Covellite CuS Research Articles

Investigations on optical properties of synthesized covellite CuS hollow nano cubic structures

In this work, hollow nanocubes of CuS were synthesized by employing a chemical route via Kirkendall effect. The influence of sulphur concentration on the optical and structural properties of CuS by varying the amount of sulphur during synthesis was investigated. The synthesized hollow cubes were characterized by using Scanning Electron microscope (SEM), X-Ray Diffraction (XRD) Analysis, Ultra Violet -Visible (UV-Vis.) Spectroscopy, Photoluminescence (PL) Spectroscopy, Raman Spectroscopy and X-ray photoelectron Spectroscopy (XPS). The formation of cubic morphology was affirmed by SEM analysis in all three samples. The length of the sidesthe of the cube lies in the range of 500-600 nm. XRD studies confirmed the formation of the pure phase of covellite CuS. Also, XPS analysis validated the presence of excess sulphur in the sample with Cu:S as 1:150 along with variation in the stoichiometric ratio of 1: 0.5. Since, this was not the case for Cu:S as 1:100, as it showed the desired stoichiometry of 1.1: 0.9 that supports the pure phase of CuS. Raman spectra further confirmed the purity of the sample. Absorption analysis revealed a well-defined bandgap with the absence of an intermediate defect state with a bandgap of 1.4 eV in the optimized sample. PL spectra displayed a decent recombination rate and minimum non-radiative losses in the 1:100 sample. These outcomes assurances the sample with Cu:S as 1:100 could be used as a potential material for solar cell applications.

Polyphosphate-Mediated Crystallographic and Colloidal Stabilization of CuS Nanoparticles: Enhanced NIR-Responsive Chemo-Photothermal Efficacy.

Photothermal therapy (PTT) is an emerging treatment modality for cancer management. However, the photothermal agents (PTAs) used in PTT should have sufficient biocompatibility, water dispersibility, and good photoresponsive. In this aspect, water-dispersible and biocompatible linear polyphosphate (LP)-functionalized CuS nanoparticles (LP-CuS NPs) were developed using sodium tripolyphosphate (LP molecule) as a surface passivating agent. The successful formation of the green covellite CuS phase was confirmed by X-ray diffraction and TEM analyses, and its surface functionalization with the LP ligand was evident from X-ray photoelectron spectroscopy, Fourier transform infrared, thermogravimetric analysis, and light scattering measurements. It has been found that the use of LP not only stabilizes the crystallographic covellite CuS phase by overcoming the requirement of a soft ligand but also provides long-term aqueous colloidal stability, which is essential for PTT applications. The aqueous suspension of LP-CuS NPs showed excellent heating efficacy under near infrared (NIR) light irradiation (980 nm) and has a strong binding affinity towards anticancer drug, doxorubicin hydrochloride (DOX). The drug-loaded systems (DOX@LP-CuS NPs) revealed a pH-dependent drug release behavior with higher concentrations in a mild acidic environment. The in vitro studies showed substantial cellular uptake of DOX-loaded systems in cancer cell lines and enhanced toxicity towards them upon irradiation of NIR light through apoptotic induction, suggesting their potential application in chemo-photothermal therapy.

CuxS films as photoelectrodes for visible-light water splitting

Copper sulfides are appealing semiconductors for optoelectronics applications requiring visible-light activity, such as solar water splitting, due to their relatively low band gaps and earth-abundance. This study investigates the effect of deposition conditions, including substrate temperature and background gas pressure, on the characteristics and photoelectrochemical performance of copper sulfide (CuxS) films grown by pulsed laser deposition (PLD) on Si (100) substrates. The results reveal that varying the deposition parameters influences the crystalline phases, morphology, and optoelectronic properties of the films. For deposition at room temperature, the films exhibited covellite CuS phase, while elevated deposition temperatures (250 °C and 500 °C) led to the formation of Cu1.8S and Cu2S phases, resulting in narrowing of the band gap, with the increased temperature also enhancing the film crystallinity and surface roughness. As a result of the changes in film morphology and crystal structure, photocurrent density magnitudes increased with higher deposition temperatures, reaching 0.747 mA/cm2 at −0.8 V for films deposited at 500 °C under vacuum, at least an order of magnitude higher than reported in comparable previous studies of the photoelectrochemical performance of CuxS. Background gas pressure only slightly affected the photocurrent density, with changes in photoactivity also correlating with changes in film roughness and band gap. The results demonstrate the good visible-light activity and behavior of CuxS as a stand-alone photoelectrode material, with tunability based on the fabrication conditions, suggesting their potential use in photoelectrochemical and other solar energy conversion applications.

Aqueous CuS nanocrystals via a flow synthesis approach

AbstractAqueous synthesis of covellite CuS nanoparticles holds significant importance in the field of nanomaterials and environmental sustainability. Using water as a solvent and reactant in the synthesis process aligns with green chemistry principles. It enhances nanoparticle production's scalability and safety. CuS nanoparticles have gained attention for their diverse applications in catalysis, energy storage, and environmental remediation. Aqueous synthesis reduces the environmental footprint associated with hazardous organic solvents, making it an eco‐friendly approach. We report on synthesis routes toward covellite CuS nanocrystals (NCs), emphasizing easy and fast synthesis techniques. Additionally, we develop a flow synthesis of small near infrared active CuS NCs in a custom‐made flow reactor. Combining the advantages of aqueous synthesis and flow chemistry yields a robust and sustainable method for producing covellite CuS NCs readily dispersible in water medium, paving the way for their widespread application in diverse fields.

Surface Structure to Tailor the Electrochemical Behavior of Mixed-Valence Copper Sulfides during Water Electrolysis.

The semiconducting behavior of mixed-valence copper sulfides arises from the pronounced covalency of Cu-S bonds and the exchange coupling between CuI and CuII centers. Although electrocatalytic study with digenite Cu9S5 and covellite CuS has been performed earlier, detailed redox chemistry and its interpretation through lattice structure analysis have never been realized. Herein, nanostructured Cu9S5 and CuS are prepared and used as electrode materials to study their electrochemistry. Powder X-ray diffraction (PXRD) and microscopic studies have found the exposed surface of Cu9S5 to be d(0015) and d(002) for CuS. Tetrahedral (Td) CuII, distorted octahedral (Oh) CuII, and trigonal planar (Tp) CuI sites form the d(0015) surface of Cu9S5, while the (002) surface of CuS consists of only Td CuII. The distribution of CuI and CuII sites in the lattice, predicted by PXRD, can further be validated through core-level Cu 2p X-ray photoelectron spectroscopy (XPS). The difference in the electrochemical response of Cu9S5 and CuS arises predominantly from the different copper sites present in the exposed surfaces and their redox states. In situ Raman spectra recorded during cyclic voltammetric study indicates that Cu9S5 is more electrochemically labile compared to CuS and transforms rapidly to CuO/Cu2O. Contact-angle and BET analyses imply that a high-surface-energy and macroporous Cu9S5 surface favors the electrolyte diffusion, which leads to a pronounced redox response. Post-chronoamperometric (CA) characterizations identify the potential-dependent structural transformation of Cu9S5 and CuS to CuO/Cu2O/Cu(OH)2 electroactive species. The performance of the in situ formed copper-oxides towards electrocatalytic water-splitting is superior compared to the pristine copper sulfides. In this study, the redox chemistry of the Cu9S5/CuS has been correlated to the atomic arrangements and coordination geometry of the surface exposed sites. The structure-activity correlation provides in-depth knowledge of how to interpret the electrochemistry of metal sulfides and their in situ potential-driven surface/bulk transformation pathway to evolve the active phase.

Transparent and conducting p-type (CuS)x:(ZnS)1-x thin films produced by thermal evaporation: An efficient broadband Si heterojunction photodiode

This study demonstrates the viability of the thermal evaporation method to produce transparent and highly conductive p-type (CuS)x:(ZnS)1-x thin films by achieving the highest conductivity value (1.4 × 103 S/cm) reported in this field to date. This places it in direct comparison with n-type transparent conductors. Analysis through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) unveils nanocomposite structures comprising sphalerite ZnS, chalcocite Cu2S, and covellite CuS nanocrystals in the thin films. The study reveals that transmittance values at a wavelength of 550 nm vary from 84 % to 65 % based on the increasing CuS ratio, establishing thermal-evaporated (CuS)x:(ZnS)1-x thin films as promising candidates for p-type transparent electrodes.Moreover, p+-(CuS)0.49:(ZnS)0.54/n-Si heterojunction photodiodes were also produced.The heterojunction diode exhibited excellent photo-response characteristics in a wide range of wavelengths between 325 and 1170 nm at zero-bias.The responsivity value of the photodiode was as high as 1.44 A/W at the peak wavelength of 912 nm (9.45 mW/cm2) with a high Ion/Ioffratio of 1.45 × 104. Besides, it was shown to have excellent detectivity,response time, and external quantum efficiency (EQE) values corresponding to 2.62 × 1012Jones,8.45 µs, and 244 %, respectively. Most of these values are superior to those even in commercial-grade photodiodes.

Pre-phase transition of a Cu2-xS template enables polymorph selective synthesis of MS (M = Zn, Cd, Mn) nanocrystals via cation exchange reactions.

Utilization of copper-deficient Cu2-xS nanocrystals (NCs) with diverse crystal phases and stoichiometries as cation exchange (CE) templates is a potential route to overcome the current limitations in the polymorph selective synthesis of desired nanomaterials. Among the Cu2-xS NCs, covellite CuS is emerging as an attractive CE template to produce complicated and metastable metal sulfide NCs. The presence of a reducing agent is essential to induce a phase transition of CuS into other Cu2-xS phases prior to the CE reactions. Nevertheless, the effect of the reducing agent on the phase transition of CuS, especially into the hexagonal close packing (hcp) phase and the cubic close packing (ccp) phase, has been scarcely exploited, but it is highly important for the polymorphic production of metal sulfides with the wurtzite phase and zinc blende phase. Herein, we report a reducing agent dependent pre-phase transition of CuS nanodisks (NDs) into hcp and ccp Cu2-xS NCs. 1-Dodecanethiol molecules and oleylamine molecules selectively reduced CuS NDs into hcp djurleite Cu1.94S NDs and ccp digenite Cu1.8S NCs. Afterward, the hcp Cu1.94S NDs and ccp Cu1.8S NCs were exchanged by Zn2+/Cd2+/Mn2+, and the wurtzite phase and the zinc blende phase of ZnS, CdS, and MnS NCs were produced. Without the pre-phase transition, direct CE reactions of CuS NDs are incapable of synthesizing the above wurtzite and zinc blende metal sulfide NCs. Therefore, our findings suggest the importance of the pre-phase transition of the CE template in polymorphic syntheses, holding great promise in the fabrication of other polymorphic nanomaterials with novel physical and chemical properties.

Insights into the SILAR Processing of CuxZn1-xS Thin Films via a Chemical, Structural, and Optoelectronic Assessment.

Careful analysis of the chemical state of CuxZn1-xS thin films remains an underdeveloped topic although it is key to a better understanding of the phase transformations and the linking between structural and optoelectronic properties needed for tuning the performance of CuxZn1-xS-based next-generation energy devices. Here, we propose a chemical formulation and formation mechanism, providing insights into the successive ionic layer adsorption and reaction (SILAR) processing of CuxZn1-xS, in which the copper concentration directly affects the behavior of the optoelectronic properties. Via chemical, optoelectronic, and structural characterization, including quantitative X-ray photoelectron spectroscopy, we determine that the CuxZn1-xS thin films at low copper concentration are composed of ZnS, metastable CuxZn1-xS, and CuS, where the evidence suggests that a depth compositional gradient exists, which contrasts with homogeneous films reported in the literature. The oxidation states for copper and sulfide species indicate that the films grow following a formation mechanism governed by ionic exchange and diffusion processes. At high copper concentrations, the CuxZn1-xS thin films are covellite CuS that grew on a ZnS seed layer. Hence, this work reiterates that future research related to fine-tuning the application of this material requires a careful analysis of the depth-profile compositional and structural characteristics that can enable high conductivity and transparency.

Integrated hydrothermal-green synthesis approach for covellite CuS nanoparticles with enhanced energy bandgap for BLEDs

Integrated hydrothermal-green synthesis approach for covellite CuS nanoparticles with enhanced energy bandgap for BLEDs

Dispersion stability analysis of copper sulphide nanoparticles in different medium

Nanoparticles (NPs) of covellite CuS have been synthesised using a modified polyol method at 160ºC - 165ºC without adding any extra surfactant. These NPs were charecterized by X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Analysis of X-ray (EDAX), Zeta potential and Dynamic Light Scattering (DLS) techniques. XRD data and three Raman modes confirm P63/mmc space group and hexagonal crystal structure of CuS NPs. EDAX data of Cu:S was slight differed from nominal 1:1 ratio due to extra S taken in synthesis. FESEM images show sheet-like NPs. The zeta potential (ξ) data analysis shows that the stability of the NPs is dependent on the dispersion medium, with high stability observed above pH 8.93 in an acidic medium. At pH 10.95, a highest ξ value of -37.64 mV is recorded in de-ionized water (DIW), while the nanoparticles are found to be unstable in ethanol and propanol as dispersion mediums. According to the hydrodynamic diameter (HD) data, the particles tend to agglomerate more quickly in ethanol and propanol compared to DIW. These findings are expected to be useful in various applications such as pigments in paints, batteries, pharmaceuticals, ceramics, and waste water treatment.

Localised surface plasmon resonance inducing cooperative Jahn–Teller effect for crystal phase-change in a nanocrystal

The Jahn–Teller effect, a phase transition phenomenon involving the spontaneous breakdown of symmetry in molecules and crystals, causes important physical and chemical changes that affect various fields of science. In this study, we discovered that localised surface plasmon resonance (LSPR) induced the cooperative Jahn–Teller effect in covellite CuS nanocrystals (NCs), causing metastable displacive ion movements. Electron diffraction measurements under photo illumination, ultrafast time-resolved electron diffraction analyses, and theoretical calculations of semiconductive plasmonic CuS NCs showed that metastable displacive ion movements due to the LSPR-induced cooperative Jahn–Teller effect delayed the relaxation of LSPR in the microsecond region. Furthermore, the displacive ion movements caused photo-switching of the conductivity in CuS NC films at room temperature (22 °C), such as in transparent variable resistance infrared sensors. This study pushes the limits of plasmonics from tentative control of collective oscillation to metastable crystal structure manipulation.

Surface Reconstruction of Covellite CuS Nanocrystals for Enhanced OER Catalytic Performance in Alkaline Solution.

Oxygen evolution reaction (OER) is one of the important half-reactions in energy conversion equipment such as water-spitting devices, rechargeable metal-air batteries, and so on. It is beneficial to develop efficient and low-cost catalysts that understand the reaction mechanism of OER and analyze the reconstruction phenomenon of transition metal sulfide. Interestingly, copper sulfide and cuprous sulfide with the same components possess different reconstruction behaviors due to their different metal ion valence states and different atomic arrangement modes. Because of a unique atomic arrangement sequence and certain cationic defects, the reconstruction phenomenon of CuS nanomaterials are that S2- is firstly oxidized to SO4 2- and then Cux + is converted into CuO via Cu(OH)2 . In addition, the specific "modified hourglass structure" of CuS with excellent conductivity is easier to produce intermediates. Compared with Cu2 S, CuS exhibits excellent OER activity with a lower overpotential of 192mV at 10mA cm-2 and remarkable electrochemical stability in 1.0m KOH for 120h. Herein, this study elucidates the reconstruction modes of CuS and Cu2 S in the OER process and reveals that CuS has a stronger CuS bond and a faster electronic transmission efficiency due to "modified hourglass structure," resulting in faster reconstruction of CuS than Cu2 S.

Composition controllable alga-mediated green synthesis of covellite CuS nanostructure: An efficient photocatalyst for degradation of toxic dye

A facile, convenient and green method has been devised for the synthesis of a covellite phase copper sulfide nanoparticles (CuSNPs) using aqueous extract of a green alga, Chlorella ellipsoidea. The algal phytochemicals are conjectured to have served as both reducing and capping agent. The absorption features in the NIR region of the UV–visible-NIR spectrum confirmed the formation of covellite copper sulfide nanostructures. The FTIR spectrum of the as-synthesized CuSNPs indicated the involvement of functional groups of biomolecule as surface-ligands on the outer surface of the nanoparticle. The XRD reflections were indexed to hexagonal phase covellite CuS structure. The TEM study revealed a predominantly spherical morphology of particle size in the range of 9–23 nm with some agglomeration. The dark field microscope images also confirm the formation of CuS nanoparticles. EDX analysis of the synthesized nanoparticles confirms the presence of only ‘Cu’ and ‘S’ indicating formation of pure CuS nanoparticles. The as-synthesized nanoparticles exhibited excellent photocatalytic property for the degradation of a water soluble toxic methylene blue dye under scattered sunlight. The dye degradation (rate = 0.03692 min−1) was ascertained to be pseudo-first order with regression coefficient, R2 being 0.96884. The photocatalyst is readily recoverable and showed excellent stability even after four cycles.

Manipulating Cation Exchange Reactions in Cu2-xS Nanoparticles via Crystal Structure Transformation.

Copper-deficient Cu2-xS nanoparticles (NPs) are extensively exploited as a superior cation exchange (CE) template to yield sophisticated nanostructures. Recently, it has been discovered that their CE reactions can be facilely manipulated by copper vacancy density, morphology, and NP size. However, the structural similarity of usually utilized Cu2-xS somewhat limits the manipulation of the CE reactions through the factor of crystal structure because it can strongly influence the process of the reaction. Herein, we report a methodology of crystal structure transformation to manipulate the CE reactions. Particularly, roxbyite Cu1.8S nanodisks (NDs) were converted into solid wurtzite CdS NDs and Janus-type Cu1.94S/CdS NDs by a "full"/partial CE reaction with Cd2+. Afterward, the roxbyite Cu1.8S were pseudomorphically transformed into covellite CuS NDs. Unlike Cu1.8S, the CuS was scarcely exchanged because of the unique disulfide (S-S) bonds and converted into hollow wurtzite CdS under a more reactive condition. The S-S bonds were gradually split and CuS@CdS core@shell-type NDs were generated. Therefore, our findings in the present study provide not only a versatile technique to manipulate CE reactions in Cu2-xS NPs but also a better comprehension of their reaction dynamics and pathways.

Electrochemically Derived Crystalline CuO from Covellite CuS Nanoplates: A Multifunctional Anode Material.

In the present era, electrochemical water splitting has been showcased as a reliable solution for alternative and sustainable energy development. The development of a cheap, albeit active, catalyst to split water at a substantial overpotential with long durability is a perdurable challenge. Moreover, understanding the nature of surface-active species under electrochemical conditions remains fundamentally important. A facile hydrothermal approach is herein adapted to prepare covellite (hexagonal) phase CuS nanoplates. In the covellite CuS lattice, copper is present in a mixed-valent state, supported by two different binding energy values (932.10 eV for CuI and 933.65 eV for CuII) found in X-ray photoelectron spectroscopy analysis, and adopted two different geometries, that is, trigonal planar preferably for CuI and tetrahedral preferably for CuII. The as-synthesized covellite CuS behaves as an efficient electro(pre)catalyst for alkaline water oxidation while deposited on a glassy carbon and nickel foam (NF) electrodes. Under cyclic voltammetry cycles, covellite CuS electrochemically and irreversibly oxidized to CuO, indicated by a redox feature at 1.2 V (vs the reversible hydrogen electrode) and an ex situ Raman study. Electrochemically activated covellite CuS to the CuO phase (termed as CuSEA) behaves as a pure copper-based catalyst showing an overpotential (η) of only 349 (±5) mV at a current density of 20 mA cm-2, and the TOF value obtained at η349 (at 349 mV) is 1.1 × 10-3 s-1. A low Rct of 5.90 Ω and a moderate Tafel slope of 82 mV dec-1 confirm the fair activity of the CuSEA catalyst compared to the CuS precatalyst, reference CuO, and other reported copper catalysts. Notably, the CuSEA/NF anode can deliver a constant current of ca. 15 mA cm-2 over a period of 10 h and even a high current density of 100 mA cm-2 for 1 h. Post-oxygen evolution reaction (OER)-chronoamperometric characterization of the anode via several spectroscopic and microscopic tools firmly establishes the formation of crystalline CuO as the active material along with some amorphous Cu(OH)2 via bulk reconstruction of the covellite CuS under electrochemical conditions. Given the promising OER activity, the CuSEA/NF anode can be fabricated as a water electrolyzer, Pt(-)//(+)CuSEA/NF, that delivers a j of 10 mA cm-2 at a cell potential of 1.58 V. The same electrolyzer can further be used for electrochemical transformation of organic feedstocks like ethanol, furfural, and 5-hydroxymethylfurfural to their respective acids. The present study showcases that a highly active CuO/Cu(OH)2 heterostructure can be constructed in situ on NF from the covellite CuS nanoplate, which is not only a superior pure copper-based electrocatalyst active for OER and overall water splitting but also for the electro-oxidation of industrial feedstocks.

An investigation on structural, optical and enhanced third order nonlinear optical properties of facilely synthesized Ce:CuS nanosheets

Current work reported facile chemical synthesis of hexagonal covellite CuS nanostructures with 0.0, 1.0, 3.0 and 5.0 wt% cerium doping concentrations. Scherrer’s equation used to determine the crystallites size and preferred orientation of growth plane is found along (110). Raman spectra of CuS nanostructures showed the characteristics sharp peak at the ∼ 472.21 cm−1. SEM images revealed the shape of nanostructures as nanosheets (NSs) for Ce:CuS. The band gap values of Ce:CuS NSs was computed from diffuse reflectance spectra (DRS) using Kubelka-Munk (K-M) theory which was found in range of 1.56–1.85 eV. Red and UV emission band of nanostructures can be seen in Photoluminescence spectra clearly. Third order nonlinear optics were performed by Z-scan techniques via femtosecond fiber pulsed laser. The nonlinear absorption coefficients (β) and nonlinear refractive index (n2) were found in range of 1.14 × 10-8–2.04 × 10-8 cm/W and 1.04 × 10-12–1.38 × 10-12 cm2/W, respectively. The value of third order nonlinear optical susceptibility (χ(3)) was noticed ∼ 3.36 × 10-8–5.48 × 10-8 esu. A significant improvement was observed in χ(3) with Ce incorporation in CuS lattice system. Therefore, Ce doping makes CuS potential nonlinear optical material for modern photonics device applications.

Pristine and cobalt doped copper sulfide microsphere particles for seawater splitting

In this work, copper sulfide particles are synthesized with different Co doping concentrations such as 0, 1 and 5% at 80 °C by optimizing synthesis times from 1 to 3 h. Copper sulfide particles possess two structural phases of covellite CuS and digenite Cu9S5. The increase in synthesis time from 1 to 3 h increases the Cu9S5 phase growth and changes the morphology from flower to microsphere. The CuS synthesized with 0, 1 and 5% Co dopant concentrations demonstrate flower consisting of agglomerated nanosheets, microsphere and flower like microsphere. The elemental investigation substantiates Co ions presence in CuS microspheres. The A1g (LO) mode intensity is decreased with increase in Co dopant concentration confirming Co incorporation into CuS microsphere. The CuS synthesized with 0, 1, 5% Co dopants exhibit 322 mV, 305 mV and 289 mV to attain 100 mA/cm2 in 1 M KOH seawater. The CuS synthesized with 5% Co dopant demonstrates higher double layer capacitance (Cdl) of 173.9 mFcm−2 and lower charge transfer resistance (Rct) of 6.07 Ω with 78.84% retention after 10 h continuous stability than that of the other pristine (118.3 mFcm−2, 13.72 Ω) and 1% Co doped CuS microsphere (165.7 mFcm−2, 8.55 Ω) indicating more surface active site and rapid charge carrier transport, respectively.

Physicochemical characterization and catalytic performance of Fe doped CuS thin films deposited by the chemical spray pyrolysis technique

The thin films Fe doped copper sulphide Cu1−xFexS (CFS) (x = 0.01, 0.03, 0.05, and 0.07) were elaborated by spray pyrolysis deposition technique. The characterization by XRD and SEM of the thin films shows a Covellite CuS single phase without formation of other phases. The structure is a simple hexagonal with unit cell dimension, a = b = 3.79 A and c = 16.34 A. The Analysis of the UV–Vis spectra reveals that the energy band gap has been decreased from 2.47 to 1.98 eV with the increase of Fe concentration. The absorption coefficients of CFS films have increased from 1.155 × 105 to 1.712 × 105 cm−1. It has demonstrated that a right band gap with a right band edge alignment at a pH value for Fe-doped CFS can boost the material application as a photocatalyst for the visible light. According to this study, CFS (0.07) thin films for a pH = 3 solutions is a promising material for photocatalysis application for water splitting to hydrogen-oxygen production. Nevertheless, we demonstrate that the formation of straddling gap heterostructure for CuS and CFS for a pH solution between 7 and 8 induces the production of oxygen and hydrogen.

Mechanochemical Reduction of Synthetic Sulphidic Copper-Bearing Minerals in an Industrial Scale

In this paper the mechanochemical reduction of binary sulphides chalcocite (Cu2S) and covellite (CuS) by elemental iron wereinvestigated. The composition and properties of nano-powders prepared by high-energy milling were analyzed by X-ray diffraction,X-ray photoelectron spectroscopy and magnetic measurements. The XRD results showed that in case of chalcocite Cu2S the reactiontakes place until 360 minutes, as no elemental iron, could be identified afterwards. In case of covellite CuS, after 480 minutes of mechanochemicalreduction, a significant amount of non-reacted elemental iron could still be observed. The investigation of magneticproperties reveals significant decrease of saturation magnetization as a result of milling. XPS results showed a significant surfaceoxidation in both systems. Unlike the conventional high-temperature reduction of chalcocite and covellite, the mechanochemicalreduction is fast and ambient temperature and atmospheric pressure are sufficient for its propagation.

Radiation-induced synthesis of copper sulfide nanotubes with improved catalytic and antibacterial activities.

In the current paper, copper sulfide nanotubes have been successfully synthesized via the green, simple, and effective gamma-radiolysis method without adding any capping or reducing agents. The structural and morphological characteristics of the as-prepared CuS nanotubes were investigated by X-ray diffraction (XRD), N2 adsorption-desorption measurements at 77K, transmission electron microscopy (TEM), and ultraviolet-visible (UV-vis) spectroscopy, which all demonstrated the formation of pure CuS covellite phase with tubular morphology. The synthesized CuS nanotubes possessed not only high activity towards the reduction of both cationic (methylene blue) and anionic (Congo red) dyes in the presence of NaBH4 but also exhibited excellent reusability. In addition, the pseudo-first-order kinetic model represented the reduction of MB very well, and the value of the normalized rate constant (2.4 × 10-2s-1mg-1) was higher than those of other solid catalysts reported in the literature. Ultimately, CuS nanotubes were found to have a broad-spectrum microbicidal action against the common microbiota, such as Gram-positive (exemplified by Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (exemplified by Pseudomonas aeruginosa and Escherichia coli), yeast (exemplified by Candida albicans), and plant pathogenic fungi (exemplified by Aspergillus niger).