Carbon-coated Copper Nanoparticles Research Articles

N-doping carbon-coated Cu@C(N) nanocapsules synthesized by arc plasma toward high-performance ORR electrocatalyst

The development of efficient and cost-effective methods for the synthesis of non-precious metal as the catalytic material for oxygen reduction reaction (ORR) is addressing a key barrier to fuel cell deployment in a wide range of applications. In this study, core-shell carbon-coated copper nanoparticles (Cu@C) were prepared using arc discharge plasma under argon and hydrogen atmospheres. And nitrogen doping was achieved during the subsequent heat treatment using dicyandiamide as the nitrogen source. The results showed that the catalysts had better ORR catalytic activity, better stability and better methanol tolerance than Pt/C, and the ORR reaction process was nearly four-electron pathway. The successful doping of nitrogen increased the reaction sites. And the addition of copper core improved the conductivity of the catalytic material. Meanwhile, the N-C shell layer protected the Cu nanoparticles from dissolving in aqueous solutions or being chemically oxidized, facilitating the electronic interaction of the core Cu nanoparticles with the N-C shell layer. This study provides an insight into the preparation of high-efficiency non-precious metal-based ORR electrocatalysts by DC arc plasma, a beneficial method.

Role of water chemistry on stability, aggregation, and dissolution of uncoated and carbon-coated copper nanoparticles

Intentional or accidental release of copper nanoparticles (Cu-NPs) from consumer products during manufacturing, use, and end-of-life management could pose health and ecological risks. This paper presents a detailed study on the role of water chemistry on the fate of uncoated and carbon-coated Cu-NPs dispersed in aqueous cetyltrimethylammonium bromide (CTAB) surfactant in the presence and absence of humic acids (HAs). A range of water chemistry and HAs had minimum impact on hydrodynamic diameter and zeta-potential values of uncoated and carbon-coated Cu-NPs. The water pH significantly (p < 0.001) affected the aggregation of uncoated Cu-NPs unlike that of carbon-coated Cu-NPs; however, the presence of HAs increased the stability of uncoated Cu-NPs. Although CTAB is considered as an efficient dispersant to stabilize Cu-NPs, the effect descended with time for uncoated Cu-NPs. The dissolution of Cu over time decreased with increasing pH for both uncoated (0.5–50% weight) and carbon-coated (0.5–40% weight) Cu-NPs. However, carbon-coated Cu-NPs exhibited significant dissolution (p < 0.001) at neutral pH than uncoated Cu-NPs may be due to the additional carbon it acquired during coating. Increasing HAs concentration from 0 to 15 mg L−1 at pH 5.5 inhibited aggregations but enhanced dissolution of the uncoated and carbon-coated Cu-NPs. These findings inform risk analysis of Cu-NPs including how Cu-NPs fate, mobility and bioavailability are modulated by particles coating and dispersant, HAs presence, water chemistry and exposure time in dispersion media.

Plasmon-enhanced furfural hydrogenation catalyzed by stable carbon-coated copper nanoparticles driven from metal–organic frameworks

Stable Cu nanoparticles encapsulated by carbon exhibit excellent photocatalytic performance in furfural hydrogenation, due to the enhanced molecular hydrogen dissociation via local surface plasmonic resonance effect under visible light irradiation.

Ferromagnetism and giant paramagnetism of copper nanoparticles in Cum/C nanocomposites

Abstract Carbon coated copper nanoparticles, Cum/C nanocomposites, were synthesized using solid-phase pyrolysis in solid solutions of copper phthalocyanine and metal free copper phthalocyanine, (CuPc)x(H2Pc)1−x where 0 ⩽ x ⩽ 1 . The weight concentration of copper in percentages consistently varies from 0 to 12 wt% and the sizes of copper nanoparticles in samples changes from 2 nm to 500 nm. Samples containing 8 and 12 wt% Cu have a bimodal size distribution. The X-ray diffraction data and HRTEM images show a face-centered cubic structure of Cu nanocrystallites that uniformly distributed in the carbon matrix. The temperature and field dependences of the magnetization in all copper-containing samples exhibit both ferromagnetic and giant-paramagnetic properties in the measured temperature range of 10–300 K. The saturation magnetization of ferromagnetic nanoparticles falls in the range 0.2–1.5 emu/g and weakly depends on the temperature from helium up to the room temperatures. The paramagnetic magnetizations in Cu/C nanocomposites at H = 50 kOe and T = 10 K are practically an order of magnitude higher in all the samples than the ferromagnetic saturation magnetizations. The paramagnetic susceptibilities of the Cum/C nanocomposites at 10 K are of the order of (0.3–1)10−4 emu/gCuOe, which are one and a half to two orders of magnitude higher than the specific paramagnetic susceptibility of the carbon matrix.

The Influence of Ar on the Synthesis of Carbon-coated Copper Nanoparticles in Gaseous Detonation

Background: Carbon-coated metal nanoparticle is a kind of unique nuclear-shell material that is the carbon shell filled with metal particles. It has a great promising future in the application as excellent solid lubricants additives, conducting resin, antiradiation material and so on. As a mature technology, the gas detonation method has been widely used to synthesize various nanomaterials. Method: Using copper acetylacetonate as a precursor to provide carbon and different concentrations of argon as a protective medium for the first time, high quality carbon-coated copper nanoparticles (Cu@C) were synthesized in hydrogen and oxygen. X-ray Diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) were employed to characterize the structure, phase and constituent of the Cu@C nanoparticles to investigate the influence of argon concentration on the synthesis. Results: The XRD pattern, Raman spectroscopy and TEM images confirm the effect of Ar on synthesizing Cu@C, especially on particle size. The minimum average size is around 13 nm, and most of the particle size distribution is in 5-10 nm range. When the argon concentration is high, the detonation process of H2 and O2 will be suppressed, which is not conducive to the graphitization. Conclusion: Argon gas has a catalytic effect on the synthesis of high-quality Cu@C, which could significantly reduce the particle size of detonation products; the grain size appears an obvious downtrend with the concentration of argon increasing, but the high concentration of Ar is disadvantageous for the graphitization of carbon shells.

Carbon-coated copper nanoparticles: Characterization and fabrication via ultrasonic irradiation

Carbon-coated copper nanoparticles can be obtained using sonochemistry and annealing at various temperatures. During annealing under an argon atmosphere, carbonization of organic species forms a carbon layer in the form of a shell, which plays an important role as a reducing agent in the phase transformation of copper oxide to copper. The annealed samples show two main peaks for Raman analysis, centered at 1349 cm−1 (D-band) and 1594 cm−1 (G-band), which are in good agreement with the pattern reported for graphite. The carbon shell was protected from the oxidation and decomposition in air and chemical environment. The shell of carbon-coated copper nanoparticle has pore sizes of 8.8 nm (adsorption) and 5.2 nm (desorption), and a surface area of 159.4 m2 g−1, respectively. Thus, carbon-coated copper nanoparticles, with a high surface area and good electrical conductivity and oxidation resistance in air and chemical solutions owing to the carbon layer, have great potential applications in industrial, environmental, and biological fields.

Carbon-coated copper nanoparticles prepared by detonation method and their thermocatalysis on ammonium perchlorate

Carbon-coated copper nanoparticles (CCNPs) were prepared by initiating a high-density charge pressed with a mixture of microcrystalline wax, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and copper nitrate hydrate (Cu(NO3)2·3H2O) in an explosion vessel filled with nitrogen gas. The detonation products were characterized by transmission electron microcopy (TEM), high resolution transmission electron microcopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Raman spectroscopy. The effects of CCNPs on thermal decomposition of ammonium perchlorate (AP) were also investigated by differential scanning calorimeter (DSC). Results indicated that the detonation products were spherical, 25-40 nm in size, and had an apparent core-shell structure. In this structure, the carbon shell was 3-5 nm thick and mainly composed of graphite, C8 (a kind of carbyne), and amorphous carbon. When 5 wt.% CCNPs was mixed with 95 wt.% AP, the high-temperature decomposition peak of AP decreased by 95.97, 96.99, and 96.69 °Cat heating rates of 5, 10, and 20 °C/min, respectively. Moreover, CCNPs decreased the activation energy of AP as calculated through Kissinger’s method by 25%, which indicated outstanding catalysis for the thermal decomposition of AP.

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Carbon coated copper nanostructures as a green and ligand free nanocatalyst for Suzuki cross-coupling reaction

In this work, carbon coated copper nanoparticles and nanowires were synthesized as a ligand free nanocatalyst that naturally contains ppm levels of Pd with no post-modification via a two-steps reduction-hydrothermal process. Transmittance electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction, inductively coupled plasma optical emission spectrometry (ICP-OES), and Raman spectroscopy were employed for the characterization of the nano-catalyst. The utilization of the synthesized Cu/C nano-catalyst in Suzuki cross coupling reaction showed a high performance in the synthesis of various biaryls in water. Moreover, this catalyst reused successfully with no significant yield decrease even after four subsequently runs.

Photoluminescent colloidal Cu@C-NPs suspensions synthesized by LASL

In this work we report the synthesis of photoluminescent carbon-coated copper nanoparticles (Cu@C-NPs) based colloidal suspensions, using the laser ablation of solids in liquids technique (LASL). LASL experiments were carried out by ablating a Cu solid target immersed in acetone as the liquid medium with ns-laser pulses (1064nm) of a Nd-YAG laser. In all experiments the per pulse laser fluence and the repetition rate frequency were kept constant and the ablation time was varied. The as obtained Cu@C-NPs suspensions were optically characterized with absorption and photoluminescence spectroscopies. Raman spectroscopy was used to give evidence of the carbon shell deposited around the Cu NPs. TEM results showed that 10nm spheroids Cu@C-NPs were obtained. The as obtained Cu@C-NPs suspensions displayed out a PL emission band similar to that for carbon nanoparticles suspensions obtained by the same technique. We have found that the blue-green PL emission band intensity is mainly dependent on the ablation and aging time of the samples. The Cu@C-NPs-based colloidal suspensions can be proposed as multifunctional due to its absorbance and emission properties.

Toxicity of engineered copper (Cu0) nanoparticles to the green alga Chlamydomonas reinhardtii

Environmental context Engineered copper nanoparticles are presently under development for various uses and may thus be finally released into the aquatic environment. Copper is well known to be both an essential and a toxic element for aquatic organisms. Here, we investigate the toxicity of copper nanoparticles to a green alga and compare it with the toxicity of dissolved copper. Abstract The toxicity of carbon-coated copper nanoparticles (CuNPs) to the unicellular green alga Chlamydomonas reinhardtii was investigated and compared with effects of dissolved Cu2+. The CuNPs with an original size of 6–7nm rapidly agglomerated in the medium to average particle sizes of 140–200nm. Dissolved Cu from CuNPs increased over 2h to 1–2% of total Cu. The photosynthetic yield of C. reinhardtii strongly decreased after exposure for 1 or 2h to dissolved CuII in the concentration range 0.1–10μM, whereas this decrease occurred in the total Cu concentration range 1–100μM after exposure to CuNPs. Effects of CuNPs were compared with those of dissolved CuII on the basis of dissolution experiments. CuNP effects on photosynthetic yield were similar or somewhat stronger for the same dissolved Cu2+ concentration. Addition of EDTA as a strong ligand for CuII suppressed the toxicity of dissolved CuII and of CuNPs. These results thus indicate effects on the algae are mostly from free Cu2+.

Preparation of carbon-coated copper nanoparticles by detonation decomposition of copper ion doped sol–gel explosive precursors

Carbon-coated copper (Cu@C) nanoparticles with a core–shell structure were prepared by detonation decomposition of energetic Cu ion doped sol–gel explosive precursors. The composite nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high resolution TEM, energy dispersive X-ray spectroscopy, and Raman spectroscopy, respectively. The results indicate that the as-obtained core–shell structure Cu@C nanoparticles are with diameter about 10–40 nm. The composite nanoparticles are composed of face-centered cubic-Cu and the amorphous/graphitic carbon coating shells. The thermal stability of the obtained samples was studied by a difference scanning calorimetry–thermogravimetric analyzer. By varying the composition of initial mixtures that contain Cu ion explosive precursors, the different size and chemical composition of composite nanoparticles are shown in this study. The growth mechanism of Cu@C was also briefly discussed.

Synthesis and Antioxidant Behavior of Carbon-Coated Copper Nanoparticles

We use plasma method syntheisized Carbon coated copper nanoparticles The structure , size distribution and phase composition of the particles were analysised by TEM , XRD and DSC. Meanwhile, The conductivity of carbon-coated copper nanoparticles were measured. Results show that Carbon coated copper nanoparticles were core-shell structure for the copper core inside, the multi carbon layer outside, around the copper core is graphite-like carbon and far away from the copper core is amorphous carbon. While carbon-coated copper nanoparticles at room temperature and high temperatures have shown good oxidation resistance; The conductivity of carbon-coated copper nanoparticles with metal content increases and when the copper content is 80% the conductivity jump.

Effect of Carbon Coating on the Physico‐chemical Properties and Toxicity of Copper and Nickel Nanoparticles

The primary aim of these interdisciplinary studies is to investigate the effect of surface carbon coating on the physico-chemical properties and toxicity of carbon-coated and noncoated copper and nickel nanoparticles (C-Cu, Cu, C-Ni, Ni NPs) in A549 alveolar epithelial cells. Compared to Cu NPs, C-Cu NPs exhibit protection against surface oxidation, tenfold higher cellular uptake, and fourfold lower release of soluble Cu. The toxicity of C-Cu NPs and Cu NPs is associated with pronounced damage to mitochondrial function and plasma membrane integrity, respectively. Compared to Cu and C-Cu NPs, Ni and C-Ni NPs are less toxic. These studies demonstrate that correlations can be drawn between physico-chemical properties and resultant toxicity of NPs as a function of surface carbon coating.

Antiwear properties of carbon-coated copper nanoparticles used as an additive to a polyalphaolefin

This paper studies the influence of the addition of 25 nm carbon-coated copper nanoparticles on the tribological behavior of a polyalphaolefin (PAO6) and compares this behavior with the case of non-coated copper nanoparticles, determining the influence of coating. A block-on-ring tribometer, a four-ball machine, SEM and EDS were used in this research. The study concludes that the addition of carbon-coated copper nanoparticles decreases wear and increases the load-carrying capacity of PAO6. This tribological improvement is due to the deposition of nanoparticles on the rubbing surfaces and probably by their action as tiny bearings. The carbon-coated copper nanoparticles did not behave better than non-coated ones.

A High-Temperature Reducing Jet Reactor for Flame-Based Metal Nanoparticle Production

We present a new flame-based aerosol reactor configuration that combines thermal decomposition and hydrogen reduction to produce metal nanoparticles. This approach uses a fuel-rich hydrogen flame as a source of low-cost energy to initiate particle synthesis, but separates the flame chemistry from the particle formation chemistry. Hot combustion products pass through a nozzle to produce a high-temperature reducing jet. A liquid precursor solution is rapidly atomized, evaporated, and decomposed by the expanding jet, initiating particle formation. In particular, here we have produced carbon-coated copper nanoparticles from an aqueous copper formate precursor solution and characterized them by aerosol mobility distribution measurements, electron microscopy, and x-ray diffraction. Copper serves here as a prototype for non-oxide materials that are generally difficult to produce in flame-based reactors. This work demonstrates that such materials can be produced in substantial quantities with particle diameters b...

Nanoparticle cytotoxicity depends on intracellular solubility: Comparison of stabilized copper metal and degradable copper oxide nanoparticles

Metal nanoparticles have distinctly different chemical and physical properties than currently investigated oxides. Since pure metallic nanoparticles are igniting at air, carbon stabilized copper nanoparticles were used as representative material for this class. Using copper as a representative example, we compare the cytotoxicity of copper metal nanoparticles stabilized by a carbon layer to copper oxide nanoparticles using two different cell lines. Keeping the copper exposure dose constant, the two forms of copper showed a distinctly different response. Whilst copper oxide had already been reported to be highly cytotoxic, carbon-coated copper nanoparticles were much less cytotoxic and more tolerated. Measuring the two material's intra- and extracellular solubility in model buffers explained this difference on the basis of altered copper release when supplying copper metal or the corresponding oxide particles to the cells. Control experiments using pure carbon nanoparticles were used to exclude significant surface effects. Reference experiments with ionic copper solutions confirmed a similar response of cultures if exposed to copper oxide nanoparticles or ionic copper. These observations are in line with a Trojan horse-type mechanism and illustrate the dominating influence of physico-chemical parameters on the cytotoxicity of a given metal.

Carbon-coated copper nanoparticles: synthesis, characterization and optical properties

Download options Please wait... Supplementary files TEM images of the products synthesized with different amountsof glucose PDF (1327K) Article information DOI https://doi.org/10.1039/B906796E Article type Letter Submitted 03 Apr 2009 Accepted 28 May 2009 First published 05 Jun 2009 Download Citation New J. Chem., 2009,33, 1474-1477 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Carbon-coated copper nanoparticles: synthesis, characterization and optical properties J. Li and C. Liu, New J. Chem., 2009, 33, 1474 DOI: 10.1039/B906796E To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Jing Li Chun-yan Liu

Insulator coated metal nanoparticles with a core/shell geometry exhibit a temperature sensitivity similar to advanced spinels

The preparation of carbon-coated copper nanoparticles with different carbon layers resulted in materials with a highly sensitive pressure and temperature dependent conductivity. The core/shell geometry of these carbon/metal composites afforded two distinctly different electrical behaviors depending on the carbon layer properties. Graphene layers with a predominant sp 2 character showed an ill-defined bandgap structure as evidenced by UV–vis diffuse reflectance spectroscopy. The resulting composites were weak conductors with low sensitivity. Use of predominately insulating carbon layers with a well-defined bandgap of above 1.9 eV resulted in composites with a material constant β of over 4700 K which is comparable to currently used commercial spinels. A theoretical analysis and detailed material characterization by Raman spectroscopy, X-ray diffraction, 13C NMR spectroscopy and thermoanalysis suggested a tunneling based conduction mechanism in these core/shell materials. This interpretation was supported by a good correlation between experimental data and the estimated effects arising from the theoretical analysis of the tunneling effects.

Carbon-Coated Core Shell Structured Copper and Nickel Nanoparticles Synthesized in an Ionic Liquid

A simple synthetic route to prepare carbon-coated copper or nickel nanoparticles is developed in an ionic liquid under microwave heating. The obtained products are characterized by XRD, UV-spectroscopy, and Raman spectroscopy. The morphologies are studied with the help of TEM, HRSEM, and HRTEM. A bulk transport property for carbon coated nickel is reported in this letter.