Synthesized Copper Sulfide Research Articles

Temperature-dependent electrochemical performance of CuS as electrode material for supercapacitor application

In this work, we synthesize copper sulfide as electrode materials using hydrothermal technique at different temperatures. The electrochemical performance of copper sulfide electrode in 3-electrode systems using 2 M KOH electrolyte is thoroughly studied using electrochemical techniques such as CV, GCD and EIS. The sample synthesized at 160 °C demonstrates that it has a specific capacitance of 232.5F/g at a charge–discharge current density of 1 A/g, maintains cyclic stability of 72.57 % during 500 GCD cycles at 5 A/g, highlighting its potential for supercapacitors applications. The results demonstrate that temperature significantly alters the electrochemical properties of the CuS.

Significance of synthesized digenite phase of copper sulfide nanoparticles as a photocatalyst for degradation of bromophenol blue from contaminated water

Organic pollutants such as phenolic compounds have received global interest since they are harmful, toxic, and carcinogenic. This work aimed to synthesize copper sulfide nanoparticles in digenite phase (Cu1.8S) via sol–gel method and apply it as a photocatalyst to remove a phenolic contaminate, bromophenol blue (BPB) dye, from water. The copper sulfide nanoparticles were prepared by the sol–gel technique under different conditions, such as reaction temperature, reactant concentration, and aging time, in the presence of a stabilizing agent (cetyltrimethylammonium bromide, CTAB). The synthesized nanoparticles were then described using different characterization techniques. Then these nanoparticles were applied as a photocatalyst for the degradation of bromophenol blue (BPB) under different conditions, including photo-irradiation time, catalyst dosage, dye concentration and power lamp. The aimed copper sulfide digenite nanoparticles (Cu1.8S) were obtained at a 3 h aging time, exhibiting a cubic crystal structure and a size of 8 nm in a 3-dimensional closed-packed structure model with an energy band gap of 1.82 eV. This material has the ability to absorb visible light and thus can be a superior candidate for photocatalysis, demonstrating strong photocatalytic activity towards the degradation of the phenolic dye (i.e., BPB). Excellent results were achieved at a contact time of 3 h, 7 ppm of BPB, 50 mg catalyst dose, and 32 W power lamp. As a consequence, about 96.7% of the contaminants were removed. The photocatalytic degradation was found to obey the Langmuir postulate and exhibit pseudo first order kinetics.

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.

Sodium Alginate-CuS Nanostructures Synthesized at the Gel-Liquid Interface: An Efficient Photocatalyst for Redox Reaction and Water Remediation.

The use of visible light to propel chemical reactions is an exciting area of study that is crucial in the current socioeconomic environment. However, various photocatalysts have been developed to harness visible light, which consume high energy during synthesis. Thus, synthesizing photocatalysts at gel-liquid interfaces in ambient conditions is of scientific importance. Herein, we report an environmentally benign sodium alginate gel being used as a biopolymer template to synthesize copper sulfide (CuS) nanostructures at the gel-liquid interface. The driving force for the synthesis of CuS nanostructures is varied by changing the pH of the reaction medium (i.e., pH 7.4, 10, and 13) to tailor the morphology of CuS nanostructures. The CuS nanoflakes obtained at pH 7.4 transform into nanocubes when the pH is raised to 10, and the nanostructures deform at the pH of 13. Fourier transform infrared spectroscopy (FTIR) confirms all the characteristic stretching of sodium alginate, whereas the CuS nanostructures are crystallized in a hexagonal crystal system, as revealed by the powder X-ray diffraction analysis. The high-resolution X-ray photoelectron spectroscopy (XPS) spectra show the +2 and -2 oxidation states of copper (Cu) and sulfur (S) ions, respectively. The CuS nanoflakes physisorbed a higher concentration of greenhouse CO2 gas. Owing to a lower band gap of CuS nanoflakes synthesized at a pH of 7.4, compared to other CuS nanostructures prepared at pH 10 and 13, CuS photocatalytically degrades 95% of crystal violet and 98% of methylene blue aqueous dye solutions in 60 and 90 min, respectively, under blue light illumination. Additionally, sodium alginate-copper sulfide (SA-CuS) nanostructures synthesized at a pH of 7.4 demonstrate excellent performance in photoredox reactions to convert ferricyanide to ferrocyanide. The current research opens the door to developing new photocatalytic pathways for a wide range of photochemical reactions involving nanoparticle-impregnated alginate composites prepared on gel interfaces.

Effect of different precursors on the electrochemical behavior of CuS nanostructures as electrode material for supercapacitor applications

In the present work, we synthesized copper sulfide (CuS) nanostructure using the co-precipitation technique by employing two different copper precursors such as copper nitrate, copper chloride with water as a solvent in order to investigate the effect of different precursors on the electrochemical behavior of CuS nanostructures as electrode material for supercapacitor application. X-ray diffraction analysis confirmed the pure phase (hexagonal-P63/mmc) formation of CuS nanostructures. The morphological and elemental compositional studies are done by scanning electron microscopy and energy-dispersive X-ray spectroscopy respectively. Electrochemical characterizations like cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) were utilized to analyze the super capacitive properties of the fabricated electrode material in a three-electrode system using 2 M KOH solution as an aqueous electrolyte. The highest value of specific capacitance is found to be 346.66F/g at 2 A/g for the sample synthesized via copper nitrate precursor. Furthermore, it also displayed good cycling stability with more than 80 % retention of capacitance over 500 GCD cycles. Hence, the analysis of the result revealed that precursors play a major role in modifying the electrochemical properties.

Chemically synthesized copper sulfide nanoflakes on reduced graphene oxide for asymmetric supercapacitors

The present work describes the deposition of coppersulfide (Cu2S) nanoflakes onto reduced graphene oxide (rGO) on three dimensional (3D) nickel foam byinexpensive chemical methods. The nanohybrid structure exhibitedexcellent surface area (41.67m2g−1) with a porous structure (pore size 22.8nm) and good electrical conductivity with a maximum specific capacitance of 1264Fg−1 at a scan rate of 5mVs−1. The Cu2S@rGOcomposite exhibits a significantlyhigher specific capacitance. The nanohybrid structure showed outstandingcycling stability of 94 % after 10000cycles. The asymmetric supercapacitor (ASC) device, Cu2S@rGO//rGO exhibited a maximumspecific capacitance of 135Fg−1 withhighenergy and power densities of 50Whkg−1, and 7000Wkg−1, respectively.

Morphology-dependent thermoelectric properties of mixed phases of copper sulfide (Cu2−xS) nanostructures synthesized by hydrothermal method

In this research work we have synthesized copper sulfide (Cu2−xS) nanostructures by the hydrothermal method. The post-sulfurization was performed by using tube furnace to reduce sulfur deficiency and to minimize impurities present in the crystal-lattice. The samples were synthesized by various pH values of precursor solution. The samples were characterized by XRD, RAMAN spectroscopy, SEM, Hall measurements and Seebeck effect. XRD analysis revealed the formation of hexagonal covellite (CuS) and chalcocite (Cu2S) phases of copper sulfide. Despite these phases XRD data also showed the dominating hexagonal digenite (Cu1.8S) phase of copper sulfide. We observed a decreasing trend in average crystalline size with the increasing pH values of the samples from the XRD data. We have found maximum average crystalline size of 39.1679 nm at pH value of 4. The formation of LO mode of hexagonal covellite phase of copper sulfide was observed from RAMAN analysis. The SEM images revealed the formation of flower-like nanostructures at the lowest pH value. It strengthened our argument that the crystallinity of nanostructures is inversely proportional to the pH value. We have achieved maximum values of Seebeck coefficient and conductivity at room temperature as 73.920 µV/K and 0.909 S/cm, respectively. The Seebeck coefficient and conductivity graphs showed an increasing trend due to the energy filtering effect in mesoporous structure. The maximum value of power factor was 4.91 × 10–7 Wm−1 K−2.

Antimicrobial Activity of the Synthesized of Copper Chalcogenide Nanoparticles

Antimicrobial activity of copper chalcogenides nanoparticles was investigated by synthesizing copper selenide, copper sulfide, and copper oxide via the hot-injection method. Since reaction time has a profound effect on the nanocrystals size and shapes, the effect of reaction time was also investigated during the synthesis of the copper chalcogenides to obtain nanocrystals with desired properties. The reaction time showed no effect on the phase composition of the synthesized copper sulfide, copper oxide, and copper selenide nanoparticles. However, the size variation of nanoparticles with different reaction time was observed. Reaction time of 30 minutes gave the best optical (the shape of the absorption band edge and emission maxima values) and structural (size distribution of particles) properties for CuSe and CuS compared to other reaction times (15, 45, and 60 min). Their band edges were located at 506 (2.45 eV) and 538 nm (2.30 eV), respectively. For this reaction time, copper selenide produced nanoparticles with a size range of 1–27 nm and copper sulfide nanoparticles ranged 1–18 nm. The morphologies of both chalcogenides at 30 min reaction time were spherical. Reaction time of 15 minutes gave the best optical and structural properties for copper oxide nanoparticles with a band edge of 454 nm (2.73 eV) and particle size ranging 0.8–3.2 nm, but nonetheless, 30 min was used as the optimum reaction time for all three chalcogenides. The optimum parameter (220°C, 30 min, and 1 : 1 ratio) was used to synthesize the three copper chalcogenides which were then tested against Gram-negative (E. coli and P. aeruginosa), Gram-positive (S. aureus and E. faecalis), and fungi (C. albicans) employing both agar disk diffusion and minimum inhibitory concentration (MICs) methods. Copper oxide nanoparticles showed more sensitivity towards four bacterial microorganisms than the other two chalcogenides followed by copper sulfide nanoparticles with copper selenide nanoparticles being the least sensitive. The sensitivity of copper oxide nanoparticles is attributed to the smaller size of oxygen atom which strongly affects its reactivity and stability and hence very stable and highly reactive compared to sulfur and selenium.

Electrochemical hydrogen-storage performance of copper sulfide micro-hexagons

Electrochemical hydrogen-storage is one of the prominent energy storage systems. In this work, the hydrothermally synthesized copper sulfide (Cu2S) revealed a unique morphology of micro-hexagons as envisioned through scanning electron microscopy measurements. Electrochemical hydrogen storage (EHS) performance was evaluated using various electrochemical techniques, such as cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy measurements. The hydrogen discharge capacity of ~59.32 mAh g−1 was obtained at an applied current density of 1 A g−1. Further, the analysis of the charge-storage mechanism indicates foremost contributions from the redox processes. The prominent hydrogen storage performance is complimented with reasonable cyclic retention for 2500 cycles.

Extensive evaluation of changes in structural, chemical and thermal properties of copper sulfide nanoparticles at different calcination temperature

Present study is related to synthesize copper sulfide (CuS) nanoparticles by co-precipitation method varying calcinations temperature regimes (250,500 and 750 °C) respectively. These nanoparticles (NPs) were characterized by using various characterization techniques such as XRD, SEM, EDX, FTIR and TGA. Deviation in crystallite size, crystal structure (hexagonal, rhombohedral and monoclinic), texture coefficient and lattice parameters were identified by using XRD analysis. SEM micrograph represented that the grain size increase by increasing temperature and EDX graph shows the elemental composition of nanomaterials. Moreover, the FTIR analysis depicted the different rotational and vibrational mode attached to the surface of CuS-NPs and thermogravimetric analysis (TGA) used to identify phase shifting with varying temperature. Finally, structural analysis revealed that with increase in temperature as-synthesized. CuS transform into non-stoichiometric Cu9S5 at 250 °C to CuSO4 at 500 °C and then change into CuO (750 °C).

Vancomycin modified copper sulfide nanoparticles for photokilling of vancomycin-resistant enterococci bacteria

Due to the overuse of antibiotics, vancomycin resistant enterococci (VRE) has caused serious infections and become more and more difficult to deal with. Herein, we reported a facile one-pot strategy to synthesize copper sulfide nanoparticles using vancomycin (Van) as reductant and capping agent (CuS@Van). The as-prepared CuS@Van nanocomposites presented excellent uniformity in particle size and strong near infrared (NIR) absorbance. Fourier Transform infrared spectroscopy (FTIR) and Energy dispersive spectrometry (EDS) analysis confirmed the successful modification of Van molecules on the surface of CuS@Van nanoparticles. Bacterial TEM images verified the specific binding affinity between CuS@Van and VRE pathogen. CuS@Van also exhibited effective photokilling capability based on a combination of photothermal therapy (PTT) and photodynamic therapy (PDT). Fluorescent bacterial viability staining and bacterial growth curves monitoring were performed to explore the photokilling ablation of CuS@Van against VRE pathogens. The in vitro results indicated that CuS@Van nanocomposites had no antibacterial activity in the dark but displayed satisfying bactericidal effect against VRE pathogens upon the NIR irradiation. Mouse infection assays were also implemented to evaluate in vivo antibacterial photokilling effectiveness. CuS@Van with NIR irradiation showed the highest antibacterial capability and fastest infection regression compared with the control groups. Considering the low cost, easy preparation, good biocompatibility and excellent photokilling capability, CuS@Van nanocomposites will shed bright light on the photokilling ablation of vancomycin-resistant pathogenic bacteria.

Copper sulfide nanoparticles suppress Gibberella fujikuroi infection in rice (Oryza sativa L.) by multiple mechanisms: contact-mortality, nutritional modulation and phytohormone regulation

This study demonstrates that synthesized copper sulfide nanoparticles with a rapid Cu dissolution rate can suppress Gibberella fujikuroi infection in rice (Oryza sativa L.).

Antifungal potential of zinc ion coated copper sulfide nanoforms against Fusarium verticillioides

The work pertains to the enhanced antifungal activity of Zn2+ capped CuS nano forms against Fusarium verticillioides. Zinc ions (in different molar ratios) were used as capping as well as stabilizing agent for sonochemically synthesized copper sulfide nanoforms. The SEM, TEM and UV–Visible spectrometry indicated non-significant difference in morphology, particle size and optical properties of different Zn+2CuSI–III. The particle size distribution and zeta potential analysis indicated the proportional relation in hydrodynamic diameter with zeta potential which increased with increase in concentration of Zn+2 ion capped on CuS nanoparticles. Comparative in vitro antifungal evaluation studies of naked CuS and Zn+2CuSIIII against F. verticillioides indicated increased efficacy of Zn+2CuSIII (with Zn+2CuS in 6:1 molar ratio) nano formulations than non Zn+2 coated formulations against the test fungus. Seed priming with the synthesized Zn2+ CuSIII resulted in improved seed germination and reduced seed rot and seedling mortality at a lower concentration than non zinc ion coated copper sulfide nano-aqua-formulations.

Quaternized chitosan-stabilized copper sulfide nanoparticles for cancer therapy

In this study, we report a smart and green strategy to synthesize copper sulfide nanoparticles (CuS-NPs) for clinically translatable cancer treatment. For the first time, the preparation of CuS-NPs was developed by taking advantage of the copper-amine complex as the copper source and sodium sulfide as the sulfide source, in which the quaternized chitosan (QCS) was used as a biotemplate and stabilizing agent. The obtained QCS/CuS-NPs composites (CuS@QCS-NPs) were spherical and stable with an average diameter of 5.6 nm, and showed strong NIR absorbance for photothermal conversion. Moreover, in vitro and in vivo cancer theranostic capability of CuS@QCS-NPs without any biomodification was evaluated. The result reveals that after intratumoral (i.t.) injection of CuS@QCS-NPs with NIR laser irradiation (808 nm, 1.5 W/cm2, 5 min), the 4T1 mammary tumor growth could be effectively suppressed comparing with the other control groups, and there was no obvious lethal toxicity to liver function, kidney function, and vital organs. Such QCS-stabilized CuS-NPs may provide an alternative for clinical application of CuS-based photothermal therapy.

Role of precursors in controlling the size, shape and morphology in the synthesis of copper sulfide nanoparticles and their application for fluorescence detection

Synthesis of well controlled pure phase of CuS with defined shapes and sizes remains a challenge for effective applications. We studied the role of copper and sulfur source precursors in controlling the size, shape and morphology of CuS nanostructures using synthesized refluxing method. CuS nanoparticles are synthesized by varying Cu(CH3COO)2·H2O, Cu(NO3)2·3H2O, CuSO4·5H2O as copper precursors and CH4N2S, Na2S2O3·5H2O, Na2S as sulfur precursors. As synthesized copper sulfide nanoparticles were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray (EDX), Ultra Violet - visible spectrophotometer (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), and micro Raman spectroscopy. All precursors result into nano-size single phase covellite copper sulfide, except sodium sulfide as a sulfur source which resulted into mixed phases. Morphology of nano-systems varies (hexagonal plate like, tube like, cluster of nanoparticles, plate like and ball like nanostructures) with varying precursors. TEM images show particle size variation (particle size 20–25 nm). Elemental analysis using EDX confirm that stoichiometric ratio of Cu/S is approximately 1:1 which is in good agreement with the starting molar ratio. FT-IR and Raman spectra confirm the absence of Cu2S and the band width of S-S stretch mode is correlated with particle size. Optical energy band gap varies in the range 1.80–2.31 eV and is also correlated with crystalline size. The release rate of S2− ions in sulfur source and polarization of counter anion in copper source are found to be the deciding factors in controlling the size, shape and morphology.

“Green” synthesis of Cu2S nanoparticles from (Z)-1-methyl-2-(pyrrolidin-2-ylidene)thiourea ligand for the preparation of Cu2S-chitosan nanocomposites for the removal of Cr(VI) ion from wastewater

Synthesis of copper sulfide nanoparticles through homogeneous precipitation method and the preparation of Cu2S–chitosan nanocomposites for the removal of Cr(VI) ions from wastewater samples has been achieved. The absorption studies revealed a blue shift in the wavelengths of the band edges when the starch or PVA was introduced into the nanoparticles. The structural studies of the particles were carried out using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns presented the cubic Cu1.8S phase for all the synthesized copper sulfide nanoparticles. TEM images showed spherical shaped particles which became agglomerated when the stabilizers were introduced into the nanomaterial. The adsorption studies proved that the parameters such as pH, dosage and contact time plays an important part during the water treatment.

Plasmonic electron deficient Cu2−xS semiconductor nanoparticles from cyclohexylamine-N-dithiocarbamate ligand

Cyclohexylamine-N-dithiocarbamate ligand was prepared and used to synthesize Cu complex [Cu(S2CNC6H12)2]. The effect of capping molecule was studied through the thermolysis of the precursor in hexadecylamine (HDA) and tri-octylphosphine-n-oxide (TOPO) to give HDA and TOPO-capped CuS nanoparticles by varying their concentrations. The absorption spectra showed localized surface plasmon resonances (LSPR) and quantum confinement effect for all samples. TEM micrographs displayed well-dispersed isotropic particles for the sample prepared at higher concentration of HDA and anisotropic particles for the sample prepared at lower concentration which was different with TOPO capped nanoparticles. The synthesized copper sulfide nanoparticles revealed hexagonal phase.

Chemical Precipitation Synthesis and Thermoelectric Properties of Copper Sulfide

Earth-abundant copper sulfide compounds have been intensively studied as potential thermoelectric materials due to their high dimensionless figure of merit ZT values. They have a unique phonon-liquid electron-crystal model that helps to achieve high thermoelectric performance. Many methods, such as melting and ball-milling, have been adopted to synthesize this copper sulfide compound, but they both use expensive starting materials with high purity. Here, we develop a simple chemical precipitation approach to synthesize copper sulfide materials through low-cost analytically pure compounds as the starting materials. A high ZT value of 0.93 at 800 K was obtained from the samples annealed at 1273 K. Its power factor is around 8.0 μW cm−1 K−2 that is comparable to the highest record reported by traditional methods. But, the synthesis here has been greatly simplified with reduced cost, which will be of great benefit to the potential mass production of thermoelectric devices. Furthermore, this method can be applied to the synthesis of other sulfur compound thermoelectric materials.

Influence of Thickness on the Photosensing Properties of Chemically Synthesized Copper Sulfide Thin Films

We report here the influence of thickness on the photosensing properties of copper sulfide (CuS) thin films. The CuS films were deposited onto glass substrate by using a simple and cost effective chemical bath deposition method. The changes in film thickness as a function of time were monitored. The films were characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FE-SEM), optical measurement techniques and electrical measurement. X-ray diffraction results indicate that all the CuS thin films have an orthorhombic (covellite) structure with preferential orientation along (113) direction. The intensity of the diffraction peaks increases as thickness of the film increases. Uniform deposition having nanocrystalline granular morphology distributed over the entire glass substrate was observed through FE-SEM studies. The crystalline and surface properties of the CuS thin films improved with increase in the film thickness. Transmittance (except for 210 nm thick CuS film) together with band gap values was found to decrease with increase in thickness. I-V measurements under dark and illumination condition show that the CuS thin films give a good photoresponse.

Single-Source Molecular Precursor for Synthesis of Copper Sulfide Nanostructures

As a new precursor, [bis(thiosemicarbazide)copper(II)]chloride; ([Cu(TSC)2]Cl2), complex was used in thermal decomposition process for the synthesis of Cu2S nanocrystals. The steric hindrance of the precursor raises the need of using co-surfactant, therefore oleylamine (C18H37N) and triphenylphosphine (C18H15P) were applied as solvent and surfactant of the reaction. CuS nanocrystals were synthesized via hydrothermal decomposition of [bis(thiosemicarbazide) copper(II)] without any surfactant. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. Synthesized copper sulfide nanostructures have average size of 20–50 nm. Finally, optical properties of the products were examined and investigated by PL spectra.