By increasing mass of sulfur, the band gap energy of C-Dots decreased from 2.4 eV to 1.8 eV.

Mercury and methylmercury incidence and bioaccumulation in plankton from the central Pacific Ocean

Open ocean samples of phytoplankton and zooplankton were collected from the central Pacific on board the R/V Kilo Moana in October of 2011. The cruise traveled from Hawaii to Samoa, progressing through a High Nutrient Low Chlorophyll (HNLC) zone, and an equatorial upwelling region. Phytoplankton samples were size fractioned into 0.2–5μm, 5–20μm, and >20μm samples. Methylmercury concentrations were 2.91±2.58pmolg−1 (wet weight) for the overall <200μm size fractions, and highest around the HNLC region. Phytoplankton bioconcentration factors (logBCFs) averaged to 5.69±0.98 and were higher than the values found for coastal regions. Both %MeHg ([MeHg]/[Hg]) and logBCF values indicated that the lowest size fraction had the largest fraction of the HgT as MeHg, signifying enhanced accumulation of MeHg into smaller organisms. Zooplankton vertical net tows were completed from depths of 200m up to ~10m. Zooplankton samples were analyzed for carbon, nitrogen and sulfur in addition to Hg and MeHg at size fractionations of 0.2–0.5mm, 0.5–1.0mm, 1.0–2.0mm and occasionally >2.0mm. Zooplankton abundance and MeHg concentrations both peaked at Stations 3 and 5 (upwelling region). The %MeHg in the organisms was highest in the >2.0mm size class, displaying MeHg bioaccumulation for increasing zooplankton sizes. Separate day and night net tows were collected at Stations 3 and 5 in order to investigate differences due to diurnal migration of zooplankton. There were higher concentrations of MeHg for all sizes in night collections of zooplankton at Station 5, but no discrepancy for Station 3. These results represent some of the few measurements of Hg and MeHg at the base of the open ocean food chain, and are significant as they represent the instigation of bioconcentration into the base of marine food webs.

Synthesis of oleylamine-capped Cu2ZnSn(S,Se)4 nanoparticles using 1-dodecanethiol as sulfur source

Oleyalmine capped Cu2ZnSn(S,Se)4 (CZTSSe) nanoparticles were synthesized by the colloidal method at 240 °C. 1-dodecanethiol (1-DDT), which releases sulfur atoms at high refluxing temperatures, is used as a sulfur source. It was observed that at high temperatures (over 150 °C) 1-DDT decomposes and releases sulfur atoms that combine with selenide ions. The resultant CZTSSe powder was homogenously dispersed in chloroform. Formation of the kesterite structure was identified through X-ray diffraction (XRD) analysis which could be tuned to stannite on the basis of the ratio of S/Se. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) analysis clearly shows the presence of oleylamine on the surface of the nanoparticles. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses indicate the formation of 10–20 nm nearly spherical particles with agglomeration. Energy dispersive X-ray analysis (EDX) analysis further confirms the presence of sulfur in addition to Cu, Zn, Sn, and Se.

From Hemoglobin to Porous N–S–Fe-Doped Carbon for Efficient Oxygen Electroreduction

Nitrogen–sulfur–iron-doped porous carbon material with high surface area (1026 m2 g–1) and large pore size is synthesized by the pyrolysis of hemoglobin, an abundant and inexpensive natural compound, with mesoporous silica foam (MS) as a template and thiocarbamide (TCA) as an additional sulfur source in an argon atmosphere. Our results indicated that as compared to the commercial 20% Pt/C catalyst, the synthesized catalyst exhibits not only higher current density and stability but also higher tolerance to crossover chemicals. More importantly, the synthetic method is simple and inexpensive.

Siberian Traps volcaniclastic rocks and the role of magma-water interactions

The Siberian Traps are one of the largest known continental flood basalt provinces and may be causally related to the end-Permian mass extinction. In some areas, a large fraction of the Siberian Traps volcanic sequence consists of mafic volcaniclastic rocks. Here, we synthesize paleomagnetic, petrographic, and field data to assess the likely origins of these volcaniclastic rocks and their significance for the overall environmental impact of the eruptions. We argue that magma-water interactions, including both lava-water interactions and phreatomagmatic explosions in vents, were important components of Siberian Traps magmatism. Phreatomagmatic episodes may have generated tall water-rich eruption columns, simultaneously promoting removal of highly soluble volcanic gases such as HCl and potentially delivering additional sulfur to the upper atmosphere.

In situ process monitoring during multistage coevaporation of Cu2ZnSnS4 thin films

A multistage coevaporation process for the direct growth of Cu2ZnSnS4 (CZTS) thin films without additional atmospheric sulfurization was investigated. To obtain reproducible CZTS films, in situ process monitoring of the film growth was developed by measuring the apparent substrate temperature (Tpyro) using a pyrometer. After CZTS depositions terminated at various endpoints, ex situ characterization of the film properties was performed to clarify the growth mechanism of the films. The results provided clear evidence that CZTS phase formation was significantly delayed via re-evaporation of Sn–S-based compounds in the early part of the first stage, leading to the initial formation of a dominant (CuS + ZnS) structure that coexisted with a small amount of CZTS. CZTS phase formation was then facilitated by the (CuS + ZnS) precursor via a Cu-rich to Cu-poor sequence with an apparent variation in Tpyro during the second stage, and the slightly segregated CuS phase was nearly consumed under (Zn + Sn + S) fluxes. Consequently, CZTS thin films containing close-packed grains with a single kesterite structure were successfully grown under excess Sn and S fluxes, even at moderate Tsub below 500 °C. The best solar cell with a Glass/Mo/CZTS[Cu/(Zn + Sn) = 0.71, Zn/Sn = 1.6]/CdS/ZnO:Ga structure and a NaF precursor layer yielded an active area (0.170 cm2) efficiency of 3.84% (Voc = 567 mV, Jsc = 11.3 mA/cm2, and FF = 0.603). The diode properties under dark and light conditions were also evaluated.

ChemInform Abstract: Thiol as a Synthon for Preparing Thiocarbonyl: Aerobic Oxidation of Thiols for the Synthesis of Thioamides.

AbstractThe CuCl2‐catalyzed aerobic oxidation of benzylic thiols in the presence of secondary amines offers a convenient synthesis of thioamides without the need of additional sulfur compounds as additives.