Comparison of the efficacy of sulfurization agents in decreasing the sheet resistance of polyamide and polyethylene with copper sulfide layers and influence of their compositions

The process of obtaining semiconductive and electrical conductive layers of copper sulfides by the sorption — diffusion method on polymers (polyamide 6 and low density polyethylene) using solutions of potassium pentathionate, K₂S₅O₆, and higher polythionic acids, H₂S _n O₆ (n = 21, 33), was investigated. The layers were characterized for compositional and electrical properties by X-ray diffraction (XRD) analysis and sheet resistance measurements. The thickness of copper sulfides layers on polyamide and polyethylene increased with increasing time of polymer sulfurization and varied from 10 to 43 μm. The variations of the sheet resistance of copper sulfides layers formed on the surface of polymers on sulfurization agent used, the conditions of sulfurization, chemical and phase composition of the obtained layers were established. Sheet resistance of copper sulfides layers decreases with increasing time of the duration of sulfurization and the number of sulfur atoms in the polythionate anion. The sheet resistance values for copper sulfide layers formed on the polyamide surface are much lower than those of Cu _x S formed on the polyethylene surface. XRD showed the predomination of Cu _x S phases with low x values.      

The influence of process conditions on the formation of thallium sulfide layers on polyethylene by the use of higher polythionic acid H2S33O6

Thallium sulfide layers of varying composition form on the surface of low-density polyethylene (PE) when the PE films have been sulfurized in a solution of higher polythionic acid H₂S₃₃O₆, and then immersed in the alkaline solution of thallium (I) sulfate. The concentration of sulfur sorbed-diffused into PE surface increases with the increase of the sulfurization time and concentration of higher polythionic acid solution. The concentration of thallium in the Tl _x S _y layers depends on the sulfur concentration sorbed-diffused into PE, the concentration, and temperature of thallium (I) sulfate solutions. By chemical analysis of the obtained sulfide layers it was determined that the values of x and y in the Tl_xS_y layers varies in the intervals: 1<x<3, 1<y<6. Two phases TlS, Tl₂S₂ were identified by X-ray diffraction analysis in thallium sulfide layers. Scanning Electron (SEM) and Atomic Force (AFM) microscopies were used to characterize surface morphology of thallium sulfide layers. The films deposited on the PE surface have a non-homogeneous structure, and consist of separated islands.      

Zeolite ZSM-5 containing copper ions: The effect of the copper salt anion and NH<Subscript>4</Subscript>OH/Cu<Superscript>2+</Superscript> ratio on the state of the copper ions and on the reactivity of the zeolite in DeNO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

Isotherms of copper cation sorption by H-ZSM-5 zeolite from aqueous and aqueous ammonia solutions of copper acetate, chloride, nitrate, and sulfate are considered in terms of Langmuir’s monomolecular adsorption model. Using UV-Vis diffuse reflectance spectroscopy, IR spectroscopy, and temperatureprogrammed reduction with hydrogen and carbon monoxide, it has been demonstrated that the electronic state of the copper ions is determined by the ion exchange and heat treatment conditions. The state of the copper ions has an effect on the redox properties and reactivity of the Cu-ZSM-5 catalysts in the selective catalytic reduction (SCR) of NO with propane and in N₂O decomposition. The amount of Cu²⁺ that is sorbed by zeolite H-ZSM-5 from aqueous solution and is stabilized as isolated Cu²⁺ cations in cationexchange sites of the zeolite depends largely on the copper salt anion. The quantity of Cu(II) cations sorbed from aqueous solutions of copper salts of strong acids is smaller than the quantity of the same cations sorbed from the copper acetate solution. When copper chloride or sulfate is used, the zeolite is modified by the chloride or sulfate anion. Because of the presence of these anions, the redox properties and nitrogen oxides removal (DeNO _x ) efficiency of the Cu-ZSM-5 catalysts prepared using the copper salts of strong acids are worse than the same characteristics of the sample prepared using the copper acetate solution. The addition of ammonia to the aqueous solutions of copper salts diminishes the copper salt anion effect on the amount of Cu(II) sorbed from these solutions and hampers the nonspecific sorption of anions on the zeolite surface. As a consequence, the redox and DeNO _x properties of Cu-ZSM-5 depend considerably on the NH₄OH/Cu²⁺ ratio in the solution used in ion exchange. The aqueous ammonia solutions of the copper salts with NH₄OH/Cu²⁺ = 6–10 stabilize, in the Cu-ZSM-5 structure, Cu²⁺ ions bonded with extraframework oxygen, which are more active in DeNO _x than isolated Cu²⁺ ions (which form at NH4OH/Cu2+ = 30) or nanosized CuO particles (which form at NH₄OH/Cu²⁺ = 3).     

Formation and study of mixed copper sulfide-copper telluride layers on the surface of polyamide 6

The layers of mixed copper chalcogenides, Cu_xS-Cu_yTe, were formed on the surface of polyamide using solutions of potassium and sodium telluropentathionates, K₂TeS₄O₆ and Na₂TeS₄O₆, respectively, and of telluropentathionic acid, H₂TeS₄O₆, as precursors of chalcogens. The concentration of sorbed chalcogens increased with the increasing time of the treatment, concentration and temperature of precursor solution. Cu_xS-Cu_yTe layers are formed on the surface of polyamide after the treatment of chalcogenized polymer with Cu(II/I) salt solution. The concentration of copper in the layer increases with the increase of chalcogenization duration, concentration and the temperature of chalcogenization solution. In the surface of Cu_xS-Cu_yTe layers various copper, sulfur, tellurium and oxygen compounds (Cu₂S, CuS, S₈, Cu_xS, Cu_yTe, Cu(OH)₂ and TeO₂) were present. Chalcogenides were the major components in the layer. Chalcogenide phases — digenite, Cu_1.8S, djurleite, Cu_1.9375S, anilite, Cu₇S₄, geerite, CuS₂, chalcocite, Cu₂S, tetragonal Cu_3.18Te₂, Cu_2.72Te, hexagonal Cu₂Te, Cu₄Te₃, Cu_1.80Te, Cu_1.85Te₂, and orthorhombic vulcanite, CuTe were identified in the layers by X-ray diffraction. Electrical sheet resistance of Cu_xS-Cu_yTe layers vary from ∼ 1.0 kW cm⁻² to 4×10³ kΩ cm⁻². It is concluded that the formation of chalcogenide layers proceeds in the form of islands which grow into larger agglomerates. Use of the gathered data enables design and formation of the Cu_xS-Cu_yTe layers with desired conductivities.      

Deposition of Cu on a polycrystalline Pt-electrode at potentials more positive than the equilibrium potential from CuSO<Subscript>4</Subscript> solutions of various acidities in the presence of H<Subscript>2</Subscript>SeO<Subscript>3</Subscript>

Undervoltage deposition of copper adatom layers on Pt was studied in acid CuSO₄ solutions at various pH values with or without addition of H₂SeO₃.     

Investigation of the interaction between Co sulfide coatings and Cu(I) ions by cyclic voltammetry and XPS

The interaction between the Co sulfide coating formed on a glassy carbon electrode and Cu(I)-ammonia complexes solution was investigated by cyclic voltammetry in 0.1 M KClO₄, 0.1 M NaOH and 0.05 M H₂SO₄ solutions. It was determined that, after treating the cobalt sulfide coating formed by two deposition cycles with Cu(I)-ammonia complexes (0.4 M, pH 8.8–9.0, τ=180 s, T=25±1°C), an exchange occurs between the coating components and Cu(I). Copper(I) substitutes 75% of the Co(III) compounds present in the coating (~1.81×10^–7 mol cm^–2) because of Cu₂O (1.36×10^–7 mol cm^–2) formation. The rest of the Co(II) and Co(III) sulfide compounds are also replaced by copper with formation of Cu_{2– x} S with a stoichiometric coefficient close to 2 (~1.9). After modifying the cobalt sulfide coatings with Cu(I) ions, the total amount of metal (Co+Cu) increases, owing to the sorption of Cu(I) compounds. In addition, the number of deposition cycles decreases from 3 to 1.5 [1 cycle involves cobalt sulfide layer formation and 0.5 cycle is attributed to modifying by Cu(I) ions]. The coatings modified in the above-mentioned manner may be successfully used for plastic electrochemical metallization as Cu_{2– x} S coatings formed by three deposition cycles. Electronic Publication     

The formation of MoS<Subscript>2</Subscript> secondary phase at the Cu—Zn—Sn—S/Mo interface during the sulfurization process of Cu—Zn—Sn precursor films

We report on the influence of the sulfurization conditions on the MoS₂ secondary phase formation in Cu—Zn—Sn—S thin films synthesized by thermal evaporation method of metals and intermetallics that can be used for the formation of absorbing layers of solar cells. The dependence between photoconductivity and the intensity of the base line of MoS₂ was found in Raman spectra, which is described by a curve with characteristic maximum. It was found that the secondary phase formation on the Cu—Zn—Sn—S/Mo boundary and photoconductivity of sulfurized films are strongly dependent on the applied temperature conditions. Specifically, films without MoS₂ phase have a low photoconductivity, whereas a high photoconductivity was observed for the films with significant content of secondary phase.     

Preparation of Cu<Subscript>2</Subscript>O/AC photocatalysts and their photocatalytic activity in degradation of pyrocatechol

Cu₂O on active carbon (Cu₂O/AC) catalysts were prepared by impregnation of support with aqueous solutions of CuSO₄ in various concentrations and then treated with a mixture of glucose and NaOH. Photocatalytic activity of the prepared catalysts was investigated in the photocatalytic degradation of pyrocatechol. The catalyst prepared by dipping of 0.5 g of AC into 25 ml of 0.04 mol/l CuSO₄ was found to exhibit the best activity. The effects of the reaction time and the amount of catalyst on the photocatalytic degradation of pyrocatechol were also studied.     

SXPS analysis of passivation and complexation on the CdS (101¯ 0) surface

CdS(101ˉ 0) surfaces were chemically modified by oxidation in air or UV/ozone, sulfurization after treatment with a Br₂-methanol solution and reaction with the multidendate organic reactant 2-mercaptobenzothiazole (MBT). Surface sensitive photoelectron spectra from tuned excitation using synchrotron radiation (SXPS) show that initial oxidation by air gives monolayer coverages of sulfate (with minor contributions of sulfite) and chemisorbed polysulfur species passivating the surface. In contrast to this behavior the oxidation by UV/ozone proceeds very fast, giving thick sulfate layers. Thick layers of elemental sulfur are created during Br₂-methanol treatment. SXPS results show that a monolayer of chemisorbed polysulfide between the sulfur coverage and the sulfide is only removed by annealing the substrate up to 500 K. The reaction of MBT with the CdS surface is photochemically activated giving a submonolayer of MBT/adsorbate complex covered by bis(2-benzothiazolyl)disulfide (BBTD). A scheme of the photoinduced oxidation mechanism creating the disulfide is proposed. Received: 30 July 1997 / Accepted: 23 January 1998     

Modification of molybdenum disulfide (2H-MoS<Subscript>2</Subscript>) and synthesis of its intercalation compounds

We have shown that powdered molybdenum disulfide prepared as a result of the exfoliation (singlelayer dispersion) of a crystalline precursor (2H-MoS₂) and subsequent precipitation in an acid medium, is capable of forming intercalation compounds in reacting with salts of copper and tetramethylammonium, as well as diethylamine and triethylamine. We consider factors influencing the composition and type of the alternation of guest and host layers in the resulting layered compounds. Relationships between charge transfer to MoS₂ layers and the extraordinary reactivity of its modified species are discussed.     

纳米硫化铜颗粒自组装为球、空心球和线形结构

用水和乙二醇混合物为溶剂,应用溶剂热合成方法制备了由纳米颗粒自组装的球、空心球和线形结构的铜的硫化物,如 Cu7S4, Cu1.8S, Cu1.81S 和 Cu2S。 考查了溶剂组成（水含量的变化）、反应时间、实验温度的变化对所制备样品的形貌和物相结构的影响。研究了其形成机理。结果表明,随着反应时间的变化,首先形成纳米颗粒的铜的硫化物。通过自组装形成线形结构。最后转化为球形或空心球形结构。     

A thermoanalytical study of the oxidation of chalcocite

A sample of chalcocite of particle size 45–75 μm, has been oxidised in a TG-DTA apparatus at a heating rate of 10 deg·min⁻¹ and the products at various temperatures characterised by XRD, SEM, FTIR and EPMA. This has enabled the events in the TG-DTA record to be assigned to specific chemical reactions, as well as the development of a full reaction scheme for the oxidation of chalcocite. Only minor reactions occurred up to 430°C, but above this temperature there was significant oxidation which resulted in an exotherm and mass gain. These events were due primarily to the oxidation of sulfide to copper(I) oxide, and the formation of copper(II) sulfate. The reaction then slowed, but melting commenced at 490°C which permitted further oxidation to take place with the appearance of a second exotherm and mass gain. By 570°C, sulfide oxidation was complete, but solid-solid reactions took place between Cu₂O and CuSO₄ to produce CuO·CuSO₄. Some conversion of Cu₂O had occurred. By 775°C, CuO and CuO·CuSO₄ were the only phases detected. Above this temperature the latter phase was unstable and decomposed to the end product CuO. In celebration of the 60^th birthday of Dr. Andrew K. Galwey     

Sulfurization of polymers

Polydiethylsiloxane reacts with elemental sulfur at 300–320 °C (ZnCl₂ slightly accelerates the process) with evolution of hydrogen sulfide and formation of black lustrous paramagnetic powders (sulfur content up to 38.50%), which possess a noticeable electric conductivity (3.20·10⁻⁷ S cm⁻¹ when doped with I₂) and redox properties. Polydimethylsiloxanes are stable under the same conditions. In rechargeable lithium batteries, the sulfurized polydiethylsiloxane behaves as an active cathode material allowing charging and discharging of the battery. The specific capacities of the cathodic and anodic processes (80–100 (mA h) g⁻¹) change insignificantly. The hydrolytic stability, elemental analysis, IR and ESR spectra, DSC-TGA and derivatographic analyses data, the electric conductivity, and the character of the electrochemical activity of the polymers synthesized indicate that the polymers contain the polyvinylene disulfide blocks cross-linked by the polysiloxane chain.     

Thermodynamic study of Cu-Tl-Te system using EMF technique with Cu<Subscript>4</Subscript>RbCl<Subscript>3</Subscript>I<Subscript>2</Subscript> solid electrolyte

The EMF method with a solid Cu⁺-conducting electrolyte of Cu₄RbCl₃I₂ was sued to study the Cu-Tl-Te system in the temperature range of 300–420 K. A diagram of solid-phase equilibriums of this system is constructed, partial molar functions of copper in alloys, standard thermodynamic functions of formation and standard entropies of CuTlTe₂, CuTl₄Te₃, Cu₂TlTe₂, Cu₃TlTe₂, Cu₉TlTe₅ triple compounds and Cu _x Tl_{5 − x} Te₃ solid solutions (0 < x < 1) are calculated. The obtained results confirmed the assumption as to the possibility of using this modification for the EMF technique for thermodynamic studies of copper-containing triple systems, even if they contain a less noble component than copper.     

Transition metal salts of H<Subscript>4</Subscript>PMo<Subscript>11</Subscript>VO<Subscript>40</Subscript> for efficient H<Subscript>2</Subscript>S removal in the liquid redox process

Several transition metal (Cu²⁺, Fe³⁺, Zn²⁺, Mn⁴⁺, and Cr⁶⁺) salts of H₄PMo₁₁VO₄₀ were prepared and their solutions were used initially for H₂S removal in the liquid redox process. H₂S removal tests were performed by dynamic absorption experiments. Among these polyoxometalates, that with the Cu²⁺ cation was found to have pronounced H₂S removal performance with the removal efficiency of up to 98%. The relevant oxidative desulfurization mechanism and the role of Cu²⁺ were studied.     

Refinement of the crystal structure of as-schwatzite Cu<Subscript>6</Subscript>(Cu<Subscript>5.26</Subscript>Hg<Subscript>0.75</Subscript>)(As<Subscript>2.83</Subscript>Sb<Subscript>1.17</Subscript>)S<Subscript>13</Subscript> (Aktash,Altai mountaines)

The crystal structure of As-schwatzite Cu₆(Cu_5.26Hg_0.75)(As_2.83Sb_1.17)S13 (Aktash deposit, Altai mountains) is refined. Tetrahedrally shaped dark-gray single crystals of the mineral belong to the cubic crystal system: I4¯3m space group, a = 10.2890(1) Å, V = 1089.2(1) ų, d = 4.99 g/cm³, Z = 2 for the composition Cu_11.26Hg_0.75As_2.83Sb_1.17S₁₃, R = 0.0177. The structure is based on the sphalerite-like framework comprising identically oriented (Cu,Hg)S₄ tetrahedra ((Cu,Hg)-S 2.3452(8) Å) and (As,Sb)S₃ pyramids ((As,Sb)-S 2.311(1) Å) sharing their vertices. The centers of [Cu₆] octahedra in the (000) and (1/2 1/2 1/2) positions coinciding with the centers of the “cluster” anionic vacancies [□]₄ are occupied by the so-called “thirteenth” sulfur atom. Quantum chemical calculations of the electron density are carried out for the [As₄S₁₃Cu₆]⁶ fragment. The calculation results confirm the presence of strain in the [As₄S₁₃Cu₆]⁶ moiety, which exists due to the support of the surrounding symmetric framework including the external sulfur atoms of the fragment. The possibility of inclusion of mercury into the framework, which is much richer in arsenic than in antimony, is demonstrated. High stability of the framework determines significant compression of the S-centered [SCu₆] octahedron in its interstices, bringing together copper atoms to 3.145(1) Å and shortening the Cu-S distances to 2.224(1) Å     

纳米碳管电极的制备与电化学检测性能研究

纳米碳管由于其独特的物理和化学性能及广阔的应用前景而备受关注,其相关研究涉及到众多领域[1￣3]。在电化学分析领域,与其它碳电极材料相比,纳米碳管电极具有较大的电极表面积和较高的电子传递速率,其使用能增大响应电流、降低检出限,是目前电化学分析电极中一个十分引人注目     

A Four‐Electron Sulfur Electrode Hosting a Cu2+/Cu+ Redox Charge Carrier

The elemental sulfur electrode with Cu²⁺ as the charge carrier gives a four‐electron sulfur electrode reaction through the sequential conversion of S?CuS?Cu₂S. The Cu‐S redox‐ion electrode delivers a high specific capacity of 3044 mAh g^?1 based on the sulfur mass or 609 mAh g^?1 based on the mass of Cu₂S, the completely discharged product, and displays an unprecedently high potential of sulfur/metal sulfide reduction at 0.5 V vs. SHE. The Cu‐S electrode also exhibits an extremely low extent of polarization of 0.05 V and an outstanding cycle number of 1200 cycles retaining 72 % of the initial capacity at 12.5 A g^?1. The remarkable utility of this Cu‐S cathode is further demonstrated in a hybrid cell that employs an Zn metal anode and an anion‐exchange membrane as the separator, which yields an average cell discharge voltage of 1.15 V, the half‐cell specific energy of 547 Wh kg^?1 based on the mass of the Cu₂S/carbon composite cathode, and stable cycling over 110 cycles.     

Activity of cobalt sulfide catalysts in the hydrogenolysis of dimethyl disulfide to methanethiol: Effects of the nature of a support and the procedure of supporting a cobalt precursor

The conversion of dimethyl disulfide to methanethiol on various catalysts containing supported cobalt sulfide in an atmosphere of hydrogen was studied at atmospheric pressure and T = 190°C. On CoS introduced into the channels of zeolite HSZM-5, the process occurred at a high rate but with a low selectivity for methanethiol because the proton centers of the support participated in a side reaction with the formation of dimethyl sulfide and hydrogen sulfide. Under the action of sulfide catalysts supported onto a carbon support, aluminum oxide, silicon dioxide, and an amorphous aluminosilicate, the decomposition of dimethyl disulfide to methanethiol occurred with 95–100% selectivity. The CoS/Al₂O₃ catalysts were found to be most efficient. The specific activity of alumina-cobalt sulfide catalysts only slightly depended on the phase composition and specific surface area of Al₂O₃. The conditions of the thermal treatment and sulfurization of catalysts and, particularly, the procedure of supporting a cobalt precursor onto the support were of key importance. Catalysts prepared through the stage of supporting nanodispersed cobalt hydroxide were much more active than the catalysts based on supported cobalt salts.     

Phase transformations of CuCrS<Subscript>2</Subscript>: Structural and chemical study

The structure and composition of the CuCrS₂ powder synthesized by sulfidation of a mixture of oxides Cu₂O:Cr₂O₃ = 1:1 at 850°C and cooled to room temperature at a rate of 60°C/min were studied by X-ray powder diffraction and differentiating solution. A rhombohedral CuCrS₂ phase (space group R3m) was found, which was stoichiometric in composition and had disordering in the copper sublattice because copper was arranged at the tetrahedral and octahedral sites with occupancy 10% at the latter. The structure of CuCrS₂, in which the octahedra were occupied by copper atoms at room temperature, was found for the first time; in known structures, the copper atoms occupied only the tetrahedral sites, while the probability of octahedral occupation appeared around 400°C (order-disorder transition). The partially disordered CuCrS₂ phase is intermediate on the route to complete ordering. The quickly cooled CuCrS₂ powder is unstable; after the second heating to 500°C with prolonged annealing at 390°C→180°C→80°C→25°C, its transition to the stable state was accompanied by liberation of 2–4 wt.% Cu₉S₅. The real composition of ternary sulfide after isolation of the Cu₉S₅ phase is discussed using the data of the structural method, differential dissolution, and magnetic measurements.