Search Results (20)

This paper presents a non-enzymatic sensor for glucose detection in an environment where glucose and insulin coexist. The sensor is based on a three-electrode chip fabricated by etching the copper foil of a printed circuit board. The working electrode is coated with a graphene oxide-polyvinyl alcohol composite film, followed by the electroplating of a nickel–cobalt layer and an additional surface treatment using O₂ plasma. The experimental results indicate that within a glucose concentration of 2 mM to 10 mM and an insulin concentration of 0.1 mM to 1 mM, the measured current exhibits a linear relationship with the concentration of glucose or insulin, regardless of whether cyclic voltammetry or linear sweep voltammetry is used. However, the detection limit for insulin is 0.01 mM, ensuring that glucose detection remains unaffected by insulin interference. In this sensor, nickel–cobalt serves as a catalyst for glucose and insulin detection, while the graphene oxide-polyvinyl alcohol composite enhances sensing performance. Full article

Copper foil has been widely adopted as the anode current collector in commercial lithium-ion batteries (LIBs) due to its exceptional electrical conductivity, mechanical flexibility, and low cost. However, the smooth surface of copper foil often leads to active material delamination during cycling, resulting in accelerated capacity degradation. To address this limitation, this study developed a novel composite current collector featuring a high specific surface area and rough porous architecture through a dip-coating method. The fabrication process employs copper mesh as a structural skeleton, integrated with carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) as functional fillers. Compared to conventional metallic copper foils, the composite current collector demonstrates superior interfacial wettability, enhanced adhesion strength, and reduced contact resistance. When paired with graphite as the active material, the graphite composite electrode exhibits outstanding cycling stability and rate capability. Specifically, the graphite composite electrode delivers a specific capacity of 297.9 mAh g⁻¹ with 94.3% capacity retention after 200 cycles at 0.5 C, significantly outperforming the graphite–copper foil counterpart (238.3 mAh g⁻¹, 81.2% retention). This work provides an innovative strategy for enhancing battery performance through the rational design of efficient and durable current collectors. Full article

Nano-transfer printing (nTP) has emerged as an effective method for fabricating three-dimensional (3D) nanopatterns on both flat and non-planar substrates. However, most transfer-printed 3D patterns tend to exhibit non-discrete and/or non-porous structures, limiting their application in high-precision nanofabrication. In this study, we introduce a simple and versatile approach to produce highly ordered, porous 3D cross-bar arrays through precise control of the nTP process parameters. By selectively adjusting the polymer solution concentration and spin-coating conditions, we successfully generated discrete, periodic line patterns, which were then stacked at a 90-degree angle to form a porous 3D cross-bar structure. This technique enabled the direct transfer printing of PMMA line patterns with well-defined, square-arrayed holes, without requiring additional deposition of functional materials. This method was applied across diverse substrates, including planar Si wafers, flexible PET, metallic copper foil, and transparent glass, demonstrating its adaptability. These well-defined 3D cross-bar patterns enhance the versatility of nTP and are anticipated to find broad applicability in various nano-to-microscale electronic devices, offering high surface area and structural precision to support enhanced functionality and performance. Full article

Silicon (Si) as the anode material for lithium-ion batteries (LIBs) has attracted much attention due to its high theoretical specific capacity (4200 mAh/g). However, the specific capacity and cycle stability of the LIBs are reduced due to the pulverization caused by the expansion of Si coated on Cu (copper) foil during cycles. In order to solve this problem, researchers have used an ultra-thin Si deposition layer as the electrode, which improves cyclic stability and obtains high initial coulomb efficiency of LIBs. However, suitable substrate selection is crucial to fabricate an ultrathin Si deposition layer electrode with excellent performance, and a substrate with a three-dimensional porous structure is desirable to ensure the deposition of an ultrathin Si layer on the whole surface of the substrate. In this paper, the Si thin layer has been deposited on a binder-free hybrid film of carbon nanotubes (CNTs) and carbon nanocoils (CNCs) by magnetron sputtering. Compared with densely packed CNT film and flat Cu foil, the loose and porous film provides a large surface area and space for Si deposition, and Si can be deposited not only on the surface but also in the interior part of the film. The film provides a large number of channels for the diffusion and transmission of Li⁺, resulting in the rapid diffusion rate of Li⁺, which improves the effective lithium storage utilization of Si. Furthermore, the CNC itself is super elastic, and film provides an elastic skeleton for the Si deposition layer, which eases its volume expansion during charge and discharge processes. Electrochemical tests have showed that the Si/CNT–CNC film electrode has excellent performance as anode for LIBs. After 200 cycles, the Si/CNT–CNC film electrode still had possessed a specific capacity of 2500 mAh/g, a capacity retention of 92.8% and a coulomb efficiency of 99%. This paper provides an effective way to fabricate high performance Si-nanocarbon composite electrodes for LIBs. Full article

Bacterial adhesion and biofilm maturation is significantly influenced by surface properties, encompassing both bare surfaces and single or multi-layered coatings. Hence, there is an utmost interest in exploring the intricacies of gene regulation in sulfate-reducing bacteria (SRB) on copper and graphene-coated copper surfaces. In this study, Oleidesulfovibrio alaskensis G20 was used as the model SRB to elucidate the pathways that govern pivotal roles during biofilm formation on the graphene layers. Employing a potent reporter green fluorescent protein (GFP) tagged to O. alaskensis G20, the spatial structure of O. alaskensis G20 biofilm on copper foil (CuF), single-layer graphene-coated copper (Cu-GrI), and double-layer graphene-coated copper (Cu-GrII) surfaces was investigated. Biofilm formation on CuF, Cu-GrI, and Cu-GrII surfaces was quantified using CLSM z-stack images within COMSTAT v2 software. The results revealed that CuF, Cu-GrI, and Cu-GrII did not affect the formation of the GFP-tagged O. alaskensis G20 biofilm architecture. qPCR expression showed insignificant fold changes for outer membrane components regulating the quorum-sensing system, and global regulatory proteins between the uncoated and coated surfaces. Notably, a significant expression was observed within the sulfate reduction pathway confined to dissimilatory sulfite reductases on the Cu-GrII surface compared to the CuF and Cu-GrI surfaces. Full article

One of the greatest challenges worldwide is containing the spread of problematic microorganisms. A promising approach is the use of antimicrobial coatings (AMCs). The antimicrobial potential of certain metals, including copper and zinc, has already been verified. In this study, polyethylene terephthalate and aluminum (PET-Al) foils were coated with copper, zinc, and a combination of these two metals, known as core–shell particles, respectively. The resistance of the three different types of coatings to mechanical and chemical exposure was evaluated in various ways. Further, the bacteria Staphylococcus aureus and the bacteriophage ϕ6 were used to assess the antimicrobial efficacy of the coatings. The best efficacy was achieved with the pure copper coating, which was not convincing in the abrasion tests. The result was a considerable loss of copper particles on the surfaces and reduced effectiveness against the microorganisms. The core–shell particles demonstrated better adhesion to the surfaces after abrasion tests and against most chemical agents. In addition, the antimicrobial efficiency remained more stable after the washability treatment. Thus, the core–shell particles had several benefits over the pure copper and zinc coatings. In addition, the best core–shell loading for durability and efficacy was determined in this study. Full article

Ti/IrO₂-Ta₂O₅ electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we have developed a composite anode of Ti/Ta-Ti/IrO₂-Ta₂O₅ with a Ta-Ti alloy interlayer deposited on a Ti substrate by double-glow plasma surface alloying, and the IrO₂-Ta₂O₅ surface coating prepared by the traditional thermal decomposition method. This investigation indicates that the electrode with Ta-Ti alloy interlayer reduces the agglomerates of precipitated IrO₂ nanoparticles and refines the grain size of IrO₂, thereby increasing the number of active sites and enhancing the electrocatalytic activity. Accelerated lifetime tests demonstrate that the Ti/Ta-Ti/IrO₂-Ta₂O₅ electrode exhibits a much higher stability than the Ti/IrO₂-Ta₂O₅ electrode. The significant improvement in electrochemical stability is attributed to the Ta-Ti interlayer, which offers high corrosion resistance and effective protection for the titanium substrate. Full article

Due to the direct contact between the probe and sample, the contact of the four-probe method is important for the structural integrity of the sample and the accuracy of electrical resistivity measurements, especially for surface-coated metal foils with multilayered structures. Here, we analyzed the accuracy and stability of four-probe method probing on different sides of copper (Cu) foils covered with graphene (Gr). Theoretical simulations showed similar potential distributions on the probe tip when probing on the Cu and Gr sides. The resistivity of the Gr/Cu foil was 2.31 ± 0.02 μΩ·cm when measured by probing on the Cu side, and 2.30 ± 0.10 μΩ·cm when measured by probing on the Gr side. The major difference in the mean deviation is attributed to surface damage. In addition, the method of probing on the Cu side was sensitive to the resistivity changes of Gr induced by polymers with a dielectric constant range of 2~12, which is consistent with the calculations based on the random phase approximation theory. Our results demonstrated that the probing position on the metal side in the four-probe method can effectively protect the structural integrity of the functional surface-coated layer and maintain the high sensitivity of the measurement, providing guidance for the resistivity measurements of other similarly heterogeneous materials. Full article

In this study, an electrode slurry composed of molybdenum disulfide (MoS₂) and vapor-grown carbon fiber (VGCF) prepared through a solid-phase synthesis method was blade-coated onto copper foil to form a thick film as the anode for lithium-ion batteries. In previously reported work, MoS₂-based lithium-ion batteries have experienced gradual deformation, fracture, and pulverization of electrode materials during the charge and discharge cycling process. This leads to an unstable electrode structure and rapid decline in battery capacity. Furthermore, MoS₂ nanosheets tend to aggregate over charge and discharge cycles, which diminishes the surface activity of the material and results in poor electrochemical performance. In this study, we altered the density of the MoS₂–carbon fiber/Cu foil anode electrode by rolling. Three different densities of electrode sheets were obtained through varying rolling repetitions. Our study shows the best electrochemical performance was achieved at a material density of 2.2 g/cm³, maintaining a capacity of 427 mAh/g even after 80 cycles. Full article

The production of hydrogen using electrolysis contributes to the development of more important renewable energy sources. Nowadays, the synthesis of alloys, which can be successfully applied as catalysts instead of precious metals, is carefully investigated. One-step electrodeposition is a surface engineering method that allows for the control of the morphology of the deposit by changing deposition parameters. It is a simple and low-cost process based on electrochemical synthesis from electrolytes, usually non-toxic crystal modifiers. In this work, a conical Ni structure on Cu foil was produced using this technique. The effect of the copper substrate on the morphology of the developed nanocones was analyzed using a Scanning Electron Microscope (SEM). Then, the catalytic performance of the synthesized coatings was carefully analyzed based on the results of a linear sweep voltammetry experiment and the measurements of their wettability and electrochemical active surface area. The proposed method of Cu treatment, including polishing with sandpapers, influenced the growth of cones and, consequently, increased the catalytic activity and active surface area of the Ni coatings in comparison to the bulk Ni sample. Full article

Due to the COVID-19 pandemic, researchers have focused on new preventive measures to limit the spread of SARS-CoV-2. One promising application is the usage of antimicrobial materials on often-touched surfaces to reduce the load of infectious virus particles. Since tests with in vitro-propagated SARS-CoV-2 require biosafety level 3 (BSL-3) laboratories with limited capacities and high costs, experiments with an appropriate surrogate like the bacteriophage ɸ6 are preferred in most studies. The aim of this study was to compare ɸ6 and SARS-CoV-2 within antiviral surface tests. Different concentrations of copper coatings on polyethylene terephthalate (PET) were used to determine their neutralizing activity against ɸ6 and SARS-CoV-2. The incubation on the different specimens led to similar inactivation of both SARS-CoV-2 and ɸ6. After 24 h, no infectious virus particles were evident on any of the tested samples. Shorter incubation periods on specimens with high copper concentrations also showed a complete inactivation. In contrast, the uncoated PET foils resulted only in a negligible reduced inactivation during the one-hour incubation. The similar reduction rate for ɸ6 and SARS-CoV-2 in our experiments provide further evidence that the bacteriophage ɸ6 is an adequate model organism for SARS-CoV-2 for this type of testing. Full article

Engineering the surface orientation of face-centered cubic (fcc) metals to the close-packed {111} plane can significantly enhance their oxidation resistance. However, owing to the synergetic effect of surface energy density ($\dot{\gamma }$) and strain energy density ($\omega$), such close-packed surface orientation can currently only be achieved by atomic-level thin film epitaxy or monocrystallization of polycrystalline metals. In this study, we characterized the microstructures of pure copper (Cu) foil and two types of graphene-coated Cu (Gr/Cu) foils and observed a 12~14 nm thick reconstructed surface layer with the {111} orientation in the high-temperature deposited Gr/{001} Cu surface. Combining the statistical results with thermodynamic analysis, we proposed a surface melting-solidification mechanism for the reconstruction of the Cu surface from {001} orientation to {111} orientation. This process is dominated by Gr/Cu interfacial energy and is particularly promoted by high-temperature surface melting. We also validated such a mechanism by examining Cu surfaces coated by h-BN (hexagonal boron nitride) and amorphous carbon. Our findings suggest a possible strategy to enhance the surface properties of fcc metals via engineering surface crystallography. Full article

For some challenging applications of the high-performance thermoplastic polyetheretherketone (PEEK) in engineering or medical fields, the bonding to other materials is important. In these cases, modifications of the inert polymer surface are often necessary. Results from the literature with respect to sandblasting, corona discharge, plasma treatment, excimer-laser irradiation, and chromium-sulfuric-acid etching are described and discussed. Our own detailed studies of these methods under well-defined experimental conditions are reported, which make their comparability possible and support the assessment for certain applications. PEEK films coated with copper are of special interest due to their potential for flexible electronics. Copper foils glued by an epoxy resin and copper layers from physical vapor deposition are compared with respect to their mechanical adhesion. Surface properties were characterized with respect to roughness, contact angle, and oxygen-to-carbon (O/C) ratio. The latter has been found to be the most decisive parameter for good adhesion. It was shown that an enhancement of the O/C ratio can be achieved in several ways. The advantages and disadvantages of the methods applied are discussed under various aspects of applications. Full article

The development of mixed oxide electrodes is being intensively investigated to reduce the high cost associated with the use of noble metals and to obtain versatile and long-lasting devices. To evaluate their use for charge storage or anodic oxidation, in this paper, thin-film electrodes coated with ruthenium (RuO_x) and copper oxide (CuO_x) are fabricated by thermal decomposition of organic solutions containing the precursors by drop-casting on titanium (Ti) foils. The coating consisted of four layers of metal oxide. To investigate the effect of copper (Cu) on electrochemical performances, different approaches are adopted by varying the ratios of precursors’ concentration and including a RuO_x interlayer. A comparison with samples obtained by only RuO_x has been also performed. The electrodes are characterized using scanning electron microscopy (SEM), cyclic (CV) and linear sweep (LSV) voltammetry, electrochemical impedance spectroscopy (EIS), and corrosion tests. The addition of Cu enhances the capacitive response of the materials and promotes electron transfer reversibility. The coatings obtained by the highest Ru:Cu ratio (95:5) exhibit a more uniform surface distribution and increased corrosion resistance. The interlayer is beneficial to further reduce the corrosion susceptibility and to promote the oxygen evolution but detrimental in the charge storage power. The results suggest the possibility to enhance the electrochemical performance of expensive RuO_x through a combination with a low amount of cheaper and more abundant CuO_x. Full article

In this study, hydrogen (H₂) and methane (CH₄) were used as reactive gases, and chemical vapor deposition (CVD) was used to grow single-layer graphene on a copper foil substrate. The single-layer graphene obtained was transferred to a single-crystal silicon substrate by PMMA transfer technology for the subsequent growth of nano zinc oxide. The characteristics of CVD-deposited graphene were analyzed by a Raman spectrometer, an optical microscope, a four-point probe, and an ultraviolet/visible spectrometer. The sol–gel method was applied to prepare the zinc oxide seed layer film with the spin-coating method, with methanol, zinc acetate, and sodium hydroxide as the precursors for growing ZnO nanostructures. On top of the ZnO seed layer, a one-dimensional zinc oxide nanostructure was grown by a hydrothermal method at 95 °C, using a zinc nitrate and hexamethylenetetramine mixture solution. The characteristics of the nano zinc oxide were analyzed by scanning electron microscope(SEM),x-ray diffractometer(XRD), and Raman spectrometer. The obtained graphene/zinc oxide nano-heterostructure sensor has a sensitivity of 1.06 at a sensing temperature of 205 °C and a concentration of hydrogen as low as 5 ppm, with excellent sensing repeatability. The main reason for this is that the zinc oxide nanostructure has a large specific surface area, and many oxygen vacancy defects exist on its surface. In addition, the P–N heterojunction formed between the n-type zinc oxide and the p-type graphene also contributes to hydrogen sensing. Full article