Sulfide Films Research Articles

Hierarchically Organized MoS2 Films as Promising Electrodes for Flexible Supercapacitors

The formation of hierarchically organized MoS2 films on various substrates by a hydrothermal method was studied. The influence of synthesis conditions and the substrate (a glass or a flexible carbon paper substrate) on the crystal structure of sulfide films was determined using X-ray powder diffraction (XRD). Scanning electron microscopy (SEM) showed that the films on glass substrates comprised structurally different elements, namely a continuous dense layer of spherical nanoparticles on the surface of which hierarchically organized globular agglomerates of two types are arranged. A molybdenum disulfide shell about 1.5 μm thick, consisting of hierarchically organized nanosheets less than 10 nm thick, was formed on the surface of carbon fibers that make up the carbon paper. Elemental mapping was used to evaluate the homogeneity of the MoS2 film formed on the carbon paper. Atomic force microscopy (AFM) showed that an individual carbon fiber modified with a sulfide film had a mean square roughness of about 13 nm (over an area of about 100 μm2). According to Kelvin-probe force microscopy (KPFM) data, the electron work function of the material was 4.53 eV. The electrochemical characteristics of the manufactured flexible electrode based on a hierarchically organized molybdenum disulfide film were investigated. The specific capacitance and the stability of functional and microstructural properties of the manufactured supercapacitor electrode in 2000 charge–discharge cycles were evaluated. Thus, the proposed strategy is promising for the fabrication of efficient hierarchically organized MoS2 electrodes for flexible supercapacitors.

Synthesis, Structural, Optical and Optoelectrical Properties of the Chemically Deposited Cu2BaGeS4 Thin Films

In this work, thin films of copper barium germanium sulfide (Cu2BaGeS4) were generated via the chemical bath deposition technique. The X-ray diffractometer identified the Cu2BaGeS4 layers’ crystal structure. It showed that the Cu2BaGeS4 films have a hexagonal structure. The EDAX results demonstrated stoichiometric composition, which validated the composition of the Cu2BaGeS4 layers. However, the Cu2BaGeS4 sheets under investigation showed a direct energy gap, as demonstrated by the linear optical analysis, with the E g falling from 1.61 to 1.42 eV as the sample thickness rose from 239 to 463 nm. As the film thickness increased, the refractive index and Urbach energy values improved as well. Additionally, the examined Cu2BaGeS4 sheets’ optoelectrical indices, including optical dielectric constants, electrical conductivity, optical mobility, and optical conductivity, improved with thickness. This work shows that increasing the layer thickness enhanced the magnitudes of the nonlinear optical index of the novel Cu2BaGeS4 sheets. Cu2BaGeS4 layers tended to acquire p-type properties, as demonstrated by the hot probe test.

Molecular Precursor Approach to Sulfur-Free CuInSe2: Replacing Thiol Coordination in Soluble Metal Complexes.

Solution-processed CuInSe2 films have generally relied on sulfide or sulfoselenide precursor films that, during the grain growth process, hamper the growth of thicker films and lead to the formation of a fine-grain layer. However, recent research has indicated that sulfur reduction in the precursor film modifies the grain growth mechanism and may enable the fabrication of thicker absorbers that are free of any fine-grain layer. In this work, we pursue direct solution deposition of sulfur-free CuInSe2 films from the molecular precursor approach. To this end, we tune the amine-thiol reactive solvent system and study the changes to the resulting soluble complexes through a combination of analytical techniques. We show that by reactively dissolving indium(III) selenide and selenium in solutions of n-butylamine and 1,2-ethanedithiol, a metal thiolate species is formed, and that this metal thiolate can be modified by isolation from the thiol-containing solvent via precipitation. As the quantity of selenium in the ink increases, the thiol content in the complex decreases, eventually producing soluble [InSex]- species. Extending this method to be used with copper selenide as a copper source, molecular precursor inks can be made for solution-processed, sulfur-free CuInSe2 films. We then show that these CuInSe2 precursor films can be fully coarsened without a fine-grain layer formation, even at the desired thicknesses of 2 μm and greater.

Optical and electrical properties of thin films of MnS/metal/MnS for photocatalysis and gas sensing applications

Thin films of manganese sulfide (MnS) with interlayers of silver and copper were prepared using the thermal evaporation technique for applications in photocatalysis and gas sensing. The structure, morphology, optical, and electrical properties of the deposited films were described by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), UV/VIS/NIR spectrophotometer, and two-probe technique. Various parameters such as crystallite size, micro-deformation, dislocation density, optical energy gap, refractive index, extinction coefficient, Urbach energy, dielectric constants, dispersion parameters, activation energy, mobility and, Seebeck coefficient were determined. According to the experimental results, XRD analysis revealed that the MnS powder has a crystalline structure with a cubic phase. While the pure MnS thin films exhibited an amorphous structure, the addition of metals (Ag and Cu) as interlayers resulted in a distinct crystallinity. The pure MnS films had a direct optical energy gap of 3.17 eV, which changed to an indirect transition with energy gaps of 2.43 eV and 2.50 eV when Ag and Cu interlayers were added, respectively. The refractive index values and dispersion of the films depended on the type of interlayer, with all films exhibiting normal dispersion. The temperature dependence of the sheet resistance indicates a semiconducting behavior of the samples, and the addition of the interlayer metal reduced the sheet resistance. Overall, the results suggest that thin films of MnS and MnS/metal/MnS hold promise for organic photocatalysis and gas sensor applications, respectively.

Synthesis of copper sulfide (CuxS) films by one-step thermal reduction of copper formate–amine–sulfur complex pastes with low sulfur ratios

A one-step thermal-reduction method was used to synthesize copper sulfide (CuxS, x = 1–2) films using copper formate–sulfur–amine pastes with low sulfur ratios (sulfur/copper formate = 0.5–1.0). The synthesized films were mixtures of Cu + Cu2S, Cu2S + Cu1.8S, or Cu1.8S + CuS, depending on the sulfur ratio. Cu1.8S alone films were synthesized from the paste with a sulfur ratio of 0.75 at 200 °C. The films comprised single-crystal nanoparticles with a size of 10–20 nm, which were covered with excess sulfur and agglomerated to form pillar-like structures. The amount of excess sulfur increased with an increasing sulfur ratio in the paste. The formation of pillar-like structures was due to the individual nanoparticles being connected by excess sulfur and the evaporation of CO2, H2O, and amine during the thermal reduction of copper formate.

Comparison of the aggressiveness of hydrogen sulfide media to steel in the vapor and water phases

Corrosion resistance in hydrogen sulfide-containing environments of the main structural steels used in infrastructure facilities of gas fields has been studied. Gas objects are distinguished by the fact that most of the internal space of equipment and pipelines is in contact with the vapor phase, the internal corrosion of which under hydrogen sulfide conditions has been little studied. The corrosion rates and the composition of the formed corrosion products, which differ depending on the type of medium (water or steam), are determined. The phase composition (crystalline or X-ray amorphous) of the resulting products affects their protective ability and differs in the vapor and aqueous phases. It has been established that under gaseous conditions of moisture condensation, local pitting lesions are formed under fragile corrosion products. The thickness of the iron sulfide film in the vapor phase turned out to be lower than in the aqueous medium. It was revealed that dangerous corrosion consequences (in the form of blisters and cracking) appear on the studied samples of carbon and low-alloy steels, which are characteristic of the process of hydrogenation under conditions of hydrogen sulfide corrosion.

The Role of Nickel in Low Alloy Steels Exposed to H2S-Containing Environments. Part I: Trench Formation at the Open-Circuit Potential

The nickel content in low alloy steels (LAS) for oil and gas exploration and production is limited to a maximum of 1 wt% according to ANSI/NACE MR 0175/ ISO 15156. This restriction is imposed to avoid sulfide stress cracking (SSC) in sour (H2S-containing) environments. In this work, the effect of Ni on the SSC of LAS was studied independently of other alloying elements. For this purpose, quenched and tempered steels heat treated to a yield strength of 610 MPa with a Ni content below and above the 1 wt% threshold were evaluated at the open-circuit potential (OCP) in unstressed specimens, and in slow strain rate tests at room temperature. Thiosulfate was used as a surrogate of H2S, according to the Tsujikawa method. It is concluded that Ni contributes to the stabilization of the sulfide films that form on the steel’s surface at OCP. The rupture of this film due to tensile stress promotes the nucleation of deep planar features, referred to as trenches, which can act as sulfide stress crack initiators. Trenches were observed exclusively in stressed, Ni-containing specimens. Moreover, trenches’ morphology, dimensions, and distribution varied with the Ni content in the steels. For the steels studied in this work, the Ni effect on trenching persisted below the 1 wt% threshold.

Microscale exploration of the sulfidization flotation theory in malachite

With the gradual depletion of copper sulfide resources, efficient flotation technologies for the recovery of copper oxide minerals, such as malachite, have received significant attention. Although sulfidization plays a critical role in malachite flotation, the fundamental theory of sulfidization flotation remains uncertain in the context of practical industrial applications. In this study, evolution of the sulfide product morphology on the malachite surface was observed after treatment with various concentrations of sodium sulfide. In addition, the valence states and phase compositions of the sulfide products were investigated using different X-ray techniques. Furthermore, the evolution of the malachite surface morphology after the formation of a sulfide film was investigated, as were the interaction forces between the malachite and bubbles under the action of butyl xanthate. As a result, it was possible to directly observe the growth process of the sulfide film on the malachite surface, and the presence of Cu(I) was confirmed in the sulfide products. Moreover, the compositions of the sulfide products were investigated using X-ray techniques. The obtained results demonstrated that the sulfide film facilitated the formation of butyl xanthate product layers on the malachite surface, whilst also enhancing the interfacial interaction forces between the malachite and the bubbles.

Investigation of the structural, optical and thermoelectric performances of flash-evaporated cobalt-doped copper sulfide thin films

In this study, we employed the flash evaporation method to deposit thin films of pure copper sulfide and cobalt-doped copper sulfide. We focused on evaluating the influence of cobalt content, ranging from zero to 9%, on the structural, optical, electrical, and thermoelectric characteristics of the synthesized thin films. Our findings indicate that the passage from the copper-rich (covellite phase to the digenite or djurleite phases) can be carried out by annealing or by doping. Raman's investigation supports the discovered phase and shows that the A1g(LO) mode intensity drops with doping. The gap energy was found to decrease by increasing the percentage of cobalt. The annealing at 350 °C resulted in good thermoelectric properties, while the dominance of the djurleite phase, resulted in the highest Seebeck coefficients.

Ultrasonic Spray Deposited CdS-GO Composite Films for Solar Cell Applications

In the present study, the synthesis and characterization of cadmium sulfide (CdS) and graphene oxide (GO) composite films are investigated. These films have the potential to be utilized in solar cell applications due to their unique optical and electric properties. A chemical bath deposition was used to prepare the CdS thin films, while the hammer method was used to synthesize GO sheets. In this comparative study, spray deposition was used to prepare CdS-GO composite films with different ratios of CdS to GO. The spray deposition method used in this study offers a simple and cost-effective way to prepare large-area films for practical applications. The structural, and optical, properties of the composite films were characterized using X-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy measurements. The results show that the CdS-GO composite films exhibit enhanced optical properties as compared to the pure CdS films. The band gap energy of the composite films decreased with increasing GO content, indicating improved optical properties. These findings suggest that CdS-GO composite films have the potential for use in solar cell applications. I-V characteristics were obtained using a solar cell tester kit to analyse the applications of fabricated conducting films in the field of solar cells.

Gas Discharge Source of Synchronous Flows of UV Radiation and Silver Sulphide Microstructures

The results of the study of the characteristics of a pulsed source of time-synchronous UV radiation streams of silver atoms and ions and micro-nanostructures of silver sulfide are given. An overvoltage nanosecond discharge was ignited in nitrogen between electrodes made of silver sulfide (Ag2S) at a distance between electrodes of 2 mm. Silver sulfide vapors were introduced into the gas-vapor mixture "Nitrogen - Ag2S" due to the ectonic mechanism. The voltage and current pulses, the pulsed power of the discharge, the energy contribution to the plasma for one pulse at pulse repetition frequencies of 40-1000 Hz were studied. The spectral characteristics of the discharge and the spatial characteristics of the microstructures deposited from the discharge plasma on a quartz substrate installed near the electrode system were studied.
 The discharge can be used as a source of bactericidal radiation and a source of microstructures based on silver sulfide, as well as a plasma chemical reactor for the synthesis of thin microstructured films of silver sulfide.

Influence of magnetic stirrer speed on the properties of chemical bath deposited FeSxOy thin films

Iron sulfide has a high potential to replace existing solar cell materials due to its cost-effectiveness and non-toxic. Nonetheless, the reported efficiency is still low, attributed to quality issues of interface/bulk single film. Thus, it is essential to overcome those quality issues by focusing on material synthesis. To date, no reported works on the effects of magnetic stirrer speed in the chemical bath deposition (CBD) of iron sulfide film. Hence, this work elucidates the influence of magnetic stirrer speed (100–700 revolutions per minute-RPM) in the CBD on the properties of iron sulfide (iron-sulfide-oxide: FeSxOy) films. The magnetic stirrer speed was limited to below 1000 RPM because the high stirring speed contributed to weak molecule interaction between the FeSxOy cluster and the grown FeSxOy film. As a result, the solution's fast motion could easily break the molecule interaction between them (poor film adherence). The Scanning Electron Microscopy (SEM)-Energy Dispersive X-Ray Spectroscopy (EDX) showed the number/size of agglomerations relatively increased (reduction in uniformity) and the oxygen increased/sulfur decreased with an increase in the speed. The X-ray diffraction (XRD) patterns revealed that the pyrite transformed to goethite/hematite at a magnetic stirrer speed > 300 RPM. The film with 100 RPM produced a larger crystallite size. The Raman spectra exhibited no FeSxOy and pyrite phases for the film deposited at 700 RPM. The Hall Effect displayed that film at 100 RPM yields the highest carrier density of electrons (n-type). Films with 100 and 300 RPM showed absorption edges at a wavelength of around 400 nm, and their estimated bandgaps via the Tauc plot are 3.35–3.44 eV. Furthermore, a film with 100 RPM showed better quality and was suitable to be applied as a window layer (n-type) in thin film solar cells.

Chemical vapor reaction synthesis and photoelectronic properties of CuS and Cu3SbS4 thin films

Chemical vapor reaction is a simple and efficient experimental means of preparing metal sulphide films. Through systematically studying the effect of vulcanisation temperature on the growth of copper sulfide (CuS) thin film. The copper antimony sulfide (Cu3SbS4) thin film was obtained by further vulcanized Sb/Cu mental film. The structure and optical properties of the as-prepared films were characterized by x-ray diffraction, Raman and photoluminescence spectra. The hexagonal structure of CuS film was confirmed and Cu3SbS4 grew preferentially along the (112) crystal plane. The surface grains of CuS and Cu3SbS4 films were finally condensed into spheres. The content of S and the resistance of the films increase with the increase in temperature, but the bandgap of the films will be decreased. The bandgap of Cu2−xS films prepared at 195 °C−350 °C is in the range of 2.2–2.5 eV and that of Cu3SbS4 thin films prepared at 350 °C is 1.77 eV, and has good absorption in the visible light range. In addition, The Hall effect measurement indicated CuS and Cu3SbS4 films have p-type semiconducting behavior. The carrier concentration and mobility are 2.45 × 1021 cm−3 and 1.28 cm2 Vs−1 for CuS, and 4.30 × 1017 cm−3 and 185.93 cm2 Vs−1 for Cu3SbS4, respectively. The I-T tests show that the CuS and Cu3SbS4 thin films have photoconductive properties.

Mass spectrometry of complex compound of bis-thiourea-lead (II) chloride

Complex compounds of lead salts and thiourea are of interest due to the possibility of their practical application as precursors in the deposition of metal sulphide films. It is relevant to establish the relationship between the composition and structure of the initial complex compounds and the structure of the sulphides formed as a result of their thermal destruction. This paper presents the results of studying the complex compounds formed in an aqueous solution of lead chloride and thiourea. The structure of the complex compounds was determined by matrix-assisted laser desorption/ionisation mass spectrometry. The mass spectrometry data confirmed the formation of the [Pb((NH2)2CS)2Cl2] complex in the solution, which is a precursor in the deposition of PbS films. It was demonstrated that mass spectrometry fragmentation of the molecular ion of the [Pb((NH2)2CS)2Cl2] compound leads to the formation of a lead sulphide ion. The obtained data confirm the formation of the lead-sulphur bonds in the inner sphere of the complex compound, which are fragments of the crystal structure of the prospective sulphide formed during the thermolysis of the complex.

Exploration of impact of thermal condition on microstructural-optical- electrical properties of Ni doped CdS thin films

In this study, Ni-doped cadmium sulfide films were deposited onto ITO substrate using spray-pyrolysis. The effects of annealing(450 °C) on the opto-electrical properties of deposited thin films were investigated.The band gap of films was estimated using absorption spectroscopy, and it decreased from 2.88 eV and 2.81 eV with annealing. The effect of annealing on refractive index and crystal size was also studied. Additionally,the dispersion of refractive index is calculated in terms of Wemple-DiDomenico approch. Third order susceptibility and nonlinear refractive index are calculated of Ni doped CdS films.The electrical properties of the films were characterized using the four-probe method, and the conductivity was found to increase with annealing temperature. The fabricated Ag/Ni:CdS/ITO Schottky diode was tested under illumination conditions, and the empirical diode parameters were influenced by annealing temperature. The morphological and elemental composition analysis of the Ni-doped CdS films was carried out using FESEM and EDS analysis.

Investigation of 1-octanethiol capped ZnS nanoparticles as lubricant additives and tribological behavior of oil-based nanolubricant

1-Octanethiol (OT) capped ZnS nanoparticles (OT-ZnS) as lubricating oil additives were investigated by tribological tests including wear tests and rheological measurements. The wear tests were performed on lubrication states using a custom design wear test device consisting of a rotating pin on a cylinder geometry. A rotating 1.2379 cylinder (steel counterpart) and a stationary C40 pin were used as a pair of test material for the wear test. The stationary pin was pressed against a rotating cylinder under lubrication conditions. It was observed that the synthesized OT-ZnS NP effectively improved the lubrication performance of 10W engine oil and the surface properties of the test materials. The addition of OT-ZnS NPs to the 10W base oil increased its viscosity and decreased the contact angle (CA) values. The results showed that the wear loss and the wear scar dimensions were both the lowest, while 0.0125 (wt.%) of OT-ZnS NPs were treated with the base oil. The mass loss of the pins was reduced to more than 6.3%. The wear reduction was observed at about 27% and the length of wear scar in the minor axis was reduced to 11.4% when a load of 100 kg was applied. The images of wear scars showed that the OT-ZnS NPs additives could prevent severe contact with the interacting surfaces. OT-ZnS NPs partially filled on the grooves and adhered on the wear scar surfaces and promote tribofilm formation, thereby it improve the tribological performance of 10W base oil, especially under extreme pressure conditions. Sulfide film (sulfuration layer) adhered to the wear scar surfaces and decrease the wear.

Hierarchical Surface Structures and Large-Area Nanoscale Gratings in As2S3 and As2Se3 Films Irradiated with Femtosecond Laser Pulses.

Chalcogenide vitreous semiconductors (ChVSs) find application in rewritable optical memory storage and optically switchable infrared photonic devices due to the possibility of fast and reversible phase transitions, as well as high refractive index and transmission in the near- and mid-infrared spectral range. Formed on such materials, laser-induced periodic surface structures (LIPSSs), open wide prospects for increasing information storage capacity and create polarization-sensitive optical elements of infrared photonics. In the present work, a possibility to produce LIPSSs under femtosecond laser irradiation (pulse duration 300 fs, wavelength 515 nm, repetition rate up to 2 kHz, pulse energy ranged 0.03 to 0.5 μJ) is demonstrated on a large (up to 5 × 5 mm2) area of arsenic sulfide (As2S3) and arsenic selenide (As2Se3) ChVS films. Scanning electron and atomic force microscopy revealed that LIPSSs with various periods (170-490 nm) and orientations can coexist within the same irradiated region as a hierarchical structure, resulting from the interference of various plasmon polariton modes generated under intense photoexcitation of nonequilibrium carriers within the film. The depth of the structures varied from 30 to 100 nm. The periods and orientations of the formed LIPSSs were numerically simulated using the Sipe-Drude approach. A good agreement of the calculations with the experimental data was achieved.

Green synthesis of tin sulfide films for potential applications in supercapacitors and the effect of annealing

Tin sulfide has been widely studied as electrode materials for supercapacitors owing to their high theoretical pseudocapacitance. This paper reports a novel green synthesis of tin sulfide nanoparticles as a substrate using FTO glass slides. Moreover, the material characterization with respect to the morphology (scanning electron microscopy), phase composition (X-ray diffraction), crystallinity and molecular interactions (Raman spectroscopy) and electric (electrochemical performance) properties were provided. After annealing at 300 °C, smooth and well-adhered tin sulfide films were formed, consisting of smaller spherical particles 28–37 nm in size, and the thickness of annealed films is in the interval of 230–280 nm, depending on the number of tin sulfide synthesis cycles and the amount of complexing agent. According to Raman spectroscopy results, annealed films consist of SnS with secondary SnS2 or Sn2S3 phase. The obtained material was used for electrochemical calculations for supercapacitor application, and a significant increase of energetic values was seen after the annealing of films. The highest values of energetic parameters during this work have been provided by tin sulfide film synthesized with 1.0 g of L-ascorbic acid using 20 SILAR cycles.

The effects of chloride and sulphate on the growth of sulphide films on copper in anoxic sulphide solutions

AbstractThe corrosion of copper in chloride‐ and sulphate‐containing solutions containing sulphide (ranging from 5 × 10−5 M to 10−3 M) was studied by electrochemical impedance spectroscopy and the structure and physical properties of the copper sulphide deposits (Cu2S) were analysed by scanning electron microscopy. At low [SH−], a porous and non‐protective deposit was formed, and the low corrosion rates were limited by sulphide transport, partially within the deposit and partially in the bulk of the solution. At higher [SH−], the corrosion rates were much higher and initially more rapid in chloride‐containing than in sulphate‐containing solutions, suggesting a direct role for chloride in the interfacial corrosion process. When the copper sulphide deposit thickened, the rate became limited by CuI transport within the more compact and more crystalline deposit formed. Changes in the morphology of the deposit suggest that chloride adsorption on the surfaces of the deposit inhibited the incorporation of Cu3S3 clusters, transported from the corroding copper surface, into the growing crystals.

Effect of preoxidation on copper flotation from copper-lead mixed concentrate

Flotation separation of galena and chalcopyrite is always a difficult problem in mineral processing. In this paper, the selective preoxidation of galena and chalcopyrite with sulfuric acid was developed, and then the two minerals were completely separated by flotation. The surface oxidation mechanism of galena and chalcopyrite with sulfuric acid was analyzed by Fourier transform infrared spectroscopy (FT-IR) and Atomic Force Microscopy (AFM), and the results showed that hydrophilic oxide film was formed on the galena surface, while the surface of chalcopyrite is still hydrophobic sulfide film, which led to the separation of the two minerals by flotation. In addition, the Response Surface Methodology (RSM) was used to analyze the influence of main preoxidation parameters on the flotation separation of copper-lead concentrate, and the parameters were further optimized, as follows: sulfuric acid concentration of 5.3 mol/L, oxidation temperature of 101.8 °C and time of 48.3 min. The mixed concentrate containing Cu 11.57% and Pb 16.75% was preoxidized under the above conditions, and the flotation separation verification results showed that Cu concentrate with Cu grade of 18.09% and recovery of 95.41%, and Pb concentrate with Pb grade of 44.96% and recovery of 95.94% was obtained respectively. This paper provides a new method of preoxidation combined flotation to achieve high-efficiency separation of copper-lead mixed concentrate.