Eco-friendly synthesis and morphology-dependent superior electrocatalytic properties of CuS nanostructures

Sulfide-modified nanozerovalent iron for rapid decontamination of Cu(Ⅱ) complexes in high-salinity wastewater

Heavy metal complexes receive less attention, but they are more difficult to remove than the free heavy metals. Moreover, the high-salinity wastewaters from various industries hinder the removal of heavy metal complexes. Removal of the metal complexes is a top priority but a challenging task. Herein, a new strategy for removing Cu-EDTA from high-salinity wastewater with sulfide-modified nanozerovalent iron (S-NZVI) was proposed. The S-NZVI exhibited a considerable adsorption capacity for Cu-EDTA (∼83 mg Cu/g) at a high salt concentration (25 g/L NaCl). Similarly, the S-NZVI maintained excellent adsorption performance (∼83 mg Cu/g) in the presence of CaCl2, MgCl2, Na2SO4, and NaNO3 (25 g/L). The S-NZVI showed extremely high efficiency for Cu-EDTA removal; 50 mg/L of Cu-EDTA was almost completely removed in 1 min, and the kobs was approximately 1.5 g/(mg min). The S-NZVI showed an extensive pH working range, and within the pH range of 2-9, the Cu-EDTA was removed completely within 5 min. The excellent removal performance of the S-NZVI was due to the high reactivity and high affinity of NZVI for Cu, as well as the special substitution of Fe2+ and the interfacial reactions between S-NZVI and the copper complexes. Compared with other studies of Cu complex removal, removal with S-NZVI was a simpler process with higher efficiency. In brief, S-NZVI efficiently removed Cu complexes from harsh water environments and was reused many times. The process was simple and efficient and has broad application prospects.

Chitosan polymer matrix-derived nanocomposite (CuS/NSC) for non-enzymatic electrochemical glucose sensor

In this study, N and S co-doped chitosan polymer matrix-derived composite (CuS/NSC) was synthesized via a one-step hydrothermal technique using a low-cost copper complex of chitosan polymer. Cyclic voltammetry and chronoamperometry revealed excellent electrocatalytic performance. The glucose sensor exhibited a linear range of 160 μM to 11.76 mM, a low detection limit 2.72 μM and a sensitivity of 13.62 mA mM^-1 cm^-2 with an excellent linear response. Furthermore, the sensor also displayed selectivity for glucose over potential interfering agents and exhibited a satisfactory recovery percentage using real sample in human serum. The results demonstrate that, CuS/NSC is an efficient nanocomposite material for non-enzymatic glucose sensors and is applicable for glucose detection in biological fluids.

A high performance Pb(II) electrochemical sensor based on spherical CuS nanoparticle anchored g-C3N4

A new electrochemical sensor has been constructed for ultra-sensitive detection of lead ions (Pb²⁺) by square wave anodic stripping voltammetry (SWASV), based on the copper sulfide/graphitic carbon nitride nanocomposite modified glassy carbon electrode (CuS/g-C₃N₄/GCE). First, spherical CuS nanoparticles with good electrical conductivity were anchored on layered g-C₃N₄ with high coordination activity, affording an excellent electrode modifier CuS/g-C₃N₄ nanocomposite. Then, the performance of the CuS/g-C₃N₄/GCE and its electrochemical response to Pb²⁺ were thoroughly studied, and the sensing mechanism was investigated. On the one hand, the CuS/g-C₃N₄ nanocomposite has greatly improved the electron transportation and electrode performance through functional complementarity - CuS endows g-C₃N₄ with a good electrical conductivity and a large active specific surface area, while g-C₃N₄ endows CuS with high dispersibility and strong adsorption. On the other hand, the CuS/g-C₃N₄ modifier has effectively promoted the deposition of trace Pb²⁺ from the solution onto the electrode surface by means of synergistic enrichment (crucial for amplification of detection signals) - g-C₃N₄ can coordinate with Pb²⁺ by its large number of conjugated triazine heterocyclic rings in its molecular framework, while CuS can adsorb Pb²⁺ due to its inherent size effect of nanomaterials. The proposed sensor can efficiently detect Pb²⁺ in the concentration range of 0.050-5.000 μM with a limit of detection (LOD) as low as 4.00 nM, and can be well applied for the detection of trace Pb²⁺ in actual tea samples.

Non-Enzymatic Glucose Sensors Involving Copper: An Electrochemical Perspective

Non-enzymatic glucose sensors based on the use of copper and its oxides have emerged as promising candidates to replace enzymatic glucose sensors owing to their stability, ease of fabrication, and superior sensitivity. This review explains the theories of the mechanism of glucose oxidation on copper transition metal electrodes. It also presents an overview on the development of among the best non-enzymatic copper-based glucose sensors in the past 10 years. A brief description of methods, interesting findings, and important performance parameters are provided to inspire the reader and researcher to create new improvements in sensor design. Finally, several important considerations that pertain to the nano-structuring of the electrode surface is provided.

Waste eggshell membrane-templated synthesis of functional Cu2+-Cu+/biochar for an ultrasensitive electrochemical enzyme-free glucose sensor

A fast and sensitive test of blood glucose levels is very important for monitoring and reducing diabetic complications. Herein, a simple and sensitive non-enzymatic glucose sensing platform was fabricated by employing Cu²⁺–Cu⁺/biochar as the catalyst. The Cu²⁺–Cu⁺/biochar was synthesized through a bio-inspired synthesis, in which waste eggshell membrane (ESM) was introduced as a template to absorb Cu²⁺, then converting it into Cu²⁺–Cu⁺ biochar via a rapid pyrolysis. The structure and properties of the as-prepared Cu²⁺–Cu⁺ biochar were determined by scanning electron microscopy (SEM), FT-IR spectroscopy, Raman spectroscopy and cyclic voltammetry (CV). Due to great advantages of Cu²⁺–Cu⁺/biochar, such as high electrical conductivity, unique three-dimensional porous network and large electrochemically active surface area, the as-prepared Cu²⁺–Cu⁺ biochar modified electrode showed high catalytic activity towards glucose oxidization. The fabricated enzyme-free glucose sensor showed excellent performance for glucose determination with a linear range of 12.5–670 μM, and a limit of detection (LOD) of 1.04 μM. Moreover, the as-fabricated sensor has good anti-interference ability and stability. Finally, the proposed senor has been successfully applied to detect glucose in clinical samples (human serum). Owing to the green synthesis method, using biowaste ESM as a template, and the superior catalytic performance and low cost of Cu²⁺–Cu⁺/biochar, the developed sensor shows great potential in clinical applications for direct sensing of glucose.

The fabrication process of the nonenzyme glucose sensing based Cu²⁺–Cu⁺/biochar.

Electrochemical Enzyme-free Sensing of Oxalic Acid Using an Amine-mediated Synthesis of CuS Nanosphere

Copper sulfide nanospheres (CuS NS) were prepared by a solvothermal method with the support of p-phenylene diamine as a structure direct agent. The formation of CuS NS was evaluated using XRD, FE-SEM, HR-TEM, XPS, and electrochemical methods. The CuS NS modified electrode demonstrated excellent electro-catalytic behavior for the electro-oxidation of oxalic acid (OA). The modified electrode showed a good linear range (50 to 700 μM), high sensitivity (0.0353 μA μM^-1 cm^-2), a low detection limit (35.6 μM), long term stability and good anti-interference behavior.

Design of Double-Shelled CuS Nanocages to Optimize Electrocatalytic Dynamic for Sensitive Detection of Ascorbic Acid

Although transition metal sulfides have presented prospect in electrochemical sensing, their electrocatalytic performance still cannot meet the demands for practical applications due to the difficulties in mass transport and electron transfer. In this work, double-shelled CuS nanocages (2-CuS NCs) were prepared for enzyme-free ascorbic (AA) sensor through a Cu2O- templated method. The unique double-shelled hollow structure displayed large specific surface areas, ordered diffusion channels, increased volume occupying rate, and accelerated electron transfer rate, resulting in enhanced electrochemical dynamic. As a sensing electrode for AA, 2-CuS NCs modified glassy carbon electrode (2-CuS NCs/GCE) exhibited eminent electrocatalytic activity in terms of satisfying sensitivity (523.7 μA mM-1 cm-2), short response time (0.31 s), and low limit of detection (LOD, 0.15 μM). 2-CuS NCs look promising for analytical sensing of AA in electrochemical sensors thanks to its prominent electrocatalytic kinetics issued from double-shelled hollow porous structure.

Designing novel morphologies of l-cysteine surface capped 2D covellite (CuS) nanoplates to study the effect of CuS morphologies on dye degradation rate under visible light

Novel CuS@l-Cys NPs are designed by a hydrothermal route. The effects of synthetic parameters on the morphologies of CuS@l-Cys NPs were investigated. CuS@l-Cys NPs exhibit an enhanced dye degradation rate under visible light.

Cu-Deficient plasmonic Cu2−xS nanocrystals induced tunable photocatalytic activities

Cu-Deficient plasmonic Cu_2−xS nanocrystals with tunable photocatalytic activities were synthesized and investigated.

Highly sensitive determination of L-tyrosine in pig serum based on ultrathin CuS nanosheets composite electrode

Nanometer-sized copper sulfide has remarkable properties such as metal like electrical conductivity and electrocatalytic activity. In this work, ultrathin copper sulfide nanosheets (CuS NS) were synthesized and employed to modify on surface of glassy carbon electrode (GCE) combining with chitosan (CS) and acidified multi-walled carbon nanotubes (F-MWCNTs). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the shape of CuS NS was hexagon with side length of 13.33 ± 0.67 nm and thickness of 4.50 ± 0.58 nm. The electrochemical characteristics of different nanocomposite modified electrodes were examined by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), indicating that the modified electrode of CuS NS-CS/F-MWCNTs/GCE possessed good electrocatalytic activity towards oxidation of L-tyrosine (L-Tyr). Under the optimal condition, the modified electrode exhibited a wide linear response range for L-Tyr (0.08-1.0 μM) with a detection limit of 4.9 nM. No obvious interferences from coexisted two-fold of L-tryptophan and 50-fold of other amino acids could be observed, indicating its relatively good selectivity. The electrode also had good repeatability, reproducibility and stability. Compared with a commercial instrument analytical method, HPLC, the electrode can be successfully applied to the determination of L-Tyr in pig serums with a recovery rate of 95.7%-102.6%, and its test results are in good agreement with that of HPLC, showing its promising application value.

3D-Flower-Like Copper Sulfide Nanoflake-Decorated Carbon Nanofragments-Modified Glassy Carbon Electrodes for Simultaneous Electrocatalytic Sensing of Co-existing Hydroquinone and Catechol

A copper sulfide nanoflakes-decorated carbon nanofragments-modified glassy carbon electrode (CuS-CNF/GCE) was fabricated for the electrocatalytic differentiation and determination of hydroquinone (HQ) and catechol (CC). The physicochemical properties of the CuS-CNF were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The electrocatalytic determination of HQ and CC over the CuS-CNF/GCE was evaluated by cyclic voltammetry and differential pulse voltammetry. An excellent detection limit and sensitivity of the CuS-CNF/GCE are obtained (0.293 µM and 0.259 µM) with a sensitivity of 184 nA µM⁻¹ cm⁻² and 208 nA µM⁻¹ cm⁻² (S/N=3) for HQ and CC, respectively. In addition, the CuS-CNF/GCE shows a selective identification of HQ and CC over potential interfering metal ions (Zn²⁺, Na⁺, K⁺, NO³⁻, SO₄²⁻, Cl⁻) and organic compounds (ascorbic acid, glucose), and a satisfactory recovery is also obtained in the spiked water samples. These results suggest that the CuS-CNF/GCE can be used as an efficient electrochemical sensor for the simultaneous determination of co-existing environmental pollutants such as HQ and CC in water environments with high selectivity and acceptable reproducibility.

Supercapacitive properties of amorphous MoS3 and crystalline MoS2 nanosheets in an organic electrolyte

Amorphous-MoS₃ and crystalline-MoS₂ prepared via thermal decomposition of ammonium tetrathiomolybdate and their electrochemical energy-storage properties reveals better capacitive and charge-transfer nature for MoS₂ SSC over amorphous-MoS₃ SSC.

Oleylamine-Mediated Hydrothermal Growth of Millimeter-Long Cu Nanowires and Their Electrocatalytic Activity for Reduction of Nitrate

While high-aspect-ratio metal nanowires are essential for producing nanowire-based electrodes of good performance used in electronics and electrocatalysis, the synthesis of millimeter-long Cu nanowires remains a challenge. This work demonstrates an oleylamine-mediated hydrothermal method for synthesis of Cu nanowires with an average diameter of ~80 nm and a length up to several millimeters. An investigation on the role of oleylamine in nanowire formation by mass spectroscopy, small angle X-ray diffraction and transmission electron microscopy reveals that oleylamine serves as a mild reducing agent for slow reduction of Cu(II) to Cu, a complexing agent to form Cu(II)-oleylamine complex for guiding the nanowire growth, as well as a surfactant to generate lamellar phase structure for the formation of nanowire bundles. The growth mechanism of these millimeter-long Cu nanowire bundles is proposed based on the experimental observations. Electrochemical measurements by linear sweep voltammetry indicate that the self-supported nanowire electrode prepared from as-formed Cu nanowire bundles shows high catalytic activity for electroreduction of nitrate in water.

The Facile Synthesis of Branch-Trunk Ag Hierarchical Nanostructures and Their Applications for High-Performance H₂O₂ Electrochemical Sensors

A novel branch-trunk Ag hierarchical nanostructure was synthesized via a galvanic replacement reaction combined with microwave-assisted synthesis using Te nanowire as a sacrificial template. The Te nanowire was synthesized via a hydrothermal process. We further investigated the potential application of the obtained hierarchical nanostructures in electrochemical sensor analysis. The results showed that the as-prepared sensor exhibited a wide linear range with 0.05 µM to 1.925 mM (R = 0.998) and the detection limit was estimated to be 0.013 µM (S/N = 3). These results indicate the branch-truck Ag hierarchical nanostructures are an excellent candidate material for sensing applications.