Advantageous Effects of Phase Transition-Modulated Electric Polarization of Hollow CuSx for Enhanced Electromagnetic Wave Absorption

Scrutinizing the electromagnetic wave absorption mechanism of sulfides remains a challenge due to the variability of the modulation of the crystal structure of the sulfides. To take advantage of this variability, nanosheet-assembled Cu9S5/CN composites with sulfur vacancies were prepared in this study by self-assembly synthesis and subsequent high-temperature heat treatment. Systematic studies show the phase transition-dependent induced decrease in the conductivity, the defect site-induced difference in the charge density, the weakened vacancy formation of defect polarization loss, and the influence of valence state on electric dipole polarization loss and interfacial polarization loss, making the optimization of the dielectric constant a significant positive effect on the improvement of impedance matching. This work provides a reliable example and theoretical guidance for the crystal structure design for the preparation of a new generation of efficient sulfide-based wave-absorbing materials.

Application of Copper-Sulfur Compound Electrode Materials in Supercapacitors

Supercapacitors (SCs) are a novel type of energy storage device that exhibit features such as a short charging time, a long service life, excellent temperature characteristics, energy saving, and environmental protection. The capacitance of SCs depends on the electrode materials. Currently, carbon-based materials, transition metal oxides/hydroxides, and conductive polymers are widely used as electrode materials. However, the low specific capacitance of carbon-based materials, high cost of transition metal oxides/hydroxides, and poor cycling performance of conductive polymers as electrodes limit their applications. Copper-sulfur compounds used as electrode materials exhibit excellent electrical conductivity, a wide voltage range, high specific capacitance, diverse structures, and abundant copper reserves, and have been widely studied in catalysis, sensors, supercapacitors, solar cells, and other fields. This review summarizes the application of copper-sulfur compounds in SCs, details the research directions and development strategies of copper-sulfur compounds in SCs, and analyses and summarizes the research hotspots and outlook, so as to provide a reference and guidance for the use of copper-sulfur compounds.

Mechanochemical synthesis of non-stoichiometric copper sulfide Cu1.8S applicable as a photocatalyst and antibacterial agent and synthesis scalability verification

An effort to prepare different non-stoichiometric Cu_xS_y compounds starting from elemental precursors using mechanochemistry was made in this study. However, out of the 7 stoichiometries tested, it was only possible to obtain three phases: covellite CuS, chalcocite Cu₂S and digenite Cu_1.8S and their mixtures. To obtain the digenite phase with the highest purity, the Cu : S stoichiometric ratio needed to be fixed at 1.6 : 1. The reaction between copper and sulfur was completed within a second range, however, milling was performed for up to 15 minutes until the equilibrium in phase composition between digenite and covellite was reached. The possibility of preparing the product in a 300 g batch by eccentric vibratory milling in 30 minutes was successfully verified at the end. The estimated crystallite sizes for the digenite Cu_1.8S obtained via lab-scale and scalable experiments were around 12 and 17 nm, respectively. The obtained products were found to be efficient photocatalysts under visible light irradiation in the presence of hydrogen peroxide, being capable of the complete degradation of the Methyl Orange dye in a concentration of 10 mg L^-1 in 2 hours. Finally, the antibacterial potential of both lab-scale and large-scale industrial products was proven and, regardless of the manufacturing scale, the nanoparticles retained their properties against bacterial cells.

Cuprous or cupric? How substrate polarity can select for different phases of copper sulfide films in chemical bath deposition

Copper sulfides have many applications from thermoelectrics to biotechnology. While the properties of different copper sulfide phases are well understood, controlling the deposited copper sulfide stoichiometry remains a significant challenge, especially in solution-phase synthesis techniques. In this work, we investigate the chemical bath deposition of Cu_xS on functionalized self-assembled monolayers (SAMs). Time-of-flight mass spectrometry, Raman spectroscopy, and x-ray photoelectron spectroscopy are employed to analyze the deposited films. We show that the use of thiourea as a sulfur source leads to the deposition of different copper sulfide phases and is controlled by the interaction of sulfur-containing ions in solution with the functionalized SAMs. For -COOH terminated SAMs, copper sulfide deposition is controlled by the surface polarity of the substrate. At the bath pH used in these experiments, the -COOH terminal groups are deprotonated. The resulting -COO^- terminated SAM surface repels negatively charged sulfur-containing ions, leading to the deposition of Cu₂S. For -CH₃ terminated SAMs, which are non-polar, there is no specific interaction between the SAM terminal group and sulfur-containing ions and CuS is deposited. For -OH terminated SAMs, which have a polar terminal group, there are two competing effects: the repulsion of S-containing ions by the small negative charge of the terminal -OH group and the increase in the concentration of sulfur-containing ions in solution as the bath pH increases. This competition leads to the deposit stoichiometry changing from Cu₂S at pH 9 to CuS at pH 12.

Microbial synthesis of Cu7S4/rGO nanocomposites with efficient photocatalytic activity for the degradation of methyl green

Cu₇S₄/reduced graphene oxide (rGO) photocatalysts are attracting increasing interest because of their low cost and environmental friendliness.

Efficient and stable catalysis of hollow Cu9S5 nanospheres in the Fenton-like degradation of organic dyes

The development of new heterogeneous catalysts with stable catalytic activity in a wide pH range to prevent polluting precipitation plays a vital role in large-scale wastewater treatment. Here, a facile anion exchange strategy was designed to fabricate hollow Cu₉S₅ nanospheres by using Cu₂O nanospheres as hard-templates. The structural and compositional transformation from Cu₂O nanospheres to hollow Cu₉S₅ nanospheres were investigated via X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The Fenton-like degradation of organic dyes was used to evaluate the catalytic performance of the obtained Cu-containing catalysts. Results reveal that the hollow Cu₉S₅ nanospheres have the best catalytic activity among five kinds of Cu-containing catalysts. Hollow Cu₉S₅ nanospheres can effectively accelerate the decomposition of H₂O₂ into hydroxyl radicals and superoxide radical, which have been proven to be mainly oxidative species in the Fenton-like degradation of organic pollutants. Hollow Cu₉S₅ nanospheres have a wide pH application range of 5.0-9.0, and their extremely stable activity can be maintained in at least 15 catalytic cycles with a Cu²⁺ ion leaching rate of less than 1.0 %. The outstanding catalytic performance of the Cu₉S₅ catalyst is expected to enhance the practical applications of copper sulfide catalysts in Fenton-like wastewater treatment.

Metal–organic framework templated fabrication of Cu7S4@Ni(OH)2 core–shell nanoarrays for high-performance supercapacitors

Core–cell Cu₇S₄@Ni(OH)₂ nanorod arrays were fabricated by using metal–organic frameworks as templates, and showed high specific capacitance, superior rate capacity and excellent cycling stability for supercapacitors.

One-pot synthesis of ZnS nanowires/Cu7S4 nanoparticles/reduced graphene oxide nanocomposites for supercapacitor and photocatalysis applications

ZnS nanowires/Cu₇S₄ nanoparticles/rGO nanocomposites were fabricated as photocatalysts and supercapacitor electrodes for the first time.

Dataset analysis on Cu9S5 material structure and its electrochemical behavior as anode for sodium-ion batteries

The data presented in this data article are related to the research article entitled "Facile Synthetic Strategy to Uniform Cu₉S₅ Embedded into Carbon: A Novel Anode for Sodium-Ion Batteries" (Jing et al., 2018) [1]. The related experiment details of pure Cu₉S₅ has been stated. The structure data of pure Cu₉S₅ and the electrochemical performance for sodium-ion batteries are described.

The synthesis of core–shell Cu9S5@mSiO2–ICG@PEG–LA for photothermal and photodynamic therapy

A Cu₉S₅@mSiO₂–ICG@PEG–LA core–shell nanocomposite was synthesized to integrate NIR-modulated PTT and PDT, revealing enhanced cytotoxicity to the HepG2 cell.

Diversified copper sulfide (Cu2-xS) micro-/nanostructures: a comprehensive review on synthesis, modifications and applications

As a significant metal chalcogenide, copper sulfide (Cu_2-xS, 0 < x < 1), with a unique semiconducting and nontoxic nature, has received significant attention over the past few decades. Extensive investigations have been employed to the various Cu_2-xS micro-/nanostructures owing to their excellent optoelectronic behavior, potential thermoelectric properties, and promising biomedical applications. As a result, micro-/nanostructured Cu_2-xS with well-controlled morphologies, sizes, crystalline phases, and compositions have been rationally synthesized and applied in the fields of photocatalysis, energy conversion, in vitro biosensing, and in vivo imaging and therapy. However, a comprehensive review on diversified Cu_2-xS micro-/nanostructures is still lacking; therefore, there is an imperative need to thoroughly highlight the new advances made in function-directed Cu_2-xS-based nanocomposites. In this review, we have summarized the important progress made in the diversified Cu_2-xS micro-/nanostructures, including that in the synthetic strategies for the preparation of 0D, 1D, 2D, and 3D micro-/nanostructures (including polyhedral, hierarchical, hollow architectures, and superlattices) and in the development of modified Cu_2-xS-based composites for enhanced performance, as well as their various applications. Furthermore, the present issues and promising research directions are briefly discussed.

Self-template synthesis of hollow ellipsoid Ni–Mn sulfides for supercapacitors, electrocatalytic oxidation of glucose and water treatment

Hollow ellipsoid Ni–Mn sulfides have been successfully synthesized via a simple self-template method and exhibited good performance in supercapacitors, electrocatalytic oxidation of glucose and water treatment.

A novel sandwich-type immunosensor based on three-dimensional graphene–Au aerogels and quaternary chalcogenide nanocrystals for the detection of carcino embryonic antigen

Cu₂ZnSnS₄ nanocrystals were firstly used as electrocatalysts in H₂O₂ reduction for ultrasensitive detection of carcino embryonic antigen.

Interconnected CuS nanowalls with rough surfaces grown on nickel foam as high-performance electrodes for supercapacitors

Three-dimensional interconnected CuS nanowalls with rough surfaces on Ni foam were obtained through a facial ​ synthetic route. The binder-free electrode exhibits high electrochemical performance with excellent cycling stability.

Understanding the roles of metal sources and dodecanethiols in the formation of metal sulfide nanocrystals via a two-phase approach

We present a two-phase approach for controllable synthesis of metal sulfide nanocrystals, such as Cu_2−xS, Ag₂S and Ni₉S₈, in which the reaction takes place at the water/oil interface.

Comparison of NiS2 and α-NiS hollow spheres for supercapacitors, non-enzymatic glucose sensors and water treatment

NiS₂ and α-NiS hollow spheres are prepared via a template-free method. When NiS₂ and α-NiS hollow spheres were evaluated for supercapacitors, glucose sensors and water treatment, it was found that the hollow α-NiS spheres exhibited better performance than the NiS₂.