Structure and properties of lead and lead sulfide nanoparticles in natural zeolite

We have synthesized lead and lead sulfide nanoparticles embedded in a natural zeolite (clinoptilolite) matrix by a simple hydrothermal process. The process steps involve the partial removing of the natural cations in clinoptilolite, the ion-exchange process to enclose Pb ions and nanoparticles and finally a sulfuration process at different temperatures to obtain lead sulfide phases in the zeolite matrix. The samples were studied by X-ray diffraction, diffuse reflectance spectroscopy, energy dispersive X-ray spectroscopy, X-ray photon spectroscopy and transmission electron microscopy. The experimental results show the inclusion of three Pb species with different valence states after the Pb ion-exchange step, namely Pb²⁺, Pb⁴⁺, and Pb⁰. At the end of the process, two simultaneous lead sulfide crystalline phases, PbS (Galena) and PbS₂ (tetragonal) were synthesized in the clinoptilolite matrix. The optical absorption spectra of the samples show the exciton absorption peaks typical of colloidal PbS nanoparticles. The average size of the PbS nanoparticles was about 10 nm and their crystalline structure was determined from diffraction electron patterns. The high-pressure phase PbS₂ was also identified and its formation was attributed to the influence of the special conditions of clinoptilolite matrix as crystallization media to induce some selective nucleation process of this crystalline phase.     

Tailoring synthesis of Ni3S2 nanosheets with high electrochemical performance by electrodeposition

Nickel sulfide nanosheets with high electrochemical performance were successfully synthesized by an electrochemical deposition method. It is interesting to notice that the size, thickness and surface area were simply tailored by adjusting the initial potential during synthesis without changing other reaction conditions. The highest electrochemical performance was achieved on the nickel sulfide sample prepared at initial potential of ?0.9?V. This sample not only presented high specific capacitance at low current density (1958.0F?g^?1 at 3.3?A?g^?1), but also exhibited excellent high rate performance (672.8F?g^?1 at 98.7?A?g^?1). To the best of our knowledge, these values are in the highest level as compared with other works. The high electrochemical performance of nickel sulfide sample originates from its thin thickness.     

Removal of sulfides from waters and wastewaters by activated carbon

The use of activated carbon treatment for removal of sulfides from wastewaters has been shown to be an effective process. Preliminary results show dissolved sulfide reductions of 36 to 95% were achieved using Darco S51 powdered activated carbon at a dosage of 1000 mg/l to treat a synthetic wastewater containing 1–50 mg/l of dissolved sulfide. Experiments were performed over a pH range of 6.0 to 12.0; the minimum residual sulfide concentration is achieved at pH ∼ 8.5. The removal of sulfides by activated carbon can be adequately described using either a Langmuir or Freundlich isotherm. Various brands and types of activated carbon were investigated, resulting in different adsorption characteristics. The rate of sulfide removal is fast, generally reaching equilibrium in a very short time (t < 30 min). Adsorption capacities in the range of 150 to 900 μmol/g of activated carbon were observed resulting in C_e being in the range of 6.8 to 10.0 mg S/l for large applied sulfide concentrations (in the absence of heavy metals). The presence of several foreign ions (NH₄⁺, CN⁻, etc.) interfered with the removal of dissolved sulfide by activated carbon adsorption due to a competition for the active sites by the sulfide species and the contaminant ions.     

Effect of sulfide ions on the stress corrosion behaviour of Al-brass and Cu10Ni alloys in salt water

The stress corrosion cracking (SCC) behavior of Al-brass and Cu10Ni alloys was investigated in 3.5% NaCl solution in absence and in presence of different concentrations of Na₂S under open-circuit potentials using the constant slow strain rate technique. The results indicated that the Cu10Ni alloy is more susceptible to stress corrosion cracking than as-received Al-brass at strain rate of 3.5 × 10^–6 s^–1 in 3.5% NaCl in presence of high concentration of sulfide ions (1000 ppm). The sulfide ions (up to 500 ppm) has no effect on the stress corrosion cracking of the annealed Al-brass in 3.5% NaCl at two strain rates of 7.4 × 10^–6 and 3.5 × 10^–6 s^–1. The results support film rupture for Al-brass and sulfide stress corrosion cracking assisted with pitting corrosion for Cu10Ni at slip steps as the operating mechanisms.     

Structural and optical properties of amorphous and crystalline antimony sulfide thin-films

Smooth and compact thin films of amorphous and crystalline antimony sulfide (Sb₂S₃) were prepared by radio frequency sputtering of an Sb₂S₃ target. As-deposited films are amorphous. Polycrystalline antimony sulfide films composed of ∼ 500 nm grains are obtained by annealing the as-deposited films at 400 °C in sulfur vapors. Both amorphous and crystalline antimony sulfide have strong absorption coefficients of 1.8 × 10⁵ cm^− 1 at 450 nm and 7.5 × 10⁴ cm^− 1 at 550 nm, and have direct bandgaps with band energies of 2.24 eV and 1.73 eV, respectively. These results suggest the potential use of both amorphous and crystalline antimony sulfide films in various solid state devices.     

Redox Tuning in Crystalline and Electronic Structure of Bimetal–Organic Frameworks Derived Cobalt/Nickel Boride/Sulfide for Boosted Faradaic Capacitance

The development of efficient electrode materials is a cutting‐edge approach for high‐performance energy storage devices. Herein, an effective chemical redox approach is reported for tuning the crystalline and electronic structures of bimetallic cobalt/nickel–organic frameworks (Co‐Ni MOFs) to boost faradaic redox reaction for high energy density. The as‐obtained cobalt/nickel boride/sulfide exhibits a high specific capacitance (1281 F g^?1 at 1 A g^?1), remarkable rate performance (802.9 F g^?1 at 20 A g^?1), and outstanding cycling stability (92.1% retention after 10 000 cycles). An energy storage device fabricated with a cobalt/nickel boride/sulfide electrode exhibits a high energy density of 50.0 Wh kg^?1 at a power density of 857.7 W kg^?1, and capacity retention of 87.7% (up to 5000 cycles at 12 A g^?1). Such an effective redox approach realizes the systematic electronic tuning that activates the fast faradaic reactions of the metal species in cobalt/nickel boride/sulfide which may shed substantial light on inspiring MOFs and their derivatives for energy storage devices.     

Effect of sulfide concentration on the location of the metal precipitates in inversed fluidized bed reactors

The effect of the sulfide concentration on the location of the metal precipitates within sulfate-reducing inversed fluidized bed (IFB) reactors was evaluated. Two mesophilic IFB reactors were operated for over 100 days at the same operational conditions, but with different chemical oxygen demand (COD) to SO₄²⁻ ratio (5 and 1, respectively). After a start up phase, 10 mg/L of Cu, Pb, Cd and Zn each were added to the influent. The sulfide concentration in one IFB reactor reached 648 mg/L, while it reached only 59 mg/L in the other one. In the high sulfide IFB reactor, the precipitated metals were mainly located in the bulk liquid (as fines), whereas in the low sulfide IFB reactor the metal preciptiates were mainly present in the biofilm. The latter can be explained by local supersaturation due to sulfide production in the biofilm. This paper demonstrates that the sulfide concentration needs to be controlled in sulfate reducing IFB reactors to steer the location of the metal precipitates for recovery.     

Electrical properties of La2S3-doped calcium sulfide solid electrolyte

In order to consider the application of La₂S₃-doped calcium sulfide to a solid electrolyte for metal sulfide systems, its electrical properties have been investigated, based on a galvanic cell technique and conductivity measurements at various temperatures and sulfur pressures. The following cell was employed; Cu,Cu₂S |CaS (La₂S₃)| FeS, Fe. The values of the electromotive force obtained in this cell were roughly consistent with the theoretical ones. Based on conductivity measurements under various sulfur pressures at 700–900°C, the electrical conduction of La₂S₃-doped calcium sulfide was found to be ionic at sulfur pressures higher than 10^?6 atm and n-type semiconducting at lower sulfur pressures. The apparent activation energy obtained for the ionic conduction was 19.02 kcal/mol, which was reasonable for the ionic conduction through migration of a Ca²⁺ ion.     

硫化物电化学氧化过程研究

用电化学方法研究了碱性溶液中硫化物在Pt电极上的氧化过程。结果表明，硫离子在－600－＋750mV(vs.SCE）存在两个电化学氧化过程。经热力学、动力学和化学分析证实，在约－400mV时硫离子首先氧化为单质硫及多硫化物，沉积在电极表面；约250mV处，单质硫及多硫化物进一步氧化为硫酸根离子而进入溶液，低电位下的氧化反应是可逆反应，硫离子扩散为控制步骤；高电位下，单质硫进一步氧化为硫酸根离子的反应是不可逆反应，而两反应过程密切相关。     

Deposition and annealing effect on lanthanum sulfide thin films by spray pyrolysis

Lanthanum sulfide thin films were prepared on glass substrates from aqueous medium using spray pyrolysis technique. The effect of preparative parameters such as substrate temperature and solution concentration on the films was studied. The lanthanum sulfide films were annealed in air at 300 °C for 2 h. The films were characterized by X-ray diffraction (XRD), optical microscopy, optical absorption, electrical resistivity and thermo-emf measurement techniques. The XRD studies revealed that the as deposited films are amorphous, while annealed films are polycrystalline. The optical band gap of the as deposited film is decreased from 2.5 to 2.2 eV after annealing due to improvement in crystallinity. The electrical resistivity is of the order of 10⁴-10⁵ Ω cm and showed semiconducting behaviour. Thermo-emf measurement revealed that the conductivity of lanthanum sulfide is p-type.     

Assessment of odorous VOCs released from a main MSW landfill site in Istanbul-Turkey via a modelling approach

An air pollution modeling study was conducted to investigate the odorous effects of volatile organic compounds (VOCs) emissions from a sanitary landfill area on ambient air quality. The atmospheric dispersion of hydrogen sulfide (H₂S) and 22 VOCs was modeled. Industrial Source Complex v3 Short Term (ISCST3) model was used to estimate hourly concentrations of odorous VOCs over the nearest residential area. Odor thresholds of VOCs of interest were also found in the literature. Results showed that short-term averages of three odorous VOCs, namely ethyl mercaptan, methyl mercaptan and hydrogen sulfide, exceeded their odor thresholds, which are reported to be 0.022, 0.138 and 11.1 μg/m³, respectively, at several points within the domain. Their highest concentrations within Gokturk County were estimated to be 0.09387 μg/m³ for ethyl mercaptan, 0.07934 μg/m³ for methyl mercaptan and 6.315 μg/m³ for hydrogen sulfide. Short-term model results revealed the occasional odor problems being reported for Gokturk County. Hourly concentrations were used to obtain frequencies of odor episodes in Gokturk County via a probability analysis. The results showed that ethyl mercaptan concentrations did not exceed its odor threshold during more than 8.84% of the time. Similarly, the maximum odor episode frequencies for methyl mercaptan and hydrogen sulfide were 0.98% and 0.34% of the time, respectively.     

Tin sulfide thin films and Mo/p-SnS/n-CdS/ZnO heterojunctions for photovoltaic applications

Tin sulfide (SnS) is one of the most promising materials for photovoltaics. Here we report on the preparation as well as chemical, structural and physical characterization of the Mo/p-SnS/n-CdS/ZnO heterojunctions. The SnS thin films were grown by hot wall deposition method on the Mo-coated glass substrates at 270-350 °C. The crystal structure and elemental composition were examined by X-ray diffraction and Auger electron spectroscopy methods. The CdS buffer layers were deposited onto the SnS films by chemical bath deposition. The ZnO window layers were deposited by a two step radio frequency magnetron sputtering, resulting in a ZnO bilayer structure: the first layer consists of undoped i-ZnO and the second of Al-doped n-ZnO. The best junctions have an open circuit voltage of 132 mV, a short circuit current density of 3.6 mA/cm², a fill-factor of 0.29 and efficiency up to 0.5%.     

Instantaneous emission brightness kinetics of zinc sulfide based electroluminescent thin-film emitters

Excited with triangular voltage pulses, electroluminescent thin-film emitters based on manganese-doped zinc sulfide exhibit a two-stage buildup and decay of the instantaneous emission brightness. The fast decay stage corresponds to the Mn²⁺ ion relaxation in zinc sulfide at a time constant of 1.4 ms. Preceding the fast stage, the slow decay stage has a time constant ten times greater and accounts for a markedly increased afterglow (phosphorescence) duration. The luminance level corresponding to the transition from the first to second stage is virtually independent of the applied voltage and the charge passed through the luminophor.     

The Effect of Thiol Structure on Allyl Sulfide Photodegradable Hydrogels and their Application as a Degradable Scaffold for Organoid Passaging

Intestinal organoids are useful in vitro models for basic and translational studies aimed at understanding and treating disease. However, their routine culture relies on animal-derived matrices that limit translation to clinical applications. In fact, there are few fully defined, synthetic hydrogel systems that allow for the expansion of intestinal organoids. Here, an allyl sulfide photodegradable hydrogel is presented, achieving rapid degradation through radical addition-fragmentation chain transfer (AFCT) reactions, to support routine passaging of intestinal organoids. Shear rheology to first characterize the effect of thiol and allyl sulfide crosslink structures on degradation kinetics is used. Irradiation with 365 nm light (5 mW cm⁻²) in the presence of a soluble thiol (glutathione at 15 × 10⁻³ m ), and a photoinitiator (lithium phenyl-2,4,6-trimethylbenzoylphosphinate at 1 × 10⁻³ m ), leads to complete hydrogel degradation in less than 15 s. Allyl sulfide hydrogels are used to support the formation of epithelial colonies from single intestinal stem cells, and rapid photodegradation is used to achieve repetitive passaging of stem cell colonies without loss in morphology or organoid formation potential. This platform could support long-term culture of intestinal organoids, potentially replacing the need for animal-derived matrices, while also allowing systematic variations to the hydrogel properties tailored for the organoid of interest.     

Influence of substrate temperature on the physical properties of thermally evaporated nanocrystalline bismuth sulfide thin films

Nanocrystalline bismuth sulfide thin films were deposited on glass substrate by thermal evaporation technique using the solvothermally synthesized nanometer-sized bismuth sulfide powder as the source material. X-ray diffraction (XRD) analysis revealed that the films are polycrystalline in nature with orthorhombic structure. The crystallinity of the thin films improved with substrate temperature, and the estimated crystallite size are in the nanometer regime. Scanning electron microscope (SEM) analysis showed homogenous distribution of grains with well defined grain boundaries. The optical transmittance of the nanocrystalline bismuth sulfide thin films increases with the increase in substrate temperature, and the optical transition was found to be direct and allowed. The estimated optical band gap energy was found to decrease with the increase in substrate temperature. The electrical resistivity of the bismuth sulfide thin films is of the order of 10⁻⁴ Ω-cm and exhibits semiconductor nature. Experimental results demonstrate that the structural, optical and electrical properties of bismuth sulfide thin films have strong dependence on the substrate temperature.     

Directed growth of 1D cadmium sulfide by chemically anchored Al2O3 and ZnO nanoparticles

Cadmium sulfide nanowires were synthesized on in-situ generated alumina nanoparticles using a one pot hydrothermal method. As grown hexagonal-phase cadmium sulfide nanowires have diameters ranging from 40 to 50 nm. Mechanistic aspects reveal that the alumina template based growth of cadmium sulfide nanowires is due to the fact that S²⁻ ions will preferably attach to the aluminum due to the Lewis acidic character of Al³⁺ (~ 0.5 on Brown's scale of average Lewis acid strength). To support the proposed mechanism, we have further shown the growth of cadmium sulfide nanowires on zinc ions having similar Lewis acidic strength.     

Effect of SO2 impurity on the optical transmission of As2S3 glass

To assess the effect of sulfur dioxide impurity on the optical properties and absorption spectrum of glassy arsenic sulfide, we have prepared As₂S₃ glass samples containing 0.01 to 0.12 wt % SO₂ and have measured their transmission spectra in the range 500–5000 cm^?1. The extinction coefficient of sulfur dioxide in glassy arsenic sulfide, evaluated from the intensity of the 1158-cm^?1 absorption band, is 10.0 ± 0.7 cm^?1/wt%.     

Preparation and study of thickness dependent electrical characteristics of zinc sulfide thin films

Zinc sulfide thin films have been deposited onto glass substrates by chemical bath deposition. The various deposition parameters such as volume of sulfide ion source, pH of bath, deposition time, temperature etc are optimized. Thin films of ZnS with different thicknesses of 76–332 nm were prepared by changing the deposition time from 6–20 h at 30° C temperature. The effect of film thickness on structural and electrical properties was studied. The electrical resistivity was decreased from 1.83 × 10⁵ Ω-cm to 0.363 × 10⁵ Ω-cm as film thickness decreased from 332 nm to 76 nm. The structural and activation energy studies support this decrease in the resistivity due to improvement in crystallinity of the films which would increase the charge carrier mobility and decrease in defect levels with increase in the thickness.     

Low temperature aqueous chemical synthesis of CdS sensitized ZnO nanorods

Cadmium sulfide nanoparticles (CNPs) sensitized zinc oxide nanorod arrays (ZNRs) were synthesized in the two step deposition process at relatively low temperature. The vertically aligned ZNRs were grown on the conducting glass substrates (FTO) using aqueous chemical method, followed by the deposition of CNPs at 70 °C using chemical bath deposition (CBD) technique. The samples were characterized by optical absorption, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). Further, the photoelectrochemical (PEC) performance of ZNRs with and without CNPs sensitization was tested in Na₂S-NaOH-S and Na₂SO₄ electrolyte, respectively. When the CNPs are coated on the ZNRs, the optical absorption is enhanced and band edge is shifted towards visible region (525 nm) as compared with ZNRs (375 nm). The sample sensitized with CNPs shows higher photoelectrochemical (PEC) performance with maximum short circuit current of (I_sc) 2.60 mA/cm².     

Tactical hybrids of Li+-conductive dry polymer electrolytes with sulfide solid electrolytes: Toward practical all-solid-state batteries with wider temperature operability

The chemical vulnerability of sulfide solid electrolyte (SE) materials to organic polar solvents complicates the wet-slurry fabrication of sheet-type electrodes and SE films for practical all-solid-state Li batteries (ASLBs). Moreover, the disruption of interfacial Li⁺ conduction by binders is problematic. This could be relieved by blending with liquid electrolytes but at the expense of the ASLBs’ thermal stability. In this study, a new tactical approach to hybridize sulfide SEs with thermally stable and slurry-fabricable dry polymer electrolyte (DPE)-type binders is reported. Along with their practicability, ester solvents bearing bulky hydrocarbons, such as benzyl acetate, dissolve both polymers and Li salts (e.g., LiTFSI) while undamaging sulfide SEs. The use of the DPE-type binder, NA-LiTFSI (NA: nitrile butadiene rubber-poly(1,4-butylene adipate)), for LiNi_0.70Co_0.15Mn_0.15O₂ (NCM) electrodes significantly improves their electrochemical performance at 30 °C. Moreover, NA-LiTFSI is highly functional at 70 °C (from 180 to 200 mA h g⁻¹ and from 84.2 to 91.8% for initial Coulombic efficiency) and applicable for other electrodes, such as graphite (from 265 to 330 mA h g⁻¹) and Li₄Ti₅O₁₂, which is in stark contrast to the solvate ionic liquid-type binder Li(G3)TFSI. Finally, pouch-type NCM/graphite ASLBs employing electrodes made of NA-LiTFSI binders were also fabricated.