Copper Nanoparticle Composites Research Articles

Hydrogen Boride Sheets and Copper Nanoparticle Composites as a Visible‐Light‐Sensitive Hydrogen Release System

AbstractHydrogen boride (HB) sheet is a new class of 2D materials comprising hydrogen and boron, synthesized through ion‐exchange and exfoliation techniques. HB sheets can release hydrogen (H2) under light irradiation and is predicted to be a promising H2 storage material. However, its application is limited to the UV region. One approach to enable a visible‐light‐driven system is the utilization of plasmonic metallic nanoparticles. The present study reports H2 release from copper (Cu) nanoparticle‐modified HB sheet (HB/Cu) under visible‐light irradiation. Copper nanoparticles possess unique and strong plasmonic responses in the visible‐light range, making them ideal light absorbers in this system. HB/Cu nanocomposites are synthesized using a simple mixture of copper acetate and HB sheets in acetonitrile, where HB sheets reduced copper ions to metal copper nanoparticles. The photoirradiation results shows that HB/Cu nanocomposites released more H2 than the bare HB sheets under visible‐light irradiation. This is probably due to the plasmonic photothermal effect of copper metal, which enhances H2 generation from the HB sheets. This material offers a viable and cost‐effective approach for developing visible‐light‐sensitive systems.

A sustainable approach to prepare green synthesis of copper nanoparticles of Bauhinia variegata & Saussurea lappa: Unveiling in-vitro anti-obesity applications

Nanoparticles have different shapes and sizes between the range of 1–100 nm, which show advantages for stabilizing compounds, higher carrier capacity, and lower costs. Metal nanoparticles such as copper, gold, silver, and zinc are favorable components for various applications due to their interesting properties. In the present study, nanoparticles were synthesized by reduction with flower extracts of Bauhinia variegate &Saussurea lappa that were used to stabilize the copper nanoparticles. Furthermore, the characterization of plants synthesized copper nanoparticles was carried out through UV–visible dynamic light scattering. Additionally, morphological characterization of nanoparticles was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed the elemental composition of copper nanoparticles. Powder X-ray diffraction was conducted for the analysis of crystallinity, purity, and crystal size of plant-synthesized copper nanoparticles. The average particle size was evaluated and exhibited the particle size at the peak of 8.721 nm and 98.03 nm for flower extracts of Bauhinia variegate &Saussurea lappa copper nanoparticles. The Fourier Transform Infrared spectrum was taken to scrutinize the various functional groups that were responsible for the reduction of the copper ions. The antimicrobial results against the bacterial strains with the positive test results of the zone of inhibition were for Bauhinia variegate (17 mm, 18 mm, 19 mm, and 18 mm) and Saussurea lappa (17 mm, 19 mm, 18 mm, and 18 mm) respectively for plants synthesized copper nanoparticles against the Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa. Lipase inhibition assay and Amylase inhibition assay with different concentrations (20 μg/mL to 100 μg/mL) for Bauhinia variegate &Saussurea lappa (12.34 %–59.67 % and 10.50 %–47.01 %) and (34.52 %–89.02 % and 22.34 %–56.45 %) confirmed the anti-obesity and anti-diabetic activities of plants extract synthesized copper nanoparticles.

Investigation of optical properties and antibacterial activity of chitosan copper nanoparticle composites

ABSTRACT Chitosan (Cs) doped with different proportion of copper nanoparticles (CuNPs) has been prepared using the casting method in an oven at T = 333 K. The optical properties of Cs/CuNPs have been investigated using different techniques such as, UV-Vis and FTIR spectroscopy. Many optical parameters such as optical band gap energy, oscillation energy, dispersion energy and lattice dielectric constant of all samples have been estimated. FTIR spectra of Cs and Cs/CuNPs have been investigated and the results revealed that, a broadness of OH groups in Cs/CuNPs has been observed. XRD measurements showed that, average of the particle size is approximately ~ 8.11 nm. Measurements of swelling showed that, the maximum swelling decreases linearly with increasing concentration of copper nanoparticles. The antibacterial activity of chitosan and Cs/CuNPs samples has been investigated against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia colii). The results revealed that, irradiated samples with UV-irradiation exhibited a greater activity in comparison to the non-irradiated samples.

Biopolymer-Assisted Manufacturing of Aluminum–Copper Nanoparticle Composites with Enhanced Sinterability

Sintering is an essential step to obtain bulk components from aluminum powders, which enables powder metallurgy-based fabrication methods such as additive manufacturing technologies. Copper (Cu) ca...

Fabrication of electrospun antibacterial PVA/Cs nanofibers loaded with CuNPs and AgNPs by an in-situ method

Scientific efforts have been made to study and develop the efficient product to be used beyond conventional antibiotic treatments against bacteria and funguses mainly in the wound dressing. Therefore, in this innovative study, the authors investigated the development of hybrid nanofibers of chitosan/polyvinyl alcohol/nano-hydroxyapatite with the composition of copper nanoparticles for wound dressing potential. Therefore, copper/silver with ratio 1:1, copper nanoparticles and silver nanoparticles were chosen as variable to comparison the biocompatibility and antibacterial properties between copper and silver nanoparticles. The nanoparticle loaded to nanofibers by the in-situ method to prepare the chemical bonding between nanofibers and nanoparticles. All characterization results were appreciable for successful synthesis of nano-hydroxyapatite in the nanofibers matrix and loading metallic nanoparticles with chemical reactions between nanoparticles and nanofibers, due to OH deformation of Cs/PVA/nHA nanofibers and reaction with nano-particles. Although the in-vitro results showed PVA/Cs nanofibers loaded with Cu/Ag nanoparticles, is the most appropriate sample for wound dressings because it has very good inhibition zone against the gram negative and gram positive bacteria. This composite also has the good biocompatibility and no toxicity which is good sign for cell attachment and biocompatibility.

Compositional disorder and its effect on the thermoelectric performance of Zn3P2 nanowire–copper nanoparticle composites

Recent studies indicated that nanowire format of materials is ideal for enhancing the thermoelectric performance of materials. Most of these studies were performed using individual nanowires as the test elements. It is not currently clear whether bulk assemblies of nanowires replicate this enhanced thermoelectric performance of individual nanowires. Therefore, it is imperative to understand whether enhanced thermoelectric performance exhibited by individual nanowires can be extended to bulk assemblies of nanowires. It is also imperative to know whether the addition of metal nanoparticle to semiconductor nanowires can be employed for enhancing their thermoelectric performance further. Specifically, it is important to understand the effect of microstructure and composition on the thermoelectric performance on bulk compound semiconductor nanowire–metal nanoparticle composites. In this study, bulk composites composed of mixtures of copper nanoparticles with either unfunctionalized or 1,4-benzenedithiol (BDT) functionalized Zn3P2 nanowires were fabricated and analyzed for their thermoelectric performance. The results indicated that use of BDT functionalized nanowires for the fabrication of composites leads to interface-engineered composites that have uniform composition all across their cross-section. The interface engineering allows for increasing their Seebeck coefficients and electrical conductivities, relative to the Zn3P2 nanowire pellets. In contrast, the use of unfunctionalized Zn3P2 nanowires for the fabrication of composite leads to the formation of composites that are non-uniform in composition across their cross-section. Ultimately, the composites were found to have Zn3P2 nanowires interspersed with metal alloy nanoparticles. Such non-uniform composites exhibited very high electrical conductivities, but slightly lower Seebeck coefficients, relative to Zn3P2 nanowire pellets. These composites were found to show a very high zT of 0.23 at 770 K, orders of magnitude higher than either interface-engineered composites or Zn3P2 nanowire pellets. The results indicate that microstructural composition of semiconductor nanowire–metal nanoparticle composites plays a major role in determining their thermoelectric performance, and such composites exhibit enhanced thermoelectric performance.

Preparation of copper–silicon dioxide nanoparticles with chemical vapor synthesis

Atmospheric pressure chemical vapor synthesis was used to produce copper nanoparticle composites in an amorphous silicon dioxide, i.e., either copper nanoparticles coated with amorphous silicon dioxide or copper nanoparticles embedded in amorphous silicon dioxide matrix. Synthesized metal–organic copper(I) complex was used as a precursor that provided well-defined ratio (1:2) of copper and silicon. The thermal decomposition of the Cu(I) complex molecule leads to homogenous nucleation and formation of copper nanoparticles which are subsequently coated with Si/SiO2 in the gas phase. The decomposition was greatly enhanced when reductive atmosphere, i.e., H2/N2 10 v% were used instead of pure nitrogen. A narrow size distribution with the geometric mean diameter of the particle agglomerates around 30 nm was observed while the primary size of the copper core particles was around 5 nm.

Nonlinear optical properties of Cu nanoparticle composites fabricated by 60 keV negative ion implantation

Steady-state absorption and transient nonlinear response of copper nanoparticle composites in LiNbO 3 were investigated in the visible range. Negative ion implantation at 60 keV was applied to fabricate the Cu nanoparticles in the insulators. The surface plasmon band in steady-state absorption spectra in LiNbO 3 resulted from formation of nanoparticles and showed a broadening and shift to red in comparison with the band in amorphous SiO 2 and MgO · 2.4(Al 2O 3). Transient absorption was measured with the technique of pump–probe femtosecond spectroscopy. The transient bleaching band also shifted with the steady-state plasmon peak and recovered within a picosecond. The transient spectrum of the composites in LiNbO 3, reflects the energy transfer in nanoparticles, overlaps with the optical damage in the matrix. The electron–phonon coupling constant of Cu nanoparticles in LiNbO 3 yielded a value of g=2.4×10 16 W/m 3 K.

Optical properties of nanoparticle composites in insulators by high-flux 60 keV Cu − implantation

Steady-state and transient optical absorption of copper nanoparticle composites, fabricated by ion implantation, was studied. Cu nanoparticles were formed in SrTiO 3 ( n=2.25 at 600 nm). The surface plasmon band in steady-state absorption spectra resulted from formation of nanoparticles in SrTiO 3 and shifted to red in comparison with the band in amorphous SiO 2 and MgO 2.4(Al 2O 3). Transient absorption was measured with pump–probe femtosecond spectroscopy. The transient response of the composites in SrTiO 3 results from electron dynamics in nanoparticles and from radiation-induced defects in the matrix. The former responds in a few picoseconds, while the latter remains more than several ten picoseconds.

Copper Nanoparticle Composites in Insulators by Negative Ion Implantation for Optical Application

Steady-state and laser-induced transient surface plasmon bands of copper nanoparticle composites, fabricated by ion implantation, were studied by optical measurements. Negative ion implantation has been applied to generate the Cu nanoparticles with a narrow distribution in amorphous SiO2, MgO2.4(Al2O3) and LiNbO3 with various refractive indices. The Cu nanoparticles were embedded within a depth of 100 nm by implantation of 60 keV Cu−. The surface plasmon band in steady-state absorption spectra resulted from formation of nanoparticles in the various substrates and shifted to red with increasing refractive index of the matrix. Transient absorption was measured with the technique of pump-probe femtosecond spectroscopy. The transient bleaching band also shifted in parallel with the steady-state plasmon resonance. The bleaching recovered in several picoseconds due to energy transfer from the excited electron system to the phonon system via the electron-phonon interaction. The electron-phonon coupling constant, g, of Cu nanoparticles in amorphous SiO2 was obtained to be a value of 2.4×10 16 W/m 3 K.

Optical transient resonance of copper nanoparticle composites synthesized by negative ion implantation

Steady-state optical absorption and nonlinear transient resonance have been studied for Cu nanoparticle composites, fabricated in magnesium aluminate spinel by high-current negative ion implantation. The implantation was conducted at high ion fluxes of 60 keV up to a total dose of 3×10 16 ions/cm 2. Optical absorption strongly depended on dose rate, ranging from 1 to 100 μA/cm 2. The dose rate dependence of the absorption spectra around the surface plasmon resonance behaved analogously to that of a-SiO 2, though the radiation-induced absorption band depended on stoichiometry of the spinel. The spectral shape of transient absorption at various dose rates is similar but the bleached plasmon band shifts is in parallel with the steady-state surface plasmon resonance. The dose rate chiefly influences dielectric properties of a spinel matrix but not that of particles.