Distribution Of Cu Nanoparticles Research Articles

Dimensionally integrated nanoarchitectonics with Cu nanoparticles embedded in g-C3N4 nanosheets for efficient photocatalytic hydrogen generation and dye degradation

High-efficiency and sustainable non-noble metal cocatalyst can reduce the reaction barrier of photocatalysis or electrocatalysis to promote the hydrogen evolution reaction, which provides a feasible method for large-scale hydrogen production. A one-step thermal polymerization method was developed to successfully incorporate copper (Cu) into graphite nitride carbon (g-C3N4) through a mechanochemical pre-treatment and subsequently thermal polymerization. The synthesis controlling is a key to arrange the distribution of Cu nanoparticles in g-C3N4 nanosheets. Photocatalytic hydrogen generation tests were carried out for Cu incorporated g-C3N4 nanosheets obtained at different temperatures. Cu incorporated g-C3N4 at 680 °C (CCN-680) revealed the best H2 generation rate of 2985 μmol g-1 h−1, which was 12.7 times of that of pure g-C3N4 nanosheets obtained at same temperature. Furthermore, the degradation of methylene blue (MB) indicated that sample CCN-680-3 with optimized Cu ratio revealed enhanced performance, in which the degradation rate of MB increased from 80 to 97 % within 60 min. The introduction of Cu narrowed the band gap of g-C3N4 nanosheets, expanded light response in visible region, and finally improved greatly the separation efficiency of photogenerated charge carriers. These results are significant for highly efficient and stable photocatalysts.

3D Carbon Fiber Skeleton Film Modified with Gradient Cu Nanoparticles as Auxiliary Anode Regulates Dendrite-Free, Bottom-Up Zinc Deposition.

Achieving stable Zn plating/stripping under high current density and large area capacity remains a major challenge for metal Zn anodes. To address this issue, common filter paper is utilized to construct 3D carbon fiber skeleton film modified with gradient Cu nanoparticles (CFF@Cu). The original zincophobic hydrophilic CFF is transformed into gradient zincophilic and reversed gradient hydrophilic composite, due to the gradient distribution of Cu nanoparticles. When CFF@Cu is placed above Zn foil as an auxiliary anode, Zn foil anode exhibits stable, reversible, and dendrite-free Zn plating/stripping for 1200h at 10mA cm-2 and 2 mAh cm-2, 2000h at 2mA cm-2 and 2 mAh cm-2, 340h at 10mA cm-2 and 10 mAh cm-2. Additionally, nucleation barrier of Zn, Zn2+ transport and deposition kinetics are improved. The deposits on the Zn foil anode become homogeneous, dense, and fine. Side reactions and by-products are effectively inhibited. The excellent performance is mainly attributed to the gradient zincophilic field in 3D CFF. A portion of Zn2+ is captured by Cu and deposited within CFF@Cu from bottom to top, which reduces and homogenizes Zn2+ flux on Zn foil, as well as weakens and homogenizes electric field on Zn foil.

Z-scheme WOx/Cu-g-C3N4 heterojunction nanoarchitectonics with promoted charge separation and transfer towards efficient full solar-spectrum photocatalysis

Construction of Z-scheme heterojunctions has been considered one superb method in promoting solar-assisted charge carrier separation of carbon-based materials to achieve efficient utilization of solar energy in hydrogen production and CO2 reduction. One interesting concept in nanofabrication that has become trend recent years is nanoarchitectonics. A heterostructure photocatalyst constructed based on the idea of nanoarchitectonics using the combination of g-C3N4, metal and an additional semiconducting nanocomposite is investigated in this paper. Z-scheme tungsten oxide incorporated copper modified graphitic carbon nitride (WOx/Cu-g-C3N4) heterostructures are fabricated via immobilization of WOx on Cu nanoparticles modified superior thin g-C3N4 nanosheets. Mechano-chemical pre-reaction and a two-step high-temperature thermal polymerization process are the keys in attaining homogeneous distribution of Cu nanoparticles in g-C3N4 nanosheets. The horizontal growth of homogeneously distributed WOx nanobelts on Cu modified g-C3N4 (Cu-g-C3N4) base via solvothermal synthesis is achieved. The photocatalytic performances of the heterostructures are evaluated through water splitting and CO2 photoreduction measurements in full solar spectrum irradiation condition. The presence of Cu nanoparticles in the composite system improves charge transport between g-C3N4 and WOx and thus enhances the photocatalytic performances (H2 generation and CO2 photoreduction) of the composite material, while the presence of WOx nanocomposites enhances light absorption of the composite material in the near infrared range. The synthesized heterostructure with optimized WOx to Cu-g-C3N4 ratio and in case of no co-catalyst addition exhibits enhanced photocatalytic H2 evolution (4560 μmolg-1h−1) as well as excellent CO2 reduction rate (5.89 μmolg-1h−1 for CO generation).

Copper Doped PPy/MWCNT Nanocomposite Materials for Supercapacitor Applications

We report the structural, morphological, and electrochemical properties of polypyrrole (PPy), copper doped PPy (Cu/PPy), and copper doped polypyrrole multi-walled carbon nanotubes (Cu/PPy/MWCTs) prepared by oxidative polymerization technique. The incorporation of Cu in the form of nanoparticles in the composites was confirmed from XRD data. The granular morphology of PPy was observed from the FESEM micrograph. However, the size of the grains was decreased with Cu nanoparticle insertion in the matrix. The uniform distribution of Cu nanoparticles in the Cu/PPy and Cu/PPy/MWCTs nanocomposites has been evidenced from TEM images. The highest specific capacitance of 311 F/g at a scan rate of 10 mV/s is achieved in the case of Cu/PPy/MWCTs composite. It is found that the cyclic stability of these nanocomposites is enhanced due to the integration of MWCNTS and Cu nanoparticles with PPy polymer. The Cu/PPy/MWCNTs nanocomposites retained 91% of their specific capacitance even after 1000 cycles. The maximum energy density of 19.89 Wh/kg and maximum power density of 4479.71 W/kg at the scan rate of 200 mV/s were also measured for the Cu/PPy/MWCNTs nanocomposite. Our study thus indicates that the prepared Cu/PPy/MWCTs nanocomposite could be a potential candidate for application in supercapacitor and hybrid type storing devices.

Synthesis of Colloidal Copper (Cu) Nanoparticles by Pulse Laser Ablation Method (Nd:YAG 1064 nm) in Deionized Water

Copper nanoparticles are usually used for various fields, such as medical, energy, environmental, and others. Copper nanoparticles were successfully synthesized in deionized water (DIW) using the 1064 nm ND:YAG pulse laser ablation method at 85 mJ energy. The resulting colloidal nanoparticles are greenish in color. This study investigates the use of DIW liquid medium that can survive one day after being synthesized or changed. The result is that there is a change in the colloidal photo of copper (Cu) nanoparticles shortly after being synthesized and one day after being synthesized. There is a change in color to become clearer after the colloid is left alone for one day. Not only did the colloid photo change, but the absorbance of the UV-Vis testing of the Cu nanoparticle colloid also changed. Changes in UV-Vis absorption in colloids immediately after being synthesized and after colloids were left standing for one day decreased from 1.175 to 0.561, and experienced a shift in wavelength from 222.96 nm to 223.07 nm. The morphology of Cu nanoparticles was seen using FESEM with a spherical shape. The average size distribution of Cu nanoparticles is about 56.7 nm.

Highly Active and Efficient Cu@SiO2 Catalyst: Enabled Nucleophilic and Electrophilic Activation of Active Methylene Compounds

AbstractThe utility of copper is strikingly afforded due to the variable oxidation state being widely used in various organic reactions. The copper‐catalyzed C−C bond formation with active methylene compounds are a straightforward approach with widespread uses in synthetic organic chemistry. A significantly lower amount of Cu‐supported SiO2 catalyst was synthesized through sol‐gel method. The microscopy analysis reveals the formation of spherical morphology and the uniform distribution of Cu nanoparticles of 2.5 nm size. Furthermore, copper was found in Cu+2 state by XPS analysis. The NH3‐TPD analysis estimated the 0.092 mmol/g acidic sites. The synthesized multifunctional catalyst was used for gabapentin intermediates through a series of active methylene compounds through tandem organic reactions. The catalyst gave excellent conversion (99%) and selectivity (99%) of the desired product. The catalyst was found to be highly stable and recycled for six cycles without losing any activity and selectivity to the reaction product.

A Cu Nanoparticles‐Assisted‐Catalysis Method Enables Controllably Direct Growth of Graphene Transparent Conductive Films on SiO2 Nanospheres Antireflection Layer

AbstractThe regulation of catalyst distribution is crucial to enhance transmittance of graphene transparent conductive films (TCFs) maintaining their high electrical properties in the chemical vapor deposition (CVD) process. We successfully regulated the distribution of Cu nanoparticles (NPs) and realized the controllable deposition of graphene on the insulating substrates coated with SiO2 nanospheres antireflection (SiO2 NSs AR). The graphene/SiO2 NSs AR composite TCFs prepared with optimized conditions have transmittance of 95.86 % and sheet resistance of 0.934 kΩ ⋅ sq−1. Compared with graphene TCFs with a whole coated distribution of Cu NPs, the optical properties of graphene/SiO2 NSs AR composite TCFs were significantly improved. Meanwhile, it can maintain a comparable or even lower sheet resistance. This method is easier‐operational, low‐cost and lays a foundation for preparing high‐quality graphene TCFs for future electronic devices.

Controllable direct growth and patterning of graphene based transparent and conductive films on insulating substrates via Cu nanoparticles assisted-catalysis method

To avoid the complex transfer progress of graphene with the traditional chemical vapor deposition (CVD) method, we have developed a Cu nanoparticles (NPs) assisted-catalysis CVD process to directly deposit graphene on insulating substrates. It allows to controllably grow graphene by atmosphere pressure CVD according to regulating the distribution of Cu NPs. The fundamental growth conditions have been systematically investigated and the obtained graphene has preferable photoelectrical performance. Compared with a whole coated distribution of Cu NPs on the substrate, the transmittance of controllably deposited graphene significantly increases by 8.25% with decreased sheet resistance simultaneously. We further regulated the distribution of Cu NPs on the insulating substrate with a designed mask and directly prepared the patterned graphene with good achievement. This approach provides a facile and cost-effective way to directly prepare high-quality patterned graphene on target substrates and opens up a novel idea for fabricating various functional electronic devices.

Exploring CuCrFeVTi system to produce high entropy alloys for high heat flux applications

• Cu-high entropy alloys for fusion applications have been produced by arc-melting. • The materials present a dendritic microstructure, with Cu and Ti segregation. • A distribution of Cu nanoparticles is formed inside the dendrites. • Massive nanoindentation, statistical analysis and BSE images have been combined. • The H and E of each phase and their effect into the microhardness were determined. Cu 5 Cr 35 Fe 35 V 20 Ti 5 , Cu 10 Cr 35 Fe 35 V 10 Ti 10 , Cu 15 Cr 35 Fe 35 V 5 Ti 10 and Cu 20 Cr 30 Fe 30 V 10 Ti 10 were produced by low-pressure arc-melting to evaluate the feasibility of developing reduced activation high entropy alloys containing copper. The materials present a dendritic microstructure and some Cu and Ti segregation in the as-cast condition, being the Cu 5 Cr 35 Fe 35 V 20 Ti 5 the most homogenous alloy. Copper particles, with a mean size of about 10 nm, are found distributed inside the dendrites. The volume fraction of the copper particles is ~ 7 times higher in the alloy with 5 at.% Cu content that in the alloy with 20 at.%, with values ranging from 22 ± 5 to 3 ± 2 particles/μm 2 . Combination of massive Berkovich nanoindentation, statistical analysis and analytical scanning electron microscopy, has been successful for determining the hardness and elastic modulus values of each phase and quantifying their contribution to microhardness values obtained by standard Vickers microindentation.

Low temperature and pressureless Cu-to-Cu direct bonding by green synthesized Cu nanoparticles

BackgroundLow temperature bonding is the key for developing advanced electronic packaging technique. While Cu is regarded as a promising material for interconnects with high conductivity, the oxidation issue during processing needs to be solved. MethodsIn this study, Cu-to-Cu direct bonding was achieved at low temperature without applying pressure by a green chemical method. Synthesized Cu nanoparticles (NPs) without capping agents were mixed with polyethylene glycol (PEG). Significant findingsAn iterating mechanism is proposed as Cu oxide catalyzing the decomposition of PEG, and the decomposed products further reduce the Cu oxide. Particle size and size distribution of Cu NPs were simply controlled by pH value of the reducing solution. A random close packing model proves that packing density of the pre-sintered Cu NPs directly correlates to bonding strength. Ductile fracture surface confirms the realization of well-sintered joints by a green process that can be applied to devices.

Preparation of PdAuCu/C as a Highly Active Catalyst for the Reduction of 4‐Nitrophenol by Controlling the Deposition of Noble Metals

AbstractThe reasonable control of the dispersion of noble metals is an important topic for heterogeneous catalysts. In this manuscript, PdCu/C, AuCu/C and PdAuCu/C were prepared by the galvanic reduction method to ensure that Pd and Au follow the distribution of Cu nanoparticles. The catalysts were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy‐dispersive spectrometer elemental mappings and lines scans. Both the Pd and Au had very high dispersion no matter whether they were introduced individually or simultaneously. The Pd and Au were distributed mainly on the Cu nanoparticles as evidenced by the energy‐dispersive spectrometer elemental mappings and lines scans. The reduction of 4‐nitrophenol was used as a model reaction for the prepared catalysts. PdCu/C and AuCu/C showed high activity for this reaction compared to the literature, and the activity could be further increased by the introduction of Pd and Au in an appropriate ratio at the same time. The normalized reaction rate reached 2.005 s−1 mM−1 for the PdAuCu/C‐2.0, in which the mole ratio of Pd to Au was 2.0.

Copper nanoparticles as nanofillers in an adhesive resin system: An in vitro study.

The incorporation of an antibacterial agent into an adhesive could improve its clinical performance. Some nanoparticles (NPs), including copper nanoparticles (Cu NPs), display an antibacterial effect. Therefore, Cu NPs could act as a nanofiller when added to an adhesive. The aim of this study was to evaluate the antibacterial activity, cytotoxicity and shear bond strength (SBS) of an experimental dental adhesive with Cu NPs. Different concentrations (0.0050 wt%, 0.0075 wt% and 0.0100 wt%) of Cu NPs were added to the adhesive. The distribution of Cu NPs in the polymer matrix was observed based on transmission electron microscope (TEM) images. The antimicrobial activity of the adhesive + Cu NPs was evaluated with the agar disk diffusion test against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Streptococcus mutans (S. mutans). The cytotoxicity assay was performed by means of the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method with human pulp cells (HPC). Additionally, the SBS tests were carried out (n = 31) and the modes of fracture were registered. The vestibular and lingual surfaces of each tooth were randomly assigned to the study groups (group I - control adhesive; group II - adhesive + 0.0100 wt% Cu NPs). The samples were statistically analyzed (p ≤ 0.05). The adhesive + 0.0100 wt% Cu NPs showed inhibition zones against the strains under study that were similar to, or slightly smaller than, the halos produced by chlorhexidine (CHX) and specific drugs for each strain (30 μg of cefotaxime against S. mutans and S. aureus, and 1.25/3.75 μg of sulfamethoxazole/ trimethoprim against E. coli). The control adhesive was moderately cytotoxic (relative cell viability of 36.7 ±0.8%), being more cytotoxic than Cu NPs themselves (58.3 ±0.1%). A significantly higher SBS was obtained for the adhesive + 0.0100 wt% Cu NPs (6.038 ±2.95 MPa) than for the control group (3.278 ±1.75 MPa). The modes of fracture in group I were almost equally distributed between adhesive and cohesive failures whereas in group II, the failure was mainly cohesive. The results of this study suggest that incorporating Cu NPs into an adhesive improves its SBS and provides it with antibacterial properties, without increasing its inherent cytotoxicity - 2 desirable characteristics for the dental adhesives of composites.

Application of a novel method for fabrication of graphene reinforced aluminum matrix nanocomposites: Synthesis, microstructure, and mechanical properties

In this study, the graphene reinforced aluminium matrix nanocomposite is fabricated through the combination of high energy ball milling (HEBM) and molecular level mixing (MLM) processes followed by spark plasma sintering (SPS) method. FTIR, XRD and FESEM analyses revealed that Cu/RGO nanocomposite was well synthesized by the MLM method with a uniform distribution of Cu nanoparticles on RGO surface. XRD and Raman spectroscopy showed that no Al4C3 phase was formed during the manufacturing process, but Al2Cu fine particles precipitated during the SPS treatment which were smaller in size and more uniform in distribution when RGO was used as reinforcement according to TEM analysis. Grain refinement of the nanocomposites was also investigated in the presence of RGO by EBSD method. The results showed that with increasing RGO content from 0 to 1 wt %, the coarse grained microstructure changed to bimodal microstructure. In addition, the mean grain size decreased from 3.9 to 1.6 μm, and dislocation density increased significantly with the increased RGO content. The SPS process also resulted in a nearly fully dense nanocomposite with a relative density higher than 99%. The investigation of mechanical properties of the sintered nanocomposite indicated an improvement of 79, 49 and 44% of yield strength, ultimate strength, and Vickers hardness, respectively, for only 1 wt % graphene containing nanocomposite in comparison to the unreinforced Al–4Cu alloy.

Amine-terminated ionic liquid modified graphene oxide/copper nanocomposite toward efficient lubrication

How to make full use of the synergistic effect between nanomaterials is of great significance for designing high-performance lubricating materials. Here, novel amine-terminated ionic liquid-modified graphene oxide (GO)/copper nanocomposite (IL-GO/Cu) is synthesized by facile liquid-phase method in which GO nanosheets and Cu nanoparticles are linked by 1-aminoethyl-3-methyl imidazolium nitrate ionic liquid through covalently grafting and electrostatic interaction. Of what interest is the homogeneous distribution of Cu nanoparticles on IL-GO plane/interlayers, possibly being endowed to excellent lubrication function. Results demonstrate that IL-GO/Cu nanocomposite with 0.08 wt% addition amount into polyethylene glycol (PEG 200) improves friction and wear resistance by up to 40.1% and 47%, respectively. Such performance characteristics mainly depend on the synergistic lubrication, including not only the boundary lubrication film composed of adsorbed/transfer/tribo-chemical film, but also the “third body” from the additive and its wear debris with Fe/Cu nanocrystals-embedded graphene-like structure. This paper offers an attractive strategy for fabricating graphene-based nanocomposite toward real-world application in tribology. • IL-GO/Cu composite with a sandwich-like structure is prepared via interlinkage of GO and reduced-Cu NPs by amine-terminated ILs. • Cu NPs with a diameter of 15~20 nm are evenly distributed across basal plane/interlayers. • As-prepared composite possesses high thermal-stability, good dispersion and excellent mechanical properties. • IL-GO/Cu composite as a high-performance lubricant depends on the synergies of boundary lubrication film and wear debris with sandwich-like structure.

Hard template-induced internal solidification synthesis of Cu NPs- supported glutaraldehyde-crosslinked polyethyleneimine-modified calcium alginate beads with enhanced catalytic activity

The development of a sustainable catalyst with high catalytic activity and easy recovery property is an important subject in the field of heterogeneous catalysis. In this work, we developed a hard template-induced internal solidification procedure for preparation of ultrafine metal nanoparticles (NPs) supported on GLA-PEI-CA beads. During the fabrication process, CaCO3 NPs had a dual function, not only serviced as a hard template to adjust the structure of the as-prepared catalyst, but also as an indirect crosslinking agent to obtain hydrogel beads. The resulting beads were characterized using FT-IR, XRD, BET, SEM, TEM, EDS and XPS. The results revealed that Cu NPs with a narrow size distribution in 2–3 nm were uniformly immobilized on the surface of GLA-PEI-CA-1 beads with high specific surface area and well-developed hierarchical pore structure. As a result, the Cu@GLA-PEI-CA-1 beads exhibited remarkably catalytic activity and high stability, with more than 90% conversion within 10 successive cycles, towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 in aqueous solution. The result showed that the Cu@GLA-PEI-CA-1 catalyst displayed high kinetic responses with a kinetic reaction rate constant of 1.60 × 10−2 s−1, which was higher than that of Cu@GLA-PEI-CA-0 (without CaCO3 template) and Cu@GLA-CA-1 (without PEI coating). The enhanced catalytic performance was resulted from homogeneous distribution of Cu NPs along with the tailored microstructure and the hydrophilic surface of the support. Additionally, the dynamic catalytic experiment was conducted to investigate the catalytic performance of Cu@GLA-PEI-CA-1 beads as the catalyst. We expected that this work could provide a new and effective strategy to design highly efficient catalysts for various catalytic reactions.

Preparation of ultrafine grained copper nanoparticles via immersion deposit method

Today, the exploration about synthesis of nanoparticles is much of interest to materials scientists. In this work, copper nanoparticles have been successfully synthesized by immersion deposit method in the absence of any stabilizing and reducing agents. Copper (II) sulfate pentahydrate as precursor salt and distilled water and Ethylene glycol as solvents were used. The copper nanoparticles were deposited on plates of low carbon steel. The effects of copper sulfate concentrations and solvent type were investigated. X-ray diffraction, scanning electron microscopy and UV–Visible spectroscopy were taken to investigate the crystallite size, crystal structure, and morphology and size distribution and the growth process of the nanoparticles of obtained Cu particles. The results indicated that the immersion deposit method is a particularly suitable method for synthesis of semispherical copper nanoparticles with the crystallites size in the range of ~22 to 37 nm. By increasing the molar concentration of copper sulfate in distilled water solvent from 0.04 to 0.2 M, the average particles size is increased from 57 to 81 nm. The better size distribution of Cu nanoparticles was achieved using a lower concentration of copper sulfate. By increasing the molar concentration of copper sulfate in water solvent from 0.04 to 0.2, the location of the SPR peak has shifted from 600 to 630 nm. The finer Cu nanoparticles were formed using ethylene glycol instead water as a solvent. Also, the agglomeration and overlapping of nanoparticles in ethylene glycol were less than that of water solvent.

Metal–organic framework-driven copper/carbon polyhedron: synthesis, characterization and the role of copper in electrochemistry properties

A facile synthetic strategy has been developed to harvest copper/carbon polyhedron (Cu/C-X, X = 1, 2, 3) with varisized Cu nanoparticles contained in porous carbon matrix from the pre-fabricated Cu-BTC (BTC = benzenetricarboxylic acid), of which Cu/C-1 has good structural integrity and smaller embedded Cu nanoparticles. The Cu/C-3 is acid treated from Cu/C-1 which possesses integrated structure and numerous newborn pores by removal of in situ Cu nanoparticles. Benefited from integrated morphology and newborn porous structure, the Cu/C-3 exhibits enhanced electrochemical double-layer capacitance (Cdl, 19.4 mF cm−2), which is 2.7- and 12.9-fold as large as that of Cu/C-1 and Cu/C-2, respectively. Further, electrochemical measurements indicate that the electrochemical properties of Cu/C samples highly depend on porosity, structural integrity and the distribution of Cu nanoparticles. In addition, it is found that proper distribution and size of Cu nanoparticles embedded into carbon matrix are beneficial to faster electron transport and mass transfer. This work presents a facile synthesis method of novel Cu/C polyhedron with homogeneous distributed Cu nanoparticles, which could be further investigated in the application of high-performance electrode for supercapacitors.

The use of biodegradable polymers for the stabilization of copper nanoparticles synthesized by chemical reduction method

Copper nanoparticles were synthesized by a convenient and rapid chemical reduction method in ambient condition using $$\hbox {Cu}(\hbox {NO}_{3})_{2}{\cdot } 3\hbox {H}_{2}\hbox {O}$$ as a precursor, hydrazine hydrate as reducing agent and deionized water as solvent. The product was characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. However, agglomerated copper nanoparticles were obtained by this chemical reduction method. Hence, the effects of three polymers of polyvinyl pyrrolidone, polyethylene glycol (PEG) and starch as stabilizers on the size and size distribution of Cu nanoparticles were investigated. According to the results, smallest copper nanoparticles (30–50 nm) with a narrow size distribution were obtained using PEG as the stabilizing polymer. Zero-valent copper nanoparticles with high purity were obtained by this method and there was no peak related to the oxidized impurities such as CuO and $$\hbox {Cu}_{2}\hbox {O}$$ in the XRD and UV–Vis studies, both in the presence and in the absence of stabilizer. On the other hand, by this method, zero-valent copper nanoparticles were obtained in the absence of any anti-oxidant agent and any inert gas flow. The effects of synthesis parameters including initial concentration of precursor, polymer concentration and the reaction temperature on the size and size distribution of copper nanoparticles were investigated using the UV–Vis analysis to determine the optimum synthesis conditions.

Influence of Cu Nanoparticles on Microstructure and Mechanical Properties of Sn0.7Ag0.5Cu-BiNi/Cu Solder Joint

The influence of Cu nanoparticles addition on microstructure and mechanical properties of Sn0.7Ag0.5Cu-BiNi/Cu solder joint after reflow and isothermal aging has been investigated in this study. Experimental results indicate that the addition of Cu nanoparticles suppresses the growth of intermetallic compound (IMC) layer at the interface after reflow and aging. Moreover, the bulk solder appears with refined microstructure after adding Cu nanoparticles. In addition, solder joints containing Cu nanoparticles display higher microhardness due to the dispersive distribution of Cu nanoparticles as well as the refined IMC particles. The addition of 0.1% Cu nanoparticles can improve the microhardness by 16% compared with the noncomposite. However, the existing porosity in the solder exerts a negative effect on microhardness and shear strength. The mechanism of porosity formation has been discussed in detail. Porosity increases markedly with increasing Cu nanoparticles proportion.

Size-Selective Cu Nanocrystals Growth on Single and 2-3 Layers Graphene Films.

Cu nanoparticles decorated CVD growth single layer and 2-3 layers graphene films have been synthesized by sputtering deposition and annealing process. The wrinkles were observed on single layer graphene due to high annealing temperature (700 degrees C) and rapid cooling process, which were proved by HRSEM and Raman spectra. Smaller mean diameter and narrower size distribution of Cu nanoparticles were observed on 2-3 layers graphene film than that on single layer graphene. The large particles grow at the expense of small particles, and the particle growth was governed by the Ostwald ripening process.