CuS Nanosheets Research Articles

Flexible Binder‐Free CuS/Polydopamine‐Coated Carbon Cloth for High Voltage Supercapacitors

AbstractInterfacial engineering is important to achieve high electrochemical performance in energy storage devices. It becomes particularly important for flexible devices, where stresses at the interface between the active material and current collector can be significant upon flexing. Here, we describe simple yet powerful method to tune surface properties, such as wettability and adhesion of carbon cloth (CC) as current collectors to active materials via using dopamine chemistry. We show how a polydopamine‐coated CC (p‐CC) exhibits strong adhesion with CuS nanosheets, enabling negligible capacitance fading after over 100 folding cycles. The CuS/p‐CC system exhibits attractive electrochemical properties, including a high specific capacitance (337 F g−1 at 0.5 A g−1), good rate capability (81.9 % capacitance retention at a rate of 10 A g−1), and excellent capacitance retention (about 96.1 % after 1000 cycles). An asymmetric supercapacitor fabricated by assembly of RGO/p‐CC and CuS/p‐CC provides a stable cell voltage up to 1.5 V and energy and power densities of up to 48.3 Wh kg−1 and 6919 W kg−1 on a full electrode basis.

One‐Pot Synthesis of CuS Nanoflower‐Decorated Active Carbon Layer for High‐Performance Asymmetric Supercapacitors

AbstractCopper sulfide‐active carbon (CuS‐AC) with a three‐dimensional (3D) porous structure is fabricated based on AC‐supported CuS nanosheets by using a solvothermal method and used in a high‐performance asymmetric supercapacitor devices to enhance the specific capacitance, cycling stability, and energy density. The CuS nanosheets form an array on the AC layer, and the two kinds of materials are ideally combined, leading to increased conductivity and enlarged electroactive surface area of the electrode materials. Moreover, the 3D CuS‐AC porous structure exhibited excellent electrochemical energy storage properties with large specific capacitance (247 F g−1 at a current density of 0.5 A g−1), high energy density (24.88 Wh kg−1 at the power density of 800 W kg−1), and good long‐term cycling stability (92% capacitance retention after 5000 cycles). This superior electrochemical performance can be ascribed to the high pseudocapacitance of CuS and large surface area from AC. The experimental results indicate that the hierarchical nanostructure design of CuS grown on AC exhibits considerable potential for supercapacitor applications.

Facial Grinding Method for Synthesis of High-Purity CuS Nanosheets

High-purity CuS nanosheets have been successfully synthesized at room temperature via a quick, simple, and efficient grinding approach by using CuCl2·2H2O, thiourea, and NaOH as starting materials. The X-ray diffraction (XRD) patterns and Raman spectra indicated that as-prepared CuS was of high purity and scanning electron microscope (SEM) images showed the sheet-like nanostructure. The specific area of as-synthesized CuS nanosheets was obtained with a N2 adsorption/desorption isotherm, and the value is 23.18 m2·g–1, which is higher than that of CuS fabricated by the traditional method. The bandgap of the as-synthesize CuS was calculated to be around 1.8 eV corresponding to the UV–vis diffuse reflection spectra, showing a potential prospect in photocatalysis and solar cells. A 10-g-level production also has been achieved in our laboratory, and the yield was over 95% based on the Cu source. The grinding approach can be a promising method for the industrial-scale production of high-purity CuS nanosheets.

Synthesis and Characterization of Two Dimensional Copper Selenide (CuSe) Nanosheets

Two dimensional metal chalcogenides are promising candidate for optoelectronics owing to their interesting physical and chemical properties. In the present work, 2-D layer structured CuSe nanosheets were developed by simple hot injection method. Oleic acid has been employed as solvent as well as capping agent and CuCl, elemental sulfur have been used as precursors at the reaction temperature of 220OC. Crystallinity and phase of the products were characterized by X-ray diffraction (XRD). XRD patterns confirm the presence of hexagonal Klockmannite (CuSe) with space group of P63/mmc. Morphological analyses were carried out through SEM analysis which depicts the 2-D layered nanosheets of CuSe with two different orientations of nanosheets. Elemental composition of copper to selenium ratio was confirmed through Energy dispersive X-ray spectroscopy (EDS) which reveals the stoichiometry of CuSe nanosheets. The EDS results are in line with the XRD results. Optical properties were analysed through UV-Vis absorption spectroscopy in the wavelength range of 350 nm to 900 nm. The presence of capping agent over the CuSe nanosheets were confirmed from Fourier transform infrared spectroscopy (FT-IR).

A high-response transparent heater based on a CuS nanosheet film with superior mechanical flexibility and chemical stability.

Transparent heaters are widely used in technologies such as window defrosting/defogging, displays, gas sensing, and medical equipment. Apart from mechanical robustness and electrical and optical reliabilities, outstanding chemical stability is also critical to the application of transparent heaters. In this regard, we first present a highly flexible and large-area CuS transparent heater fabricated by a colloidal crackle pattern method with an optimized sheet resistance (Rs) as low as 21.5 Ω sq-1 at a ∼80% transmittance. The CuS transparent heater exhibits remarkable mechanical robustness during bending tests as well as high chemical stability against acid and alkali environments. In the application as a transparent heater, the CuS heater demonstrates a high thermal resistance of 197 °C W-1 cm2 with a fast switching time (<30 s), requiring low input voltages (<4.5 V) to achieve uniform temperatures of ∼110 °C across large areas. The temperature of the wearable CuS heater, which is stuck on the skin, can be real-time controlled through a Bluetooth device in a cell phone wirelessly. Based on the wireless control system, we demonstrated an application of the CuS heater in snow removal for solar panels. These CuS network TCEs with high flexibility, transparency, conductivity, and chemical stability could be widely used in wearable electronic products.

Copper sulfide nanosheets with shape-tunable plasmonic properties in the NIR region.

2D copper sulfide nanocrystals are promising building blocks of plasmonic materials in the near-infrared (NIR) spectral region. We demonstrate precise shape and size control (hexagonal/triangle) of colloidal plasmonic copper sulfide (covellite) nano-prisms simply by tuning the precursor concentration without the introduction of additional ligands. The ultra-thin 2D nanocrystals possess sizes between 13 and 100 nm and triangular or hexangular shapes. We also demonstrate CuS nanosheets (NSs) with lateral sizes up to 2 microns using a syringe pump. Based on the experimental findings and DFT simulations, we propose a qualitative and quantitative mechanism for the formation of different shapes. The analysis of the spectral features in the NIR region of the synthesized CuS nanocrystals has been performed with respect to the shape and the size of particles by the discrete dipole approximation method and the Drude-Sommerfeld theory.

Graphene‐Like Multilayered CuS Nanosheets Assembled into Flower‐Like Microspheres and Their Electrocatalytic Oxygen Evolution Properties

AbstractGraphene‐like two‐dimensional (2D) nanomaterials have many unique properties in diverse fields, but the synthesis method of graphene‐like CuS 2D nanomaterials is rarely studied. In this work, we reported that the CuS flower‐like superstructure microspheres with a solid core (CuS‐FSMs) were prepared by a facile hydrolysis method without a template or surfactant. The novel CuS‐FSM material showed a well‐define solid core of approximately 300–500 nm and a loose shell of 0.5–1 μm. More importantly, the loose shell of the CuS‐FSMs was constructed of graphene‐like CuS nanosheets (CuS‐GN). The formation mechanism indicated that the CuS‐FSMs were firstly formed on the surface of hexagonal prism‐shaped Cu3(TAA)3Cl3 precursors, and then the well‐defined solid core was produced through the Ostwald ripening of CuS‐GN. The electrocatalytic oxygen evolution reaction was employed as a probe reaction to gain insight into the properties of CuS‐FSMs, which exhibited a high limiting current density of 92.4 mA cm−2 and stability in 1 M KOH electrolyte.

Facile fabrication of g-C3N4/ZnS/CuS heterojunctions with enhanced photocatalytic performances and photoconduction

The construction of high-quality graphitic carbon nitride (g-C3N4)-based heterojunctions remains a grand challenge. Herein, the ternary heterojunctions of g-C3N4/ZnS/CuS has been fabricated via a facile three-step process: the polymerization of melamine, the loading of ZnS nanoparticles (NPs), and further deposition of hexagonal CuS nanosheets. Compared with pure g-C3N4, there is an extended visible-light absorption over 500–800 nm for g-C3N4/ZnS/CuS, which enables the possible utilization of low-energy visible light. Moreover, ZnS NPs interface layers and hexagonal CuS nano-sheets can be both utilized as electron co-catalysts to markedly improve the separation efficiency of the photo-generated electrons and holes and decrease interface transfer resistance, resulting in highly efficient photocatalytic activity for degradation of Rhodamine B (RhB) and significantly enhanced photoconductivity in an all-solid-state device. This work can be helpful for developing other effective hetero-structured photocatalysts and photoelectrical devices.

Sputtered seed-assisted growth of CuS nanosheet arrays as effective counter electrodes for quantum dot-sensitized solar cells

CuS nanosheet arrays (NSAs) obtained by combining a physical radio frequency (RF) sputtered CuS seeding process with a facile and green hydrothermal post-treatment, are employed as counter electrodes (CEs) for quantum dot-sensitized solar cells (QDSSCs). Such CuS NSAs show superior electrocatalytic ability as compared to the conventional Pt CEs and other three types of CuS nanosheet films prepared via different methods.

Vertically Oriented and Interpenetrating CuSe Nanosheet Films with Open Channels for Flexible All-Solid-State Supercapacitors.

As a p-type multifunctional semiconductor, CuSe nanostructures show great promise in optoelectronic, sensing, and photocatalytic fields. Although great progress has been achieved, controllable synthesis of CuSe nanosheets (NSs) with a desirable spacial orientation and open frameworks remains a challenge, and their use in supercapacitors (SCs) has not been explored. Herein, a highly vertically oriented and interpenetrating CuSe NS film with open channels is deposited on an Au-coated polyethylene terephthalate substrate. Such CuSe NS films exhibit high specific capacitance (209 F g–1) and can be used as a carbon black- and binder-free electrode to construct flexible, symmetric all-solid-state SCs, using polyvinyl alcohol–LiCl gel as the solid electrolyte. A device fabricated with such CuSe NS films exhibits high volumetric specific capacitance (30.17 mF cm–3), good cycling stability, excellent flexibility, and desirable mechanical stability. The excellent performance of such devices results from the vertically oriented and interpenetrating configuration of CuSe NS building blocks, which can increase the available surface and facilitate the diffusion of electrolyte ions. Moreover, as a prototype for application, three such solid devices in series can be used to light up a red light-emitting diode.

Electrodeposition of CuSe Nanosheets films and its growth mechanism

Copper selenide nanosheets films were synthesized successfully by simple electrodeposition method with controlling various experimental parameters. CV was used to study its growth process. It demonstrated that copper selenium is formed by an induced co-deposition mechanism where selenium is deposited first and then the reduction of Cu+ is induced, finally the formation of copper selenide nanostructures is finished.

Preparation and Optical Properties of CuS Nanofilms by a Facile Two-Step Process

CuS nanofilms were prepared by a facile two-step process including chemical bath deposition of Cu nanofilms first and the subsequent thermal sulfuration step. The composition and structure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The optical properties of CuS nanofilms were determined by Ultraviolet-visible (UV-Vis) technique. The results show that the nanofilms composed by Cu spherical nanoparticles were completely transformed to the nanofilms composed by CuS nanosheets when the sulfuration temperature was 350[Formula: see text]C. The light absorption edges of CuS nanofilms exhibit red shift when sulfuration occurred at lower temperature. A plausible growth mechanism related with gas phase reaction for formation of CuS nanofilms was also proposed.

Significantly Improved Sodium-Ion Storage Performance of CuS Nanosheets Anchored into Reduced Graphene Oxide with Ether-Based Electrolyte.

Currently sodium-ion batteries (SIBs) as energy storage technology have attracted lots of interest due to their safe, cost-effective, and nonpoisonous advantages. However, many challenges remain for development of SIBs with high specific capacity, high rate capability, and long cycle life. Therefore, CuS as an important earth-abundant, low-cost semiconductor was applied as anode of SIBs with ether-based electrolyte instead of conventional ester-based electrolyte. By incorporating reduced graphene oxide (RGO) into CuS nanosheets and optimizing the cutoff voltage, it is found that the sodium-ion storage performance can be greatly enhanced using ether-based electrolyte. The CuS-RGO composites deliver an initial Coulombic efficiency of 94% and a maximum specific capacity of 392.9 mAh g-1 after 50 cycles at a current density of 100 mA g-1. And a specific capacity of 345 mAh g-1 is kept after 450 cycles at a current density of 1 A g-1. Such an excellent electrochemical performance is ascribed to the conductive network construction of CuS-RGO composites, the suppression of dissolved polysulfide intermediates by using ether-based electrolyte, and the avoidance of conversion-type reaction by optimizing the cutoff voltage.

Efficient and stable electroreduction of CO2to CH4on CuS nanosheet arrays

Efficient electrocatalytic activity for CO2reduction based on CuS nanosheet arrays is first presented. The resultant electrode exhibits high catalytic activity and durability for CO2electroreduction.

Facile synthesis of CuS nanosheets probe for resonance light scattering and visual detecting l-cysteine

A highly efficient resonance light scattering (RLS) and visual probe based on mercaptosuccinic acid (MA) modified copper sulfide (CuS) nanosheets has been successfully established for sensitive and selective detection of l-cysteine (l-Cys). The CuS nanosheets are facilely synthesized via a reductive solution route with MA as reductant and modifier at room temperature. The as-prepared CuS nanosheets have been characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), UV–vis spectra and Fourier transform infrared spectroscopy (FTIR), respectively. Experimental results indicated that formation of hydrogen bonds and thiol-Cu chemical bonds between CuS nanosheets and l-Cys significantly contributed to the sensitivity and selectivity of the proposed method no matter for RLS or visual detection of l-Cys. Under the optimum experimental conditions, the linear range of the l-Cys RLS probe was 2.78 (10σ/K)-7000nmol/L (r=0.9944), and the detection limit was 0.83nmol/L (3σ/K). As to visual detection, the detection limit could also be extended to 75μmol/L.

Consecutive Reaction to Construct Hierarchical Nanocrystalline CuS "Branch" with Tunable Catalysis Properties.

New CuS nanocrystals with a 3D hierarchical branched structure are successfully synthesized through in situ consecutive reaction method with copper foam as template. The formation mechanism of the 3D hierarchical branched structure obtained from the secondary reaction is investigated by adjusting the reaction time. The morphology of CuS nanosheet arrays with the 3D hierarchical branched structure is changed through Cu2+ exchange. In this method, the copper foam reacted completely, and the as-synthesized CuS@Cu9S5 nanocrystals are firmly grown on the surface of the 3D framework. This tunable morphology significantly influence the physical and chemical properties, particularly catalytic performance, of the materials. The as-obtained material of Cu@CuS-2 with the 3D hierarchical branched structure as catalyst for methylene blue degradation exhibits good catalytic performance than that of the material of Cu@CuS with 2D nanosheets in dark environment. Furthermore, the cation exchange between Cu and Cu2+ indicates that Cu2+ in wastewater could be absorbed by Cu@CuS-2 with the 3D hierarchical branched structure. The exchanged resultant of CuS@Cu9S5 retains its capability to degrade organic dyes. This in situ consecutive reaction method may have a significant impact on controlling the crystal growth direction of inorganic material.

Synthesis and properties of morphology controllable copper sulphide nanosheets for supercapacitor application

CuS nanosheets and their various assembled forms prepared by dealloying a Ti-Cu amorphous alloy have been investigated as electrochemical pseudocapacitor materials for energy storage applications. The properties of the assembled forms of the CuS nanosheets are determined by using the concentration of H2SO4 employed in the dealloying process. Spherical clusters composed of CuS nanosheets were fabricated by this process. These clusters have the highest specific surface areas provided by the nanosheets and exhibit high electrochemical and charge storage-release performances. The CuS spherical clusters showed a high specific capacitance of ∼276Fg−1 (at a scan rate of 5mVs−1 in cyclic voltammetry tests) and ∼713Fg−1 (at a charge-discharge current of 1.0Ag−1). The high pseudocapacitive performance can be attributed to the highest specific surface area in our case and absence of volume change of the nanosheets. These results suggest the importance of a rational nanostructure design for high-performance energy applications.

General and facile synthesis of metal sulfide nanostructures: In situ microwave synthesis and application as binder-free cathode for Li-ion batteries

Several transition metal sulfides (CuS, NiS/Ni3S2, FeS2, Co9S8) with various morphologies are in situ synthesized on the corresponding metal foils in the presence of sulfur by a facile single-mode microwave irradiation approach. The irradiation temperature is found to be a key parameter to tune product morphologies for various metal sulfides (CuS nanoparticle at 25°C; CuS nanobud at 80°C, CuS nanosheet at 140°C; NiS/Ni3S2 nanoparticle at 120°C, NiS/Ni3S2 interlinked nanosheet at 150 and 180°C, FeS2 nanoparticle at 120°C, FeS2 interlinked nanosheet at 150°C, and FeS2 nanosheet at 180°C). In general, the particle product is obtained at a low irradiation temperature, while nanosheet and interlinked porous nanosheet are obtained at higher temperatures. As a proof of concept, Cu foil supported CuS nanosheets and nanobuds are also directly used as cathode materials for lithium ion battery without addition of conductive agent and binder material. The CuS nanosheet exhibits an initial reversible capacity of 588mAhg−1 at 56mAg−1 with a small capacity fading rate of 0.17% per cycle during 100 cycles and a good high-rate capability (463mAhg−1 at 2.8Ag−1).

The Synthesis of CuS Hexagonal Nanosheet-Graphene for Use as a High Performance Photocatalyst

CuS hexagonal nanosheet/graphene was fabricated by a facile one-pot microwave-thermal method. The samples possess excellent photocatalytic activity for degradation of organic pollutant under visible light. The high photocatalytic activity was attributed to the deposition of CuS hexagonal nanosheet onto graphene. CuS nanosheet serves as a transporter which efficiently inhibits the recombination of the photo-induced charge carriers in the nanocomposites. The developed method demonstrates a facile approach towards the synthesis of two-dimensional semiconductor-graphene nanocomposites with excellent photocatalytic performance under visible light.

Fully Solution‐Processed Conductive Films Based on Colloidal Copper Selenide Nanosheets for Flexible Electronics

A novel colloidal synthesis of copper selenide nanosheets (NSs) with lateral dimensions of up to 3 μm is developed. This material is used for the fabrication of flexible conductive films prepared via simple drop‐casting of the NS dispersions without any additional treatment. The electrical performance of these coatings is benchmarked against copper selenide spherical nanocrystals (SNCs) in order to demonstrate the advantage of 2D morphology of the NSs for flexible electronics. In this contest, Cu2−xSe SNC films exhibit higher conductivity but lower reproducibility due to the formation of cracks leading to discontinuous films. Furthermore, the electrical properties of the films deposited on different flexible substrates following their bending, stretching and folding are studied. A comparison of Cu2−xSe SNC and CuSe NS films reveals an increased stability of the CuSe NS films under mechanical stress applied to the samples and their improved long‐term stability in air.