Search Results (591)

A series of Cu-MnO_x/GF catalytic electrodes, with graphite felt (GF) pretreated via microwave modification as the catalyst carrier, were prepared under various hydrothermal conditions and characterized using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, and Raman spectroscopy. The catalytic oxidation activity of catalytic Cu-MnO_x/GF electrodes toward toluene was evaluated in an all-solid-state electrocatalytic device under mild operating conditions. The evaluation results demonstrated that the microwave-modified catalytic electrode exhibited high electrocatalytic activity toward toluene oxidation, with Cu-MnO_x/700W-GF exhibiting significantly higher catalytic activity, indicating that an increase in catalyst loading capacity can promote the removal of toluene. Only CO₂ and CO were detected, with no other intermediates observed in the reaction process. Moreover, the catalytic effect was significantly affected by the relative humidity. The catalytic oxidation of toluene can be fully realized under a certain humidity, indicating that the conversion of H₂O to strongly oxidizing ·OH on the catalytic electrode is a key step in this reaction. Full article

Rouaite (Cu₂(OH)₃NO₃) long hexagonal multilayered nanoplates with high purity and high crystallinity were prepared from acidic reaction solution (pH = 4.4–4.8) with the assistance of ZnO. The ZnO-assisted strategy is remarkably different from the conventional synthetic protocol that was regularly carried out in alkaline solution (pH > 11). The rouaite multilayer nanoplates displayed exceptionally high catalytic activity in the catalytic wet peroxide oxidation (CWPO) of Congo red (CR). The catalytic efficiency for CR decolorization achieved an impressive 96.3% in 50 min under near-neutral (pH = 6.76) and ambient conditions (T = 20 °C, p = 1 atm), without increasing the temperature and/or decreasing the pH value to acidic region (pH = 2–3) as is commonly employed in CWPO process for improved degradation efficiency. Full article

Environmental sustainability and responsible resource utilization are critical global challenges. In this work, we present a sustainable and circular-economy-based approach for synthesizing CuFe₂O₄ nanoparticles by directly utilizing copper oxide minerals sourced from Chilean mining operations. Copper sulfate (CuSO₄) was extracted from these minerals through acid leaching and used as a precursor for nanoparticle synthesis via both chemical co-precipitation and microwave-assisted methods. The influence of different precipitating agents—NaOH, Na₂CO₃, and NaF—was systematically evaluated. XRD and FESEM analyses revealed that NaOH produced the most phase-pure and well-dispersed nanoparticles, while NaF resulted in secondary phase formation. The microwave-assisted method further improved particle uniformity and reduced agglomeration due to rapid and homogeneous heating. Electrochemical characterization was conducted to assess the suitability of the synthesized CuFe₂O₄ for supercapacitor applications. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements confirmed pseudocapacitive behavior, with a specific capacitance of up to 1000 F/g at 2 A/g. These findings highlight the potential of CuFe₂O₄ as a low-cost, high-performance electrode material for energy storage. This study underscores the feasibility of converting primary mined minerals into functional nanomaterials while promoting sustainable mineral valorization. The approach can be extended to other critical metals and mineral residues, including tailings, supporting the broader goals of a circular economy and environmental remediation. Full article

In this study, 3-chlorothiophene-2-carboxylic acid (HL) was used as a main ligand to successfully synthesize four novel complexes: [Cu(L)₂(Py)₂(OH₂)₂] (1), [Co(L)₂(Py)₂(OH₂)₂] (2) (Py = pyridine), [{Ni(L)₂(OH₂)₄}₂{Ni(L)(OH₂)₅}]L•5H₂O (3), and [{Co(L)₂(OH₂)₄}₂{Co(L)(OH₂)₅}]L•5H₂O (4). All four compounds were identified by elemental analysis and ESI mass spectrometry, and subsequently characterized by IR spectroscopy, UV-visible diffuse reflectance spectroscopy, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography, and cyclic voltammetry. X-ray analyses revealed that complexes 1 and 2 exhibit a centrosymmetric pseudo-octahedral coordination geometry; the copper (II) and cobalt (II) metal ions, respectively, are located at the crystallographic center of inversion. The coordination sphere of the copper (II) complex is axially elongated in accordance with the Jahn–Teller effect. Intriguingly, for charge neutrality, compounds 3 and 4 crystallized as three independent mononuclear octahedrally coordinated metal centers, which are two $\left[\mathrm{M}{\mathrm{L}}_2{\left({\mathrm{O}\mathrm{H}}_2\right)}_4\right]$ complex molecules and one ${\left[\mathrm{M}\mathrm{L}{\left({\mathrm{O}\mathrm{H}}_2\right)}_5\right]}^{+}$ complex cation (M = ${\mathrm{N}\mathrm{i}}^{\mathrm{I}\mathrm{I}}$ and ${\mathrm{C}\mathrm{o}}^{\mathrm{I}\mathrm{I}}$, respectively), with the ligand anion ${\mathrm{L}}^{-}$ serving as the counter ion. The anticancer activities of these complexes were systematically assessed on human leukemia K562 cells, lung cancer A549 cells, liver cancer HepG2 cells, breast cancer MDA-MB-231 cells, and colon cancer SW480 cells. Among them, complex 4 shows significant inhibitory effects on leukemia K562 cells and colon cancer SW480 cells. Full article

In this study, we investigate the optical and structural properties of Cu-doped β-Ga₂O₃ nanostructures synthesized via a hydrothermal method, followed by annealing in ambient O₂. Different Cu doping concentrations (0, 1.6, and 4.8 at.%) are introduced to examine their effects on the crystal structure, chemical state, and optical bandgap of β-Ga₂O₃. X-ray diffraction (XRD) analysis reveals that the host β-Ga₂O₃ crystal structure is preserved at lower doping levels, whereas secondary phases (Ga₂CuO₄) appear at higher doping concentrations (4.8 at.%). X-ray photoelectron spectroscopy (XPS) confirms the presence of Cu²⁺ ions in both lattice substitution sites and surface-adsorbed hydroxylated species (Cu(OH)₂). The optical bandgap of β-Ga₂O₃ is found to decrease with increasing Cu concentration, likely due to the formation of localized states or secondary phases. These findings demonstrate the tunability of the optical properties of β-Ga₂O₃ via Cu doping, providing insights into the incorporation mechanisms and their impact on structural and electronic properties. Full article

Free-standing copper oxide (Cu₂O)-copper hydroxide (Cu(OH)₂) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)₂@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm², achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu₂O-Cu(OH)₂@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes. Full article

A facile fabrication method was developed for the growth of Cu_1.8Se nanosheets (NSs) on a Cu foil substrate, enabling dual-functionality as an electrochemical sensor for H₂O₂ and an active surface-enhanced Raman scattering (SERS) substrate. The process involved the preparation of Cu(OH)₂ nanowires (NWs) via electrochemical oxidation, followed by chemical conversion to Cu_1.8Se through a selenization process. The morphology, composition, and microstructure of the resulting Cu_1.8Se NSs were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Cu_1.8Se NSs exhibited excellent electrocatalytic activity for H₂O₂ reduction, achieving a notably low detection limit of 1.25 μM and demonstrating rapid response and high sensitivity with a linear relationship in amperometric detection. Additionally, SERS experiments using Rhodamine B as a probe molecule and the Cu_1.8Se NS/Cu foil as a substrate displayed outstanding performance, with a detection limit as low as 1 μM. The flower-like structure of the Cu_1.8Se NSs exhibited linear dependence between analyte concentration and detection signals, along with satisfactory reproducibility in dual-sensing applications. These findings underscore the scalability and potential of this fabrication approach for advanced sensor development. Full article

Pharmaceuticals such as diclofenac (DCF), a widely used anti-inflammatory drug, are frequently detected in water bodies and pose serious environmental and health risks due to their persistence and low biodegradability. Although ozonation is an effective method for pollutant removal, its efficiency is often limited by low ozone utilization and incomplete mineralization. In this work, CuO/Al₂O₃- and MnO₂/Al₂O₃-supported catalysts were prepared via an impregnation method and evaluated for their performance in catalytic ozonation of diclofenac (DCF) in an aqueous solution. The catalysts were characterized by TEM, N₂ adsorption–desorption, FTIR, and XPS analyses. The effects of catalyst type, dosage, initial pH, and ozone flow rate on degradation efficiency were systematically investigated. Under optimal conditions, the DCF removal efficiencies reached 73.99% and 76.33% using CuO/Al₂O₃ and MnO₂/Al₂O₃, respectively, while COD removal efficiencies were 77.6% and 89.3%. Quenching experiments indicated that hydroxyl radicals (•OH) were the predominant reactive species involved in the catalytic ozonation process. The results demonstrate that supported CuO and MnO₂ catalysts can effectively enhance diclofenac degradation by ozone, offering potential for advanced water treatment applications. Full article

The corrosion behaviors of newly developed solder alloys with excellent mechanical properties, Sn-2.5 Ag-1.0 Bi-0.8 Cu-0.05 Ni (SABC25108N) and Sn-1.5 Bi-0.75 Cu-0.065 Ni (SBC15075N), are analyzed to supplement the corrosion behavior of the limited corrosion data in Pb- and Zn-free solder compositions. A potentiodynamic polarization test is conducted on these compositions in a NaCl electrolyte solution, the results of which are compared with those of conventional Sn-3.0 (wt%) Ag-0.5Cu and Sn-1.2Ag-0.5Cu-0.05Ni alloys. The results indicate that SBC15075N exhibits the lowest corrosion potential and highest corrosion current density, thus signifying the lowest corrosion resistance. By contrast, SABC25108N exhibits the lowest corrosion current density and highest corrosion resistance. Notably, SABC25108N shows a slower corrosion progression in the active state and exhibits the longest passive state. The difference in corrosion resistance is affected more significantly by the formation and distribution of the Ag₃Sn intermetallic compound phase owing to the high Ag content instead of by the presence of Bi or Ni. This uniform dispersion of Ag₃Sn IMC phases in the SABC25108N alloy effectively suppressed corrosion propagation along the grain boundaries and reduced the formation of corrosion products, such as Sn₃O(OH)₂Cl₂, thereby enhancing the overall corrosion resistance. These findings provide valuable insights into the optimal design of solder alloys and highlight the importance of incorporating sufficient Ag content into multicomponent compositions to improve corrosion resistance. Full article

The increasing global demand for copper has driven the search for more efficient and sustainable extraction methods, particularly due to the environmental concerns associated with conventional processes. This study investigated the leaching of copper minerals MC (Cu₂O) and malachite (Cu₂CO₃(OH)₂) using glycine as an organic ligand in an alkaline medium, and evaluated the efficiency of hydrogen peroxide (H₂O₂) and ozone (O₃) as oxidizing agents. Chemical and mineralogical characterization using XRD, XRF, ICP, and SEM confirmed the predominance of MC and malachite, along with secondary phases such as hematite and calcite. Leaching experiments were carried out by varying glycine and oxidant concentrations at pH 10, with a reaction time of 240 min, agitation at 800 min⁻¹, a solution volume of 300 mL, and a mineral sample concentration of 0.33 g·L⁻¹. The results showed that O₃ exhibited low efficiency due to its limited solubility, whereas H₂O₂ achieved dissolution rates of 69.7% for MC in 150 min and 96.3% for MMin just 60 min. The glycine-H₂O₂ system optimized reaction time by 84% compared to conventional methods, emerging as a sustainable alternative due to the low toxicity and biodegradability of glycine. Full article

Investigating viable processes for the use of lignocellulosic biomass in clean fuels and high-value-added chemical products is essential for sustainable development. Large amounts of lignin are available every year as by-products of the paper and biorefinery industries, causing a series of problems, particularly environmental ones. Its structure and composition make lignin compatible with the concept of sustainability, since it can be used to produce new chemical products with high added value. As such, this study aims to extract lignin from green coconut fiber (LIG), with the subsequent impregnation of a sodium-octanoate-based surfactant (LIG-SUR), and determine its applicability as an adsorbent for removing copper ions from synthetic waste. To this end, the green coconut fiber lignocellulosic biomass was initially subjected to alkaline pre-treatment with 2% (w/v) sodium hydroxide in an autoclave. Next, the surface of the lignin was modified by impregnating it with sodium octanoate, synthesized from the reaction of octanoic acid and NaOH. The physical and chemical traits of the lignin were studied before and after surfactant impregnation, as well as after copper ion adsorption. The lignin was analyzed by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The adsorption tests were carried out using lignin pre-treated with surfactant in a batch system, where the effects of pH and adsorbent concentration were investigated. XRF and SEM analyses confirmed surfactant impregnation, with Na₂O partially replaced by CuO after Cu²⁺ adsorption. FTIR analysis revealed shifts in O–H, C–H, C=O, and C=C bands, indicating electrostatic interactions with lignin. Adsorption kinetics followed the pseudo-second-order model, suggesting chemisorption, with equilibrium reached in approximately 10 and 60 min for LIG-SUR and LIG, respectively. The Langmuir model best described the isotherm data, indicating monolayer adsorption. LIG-SUR removed 91.57% of Cu²⁺ and reached a maximum capacity of 30.7 mg·g⁻¹ at 25 °C and a pH of 6. The results of this research showed that pre-treatment with NaOH, followed by impregnation with surfactant, significantly increased the adsorption capacity of copper ions in solution. This technique is a viable and sustainable alternative to the traditional adsorbents used to treat liquid waste. In addition, by using green coconut fiber lignin more efficiently, the research contributes to adding value to this material and strengthening practices in line with the circular economy and environmental preservation. Full article

Electrocatalytic nitrate reduction reaction (NO₃⁻RR) to ammonia (NH₃) presents an alternative, sustainable approach to ammonia production. However, the existing catalysts suffer from poor NH₃ yield under lower concentrations of NO₃⁻, and the kinetic understanding of bimetal catalysis is lacking. In this study, a Co₃O₄–modified Cu₂₊₁O nanowire (CoCuNWs) catalyst with a high specific surface area was synthesized to effectively produce NH₃ from a 10 mM KNO₃ basic solution. CoCuNWs demonstrated a high NH₃ yield rate of 0.30 mmol h⁻¹ cm⁻² with an NH₃ Faradaic efficiency (FE) of 96.7% at −0.2 V vs. RHE, which is 1.5 times higher than the bare Cu₂₊₁O NWs. The synergistic effect between Co₃O₄ and Cu₂₊₁O significantly enhanced both the nitrate conversion and ammonia yield. Importantly, it is revealed that the surface of CoCuNWs is kinetically more easily saturated with NO₃⁻ (NO₂⁻) ions than that of Cu₂₊₁O NWs, as evidenced by both the higher current density and the plateau occurring at higher NO_x⁻ concentrations. In addition, CoCuNWs exhibit a higher diffusion coefficient of NO₃⁻, being 1.6 times higher than that of Cu₂₊₁O NWs, which also indicates that the presence of Co₃O₄ could promote the diffusion and adsorption of NO₃⁻ on CoCuNWs. Moreover, the ATR–SEIRAS analysis was applied to illustrate the reduction pathway of NO₃⁻ to NH₃ on CoCuNWs, which follows the formation of the key intermediate from *NO₂⁻, *NO, *NH₂OH to *NH₃. This work presents a strategy for constructing dual–metal catalysts for NO₃⁻RR and provides an insight to understand the catalysis from the perspective of the kinetics. Full article

Copper-thiolate nanostructures, formed through the self-assembly of cysteine (Cys) and glutathione (GSH) with copper ions, offer a versatile platform for redox-active applications due to their structural stability and chemical functionality. In this study, Cu-Cys-GSH nanoparticles were synthesized and employed to develop a capacitive biosensor for the ultralow concentration detection of hydrogen peroxide (H₂O₂). The detection mechanism leverages a Fenton-like reaction, where H₂O₂ interacts with Cu-Cys-GSH nanoparticles to generate hydroxyl radicals (·OH) through redox cycling between Cu²⁺ and Cu⁺ ions. These redox processes induce changes in the sensor’s surface charge and dielectric properties, enabling highly sensitive capacitive sensing at gold interdigitated electrodes (IDEs). The influence of chirality on sensing performance was investigated by synthesizing nanoparticles with both L- and D-cysteine enantiomers. Comparative analysis revealed that the stereochemistry of cysteine impacts the catalytic activity and sensor response, with Cu-L-Cys-GSH nanoparticles exhibiting superior performance. Specifically, the biosensor achieved a linear detection range from 1.0 fM to 1.0 pM and demonstrated an ultra-sensitive detection limit of 21.8 aM, outperforming many existing methods for H₂O₂ detection. The sensor’s practical performance was further validated using milk and saliva samples, yielding high recovery rates and confirming its robustness and accuracy for real-world applications. This study offers a disposable, low-cost sensing platform compatible with sustainable healthcare practices and facilitates easy integration into point-of-care diagnostic systems. Full article

The low-dimensional metal halide Cs₃Cu₂I₅ exhibits unique electrical and chemical properties. Notably, it undergoes a phase transition to CsCu₂I₃ upon exposure to hydroxyl (-OH) gas, resulting in significant changes in its electrical characteristics. In this study, we developed a highly selective semiconductor-based gas sensor utilizing Cs₃Cu₂I₅. The material was synthesized on an Al₂O₃ substrate with carbon electrodes using a solution-based process, enabling gas sensing based on its electrical properties. The sensor was further integrated into an Arduino-based real-time monitoring system for wearable applications. The final system was mounted onto a face mask, enabling the real-time detection of human respiration. This research presents a next-generation sensor platform for real-time respiratory monitoring, demonstrating the potential of Cs₃Cu₂I₅ in advanced wearable bio-gas sensing applications. Full article

This study addresses energy transition challenges through the development of NiCuCe catalysts for high-purity hydrogen production via methanol decomposition, with carbon deposition issues mitigated by CO₂-assisted regeneration. As fossil fuel depletion advances and the urgency of climate change increases, methanol-derived hydrogen (CH₃OH → CO + 2H₂) emerges as a carbon-neutral alternative to conventional fossil fuel-based energy systems. The catalyst’s dual Cu²⁺/Ni²⁺ active sites facilitate selective C–O bond cleavage, achieving more than 80% methanol conversion at temperatures exceeding 280 °C without the need for fossil methane inputs. Crucially, CO₂ gasification enables catalyst regeneration through the conversion of 90% carbon deposits into reusable media, circumventing energy-intensive combustion processes. This dual-function system couples carbon capture to hydrogen infrastructure, thereby stabilizing production while valorizing waste CO₂. This innovation minimizes reliance on rare metals through efficient regeneration cycles, mitigating resource constraints during energy crises. Full article