Harvesting energy from the mechanical motion has been demonstrated to be a preferable strategy to satisfy the requirements for self-powered electronics. Here we report a flexible and stable induction ...electrode based on graphene/Cu heterostructure, which is fabricated by electrodeposition and spin-coating, and is also utilized in energy harvesting for triboelectric nanogenerator (TENG). Typically, graphene dispersion prepared by physical exfoliation is spin-coated on the copper nanostructure based on PDMS. Besides, we provide favorable evidences that electrons transfer from graphene to copper, and ignite the reduced reaction of copper oxides. The function of graphene in avoiding the oxidation of copper nanostructure, thus improving the stability of graphene/Cu heterostructure and achieving its applications in triboelectric nanogenerator, is confirmed. The interactive mechanism is formulated, including energy barrier, metal work function and the electrochemical potential difference between graphene, copper and oxygen. The enhanced stability of graphene/Cu heterostructure is inspected by the chemical state of copper as the function of exposure time, and the applicability is also evaluated by their output electrical performance for TENG applications.
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•Electrodeposition is proved to be feasible for fabricating flexible electrode in TENG.•Electron transfer mechanism of graphene/Cu heterostructure is proposed and verified.•Skin-based flexible S-TENG is utilized for energy harvesting.
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•Hydrogen evolution assisted (HEA) electroplating was applied for copper growth.•Cyclic electroplating method was used to control the copper nanostructure.•Scan rate of 100 mV/s has ...been identified for fast growth of copper.
Recent progress in hydrogen evolution assisted (HEA) electroplating has shown promises for fast lateral growth of copper on various rigid and flexible substrates. In this method, concurrent to the copper reduction, hydrogen bubbles are generated at the cathode resulting in a porous copper layer with a growth rate a few orders of magnitude faster than the standard electroplating method. However, the application of constant voltage does not allow bubbles to leave the surface resulting in non-uniform copper growth and unpredictable nanostructures. To allow the hydrogen bubbles to leave the surface, we have applied a cyclic electroplating method in a voltage range that the electroplating alternates between the HEA and non-HEA modes. The effect of the voltage range and the voltage scan rate on the lateral growth of copper and the quality of the copper layer were investigated on a patterned copper track on a standard printed circuit board (PCB). The fastest growth rate of 55 µm/s was obtained for a voltage range between −1.5 V and −0.8 V with a scan rate of 100 mV/s. The scanning electron microscopy (SEM) images of different samples revealed that the scan rate affects the nanostructure of the grown copper layer. The feasibility of applying the HEA cyclic electroplating method for developing wearable electronics was demonstrated by growing copper on a piece of fabric to make contact with the pins of a light emitting diode.
Sepsis, an infectious disease affecting millions of people’s health worldwide each year, calls for urgent attention to an improvement of analytical devices. Chemiluminescence immunoassay is a typical ...diagnostic method utilized to assess the risk development of sepsis. However, due to its high-cost, delayed, and complicated procedure, the practical utilization is therefore undoubtedly limited, especially for point-of-care test. Herein, we fabricated for the first time an immunosensor based on dendritic copper nanostructures (CuNSs) combined with 4-aminobenzoic acid (4-AB, the diazonium salt) as antibody linker modified on a screen-printed graphene electrode for the early detection of the sepsis biomarker interleukin-6 (IL-6). The electrode fabrication is made by electrodeposition, thus eliminating the multistep of nanomaterial synthesis and time wasting. The resulting dendritic CuNSs significantly increase the effective surface area (1.2 times) and the sensor’s performance. The morphology of this combination was characterized using CV, EIS, SEM, EDX, and FTIR techniques. In the detection process, the appearance of IL-6 suppresses the current response of the redox probe indicator measured by differential pulse voltammetry due to the antibody-antigen complex. The subtraction of signal (Δ
I
) was interpreted as IL-6 concentration. This sensor exhibited a linear range from 0.05 to 500 pg mL
−1
with low detection limit of 0.02 pg mL
−1
, proving a possibility for early sepsis screening. In addition, the established immunosensor can successfully quantify IL-6 in human serum sample, in which the results agreed well with those achieved using the standard approach, further showing high practical applicability of this developed immunosensor.
Graphical abstract
Highlights
Immunosensor based on CuNSs combined with 4-AB for IL-6 was first demonstrated.
Composite of CuNSs and 4-AB significantly enhanced the sensor’s performance.
Extremely high sensitivity with excellent selectivity was achieved.
The sensor fabricated by electrodeposition can eliminate the multistep of preparation.
This sensor was reliable and triumphantly applied to quantify IL-6 in human serum.
The formation of porous material structures has been widely investigated for the development of high-performance energy materials, catalysts, and chemical sensing devices. Various nanoporous ...structure fabrication methods are based on wet-chemical processes, which require precise control of the process parameters. Physical vapor deposition such as thermal evaporation utilizes high vacuum so that the deposition process is relatively simple, free of contamination, and easily reproduced. However, because of the long mean-free-path of the evaporated atoms in high vacuum, heterogeneous nucleation and the growth of adatoms occurs on the substrate surface, which results in the formation of dense and compact thin films. But by changing the working pressure, various morphologies of porous nanostructures can be obtained. As applied to copper, with increasing pressure the thin film evolves from a dense structure to a coral-like nanoporous structure through a porous columnar structure. All of the porous structures consist of nanoparticle aggregates, where copper nanoparticles are connected to each other, and many nano-gaps are found inside the aggregates. A surface plasmonic effect is expected. The porous copper nanostructured films demonstrated high surfaceenhanced Raman spectroscopy activity.
(Received December 16, 2020; Accepted December 31, 2020)
Water splitting is an essential process for converting light energy into easily storable energy in the form of hydrogen. As environmentally preferable catalysts, Cu‐based materials have attracted ...attention as water‐splitting catalysts. To enhance the efficiency of water splitting, a reaction process should be developed. Single‐molecule junctions (SMJs) are attractive structures for developing these reactions because the molecule electronic state is significantly modulated, and characteristic electromagnetic effects can be expected. Here, water splitting is induced at Cu‐based SMJ and the produced hydrogen is characterized at a single‐molecule scale by employing electron transport measurements. After visible light irradiation, the conductance states originate from Cu/hydrogen molecule/Cu junctions, while before irradiation, only Cu/water molecule/Cu junctions were observed. The vibration spectra obtained from inelastic electron tunneling spectroscopy combined with the first‐principles calculations reveal that the water molecule trapped between the Cu electrodes is decomposed and that hydrogen is produced. Time‐dependent and wavelength‐dependent measurements show that localized‐surface plasmon decomposes the water molecule in the vicinity of the junction. These findings indicate the potential ability of Cu‐based materials for photocatalysis.
Water splitting is achieved via visible‐light irradiation on a copper‐based single‐molecule junction, which allowed the detection of chemical reactants at the smallest scale possible. The electric current measurements and inelastic electron tunneling spectroscopy distinguish the produced hydrogen from the water molecule and characterized the junction structure with the support of the first‐principles transport calculations based on the density functional theory.
This study reports the unprecedented, novel and eco-friendly method for the synthesis of three-dimensional (3D) copper nanostructure having flower like morphology using leaf extract of Ficus ...benghalensis. The catalytic activity of copper nanoflowers (CuNFs) was investigated against methylene blue (MB) used as a modal dye pollutant. Scanning electron micrograph evidently designated 3D appearance of nanoflowers within a size range from 250 nm to 2.5 μm. Energy-dispersive X-ray spectra showed the presence of copper elements in the nanoflowers. Fourier-transform infrared spectra clearly demonstrated the presence of biomolecules which is responsible for the synthesis of CuNFs. The catalytic activity of the synthesised CuNFs was monitored by ultraviolet–visible spectroscopy. The MB was degraded by 72% in 85 min on addition of CuNFs and the rate constant (k) was found to be 0.77 × 10−3 s−1. This method adapted for synthesis of CuNFs offers a valuable contribution in the area of nanomaterial synthesis and in water research by suggesting a sustainable and an alternative route for removal of toxic solvents and waste materials.
The process of copper nanostructure formation on a silicon dioxide substrate was simulated using the molecular dynamics method. The process parameters corresponded to the conditions in a low-pressure ...gas-discharge plasma. The relationship between the nanostructure formation rate and the main plasma parameters was determined.
The formation of porous material structures has been widely investigated for the development of high-performance energy materials, catalysts, and chemical sensing devices. Various nanoporous ...structure fabrication methods are based on wet-chemical processes, which require precise control of the process parameters. Physical vapor deposition such as thermal evaporation utilizes high vacuum so that the deposition process is relatively simple, free of contamination, and easily reproduced. However, because of the long mean-free-path of the evaporated atoms in high vacuum, heterogeneous nucleation and the growth of adatoms occurs on the substrate surface, which results in the formation of dense and compact thin films. But by changing the working pressure, various morphologies of porous nanostructures can be obtained. As applied to copper, with increasing pressure the thin film evolves from a dense structure to a coral-like nanoporous structure through a porous columnar structure. All of the porous structures consist of nanoparticle aggregates, where copper nanoparticles are connected to each other, and many nano-gaps are found inside the aggregates. A surface plasmonic effect is expected. The porous copper nanostructured films demonstrated high surfaceenhanced Raman spectroscopy activity.
Shale-like copper nanostructure was synthesized for the first time from a
water-in-oil microemulsion medium comprising Triton? X-100/cyclohexane/water
ternary system. The nanoshales were synthesized ...through chemical reduction
by hydrazinium hydroxide in alkaline medium. The nanoshales were
characterized by scanning electron microscopy (SEM) and X-ray diffraction
(XRD) patterns.
nema
In this study, Copper (Cu) nanostructures (CuNS) were electrochemically deposited on a film of multiwall carbon nanotubes (MWCNTs) modified pencil graphite electrode (MWCNTs/PGE) by cyclic ...voltammetry method to fabricate a CuNS–MWCNTs composite sensor (CuNS–MWCNT/PGE) for hydrazine detection. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) were used for the characterization of CuNS on the MWCNTs matrix. The composite of CuNS-MWCNTs was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The preliminary studies showed that the proposed sensor have a synergistic electrocatalytic activity for the oxidation of hydrazine in phosphate buffer. The catalytic currents of square wave voltammetry had a linear correlation with the hydrazine concentration in the range of 0.1 to 800μM with a low detection limit of 70nM. Moreover, the amperometric oxidation current exhibited a linear correlation with hydrazine concentration in the concentration range of 50–800μM with the detection limit of 4.3μM. The proposed electrode was used for the determination of hydrazine in real samples and the results were promising. Empirical results also indicated that the sensor had good reproducibility, long-term stability, and the response of the sensor to hydrazine was free from interferences. Moreover, the proposed sensor benefits from simple preparation, low cost, outstanding sensitivity, selectivity, and reproducibility for hydrazine determination.
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•The Copper nanostructures (CuNS) were prepared by cyclic voltammetry deposition.•The CuNS-MWCNT/PGE sensor shows high activity toward hydrazine (N2H4).•The proposed sensor exhibits a wide linear range (0.1 to 800μM), low detection limit (70nM), high sensitivity and stability for hydrazine.
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