Effects Of Cu Nanoparticles Research Articles

Efficient CO2 reduction under visible light: Synergistic effects of Cu nanoparticles and Ni single atoms

Photocatalytic reduction of CO2 is a considerable method to alleviate global warming and energy shortage. In this work, CoAl-LDH/Ni1CuNP nitrogen-doped carbon composites (CA/Ni1CuNP N-C) can efficiently reduce CO2 into CO, CH4, and C2H6 under visible light. In situ characterization techniques and theoretical calculations were employed to investigate the CO2 evolution pathway and photocatalytic mechanism. The synergistic interaction of Cu nanoparticles and Ni single-atom sites accelerated the photogenerated charge separation and facilitated the adsorption properties of key intermediates. As a result, the yields of CH4 and C2H6 on CA/Ni1CuNP N-C were achieved up to 35.245 and 25.328 μmol g−1 h−1 with electron selectivity of 40.24% and 50.61%, respectively. This work is instructive for using metal nanoparticles to optimize single-atom catalysts to promote their catalytic activity.

Enhancing the thermoelectric performance of CoSb3-based skutterudite by decoupling the electrical and thermal properties by embedding Cu nanoparticles

Co0.91Ni0.09Sb3 embedded with Cu nanoparticles (NPs) was synthesized by applying a hydrothermal process followed by spark plasma sintering. The effects of Cu NPs on the electrical and thermal transport properties of the Co0.91Ni0.09Sb3 matrix were investigated in the temperature range of 303–773 K. Cu NPs introduced into the Co0.91Ni0.09Sb3 matrix slightly decreased the electrical conductivity and significantly enhanced the Seebeck coefficient by the energy filtering effect, leading to an improved power factor at 773 K. Furthermore, a significant decrease in the thermal conductivity was realized by increasing the number of grain boundaries. These favorable effects contributed to the improvement in ZT to a value ~57% higher than that of pristine Co0.91Ni0.09Sb3. The highest ZT value of 1.02 was achieved by incorporating 4.5 wt% of Cu NPs in Co0.91Ni0.09Sb3 at 773 K. Thus, decoupling the electrical and thermal transport properties of thermoelectric materials is a viable strategy for optimizing the ZT value.

Localized surface plasmon resonance of copper nanoparticles improves the performance of quasi-two-dimensional perovskite light-emitting diodes

Plasmonic nanoparticles (NPs) based on noble metals are often used for improving the performance of optoelectronic devices. Widescale use of these nanostructures for commercial applications, however, has been hampered by their high material cost. Herein, we use copper (Cu), which is more abundant and low-cost, to synthesis NPs; the NPs are further capped with polyvinylpyrrolidone to improve their ambient stability. The as-prepared Cu NPs are incorporated into quasi-two-dimensional perovskite light-emitting diodes for increasing the device efficiencies. The luminous efficiency can be improved up to 115%. From the photoluminescent studies, we attribute the device enhancement to the plasmonic effects of Cu NPs. We anticipate that the cost-effective polymer-capped Cu NPs may trigger demand of plasmonic nanostructures for use in commercial optoelectronic devices.

Plasmonic effects of copper nanoparticles in polymer photovoltaic devices for outdoor and indoor applications

The use of metal nanoparticles (NPs) that can trigger localized surface plasmon resonance (LSPR) is an effective method for improving the performance of organic photovoltaics (OPVs). Currently, most plasmonic NPs are based on noble metals, including gold and silver; their high cost limits their commercial applications in the cost-effective OPVs. Herein, copper (Cu) NPs, which are more abundant and cheaper, are adopted to fabricate OPVs. To avoid oxidation of Cu NPs, they are positioned at the cathode interface, so that their fabrication could be implemented in an inert environment. The resulting OPVs exhibited improved power conversion efficiencies (PCEs) under illumination at 1 sun, and the device enhancement could be attributed to the LSPR effects of Cu NPs. Further, their potential to enhance the performance of OPVs under indoor lighting conditions is evaluated. The enhancement factor of PCEs was higher, while the light source had a lower color temperature. It could be due to the fact that the main plasmonic band of the Cu NPs is localized in the red spectral range. The results reveal the consideration of matching between the LSPR spectral range and the emission spectra of the artificial light sources is very critical for indoor applications.

Effects of nanoparticles on properties and interface reaction of Sn solder for microelectronic packaging

In this study, the effects of Cu nanoparticles on the melting characteristics, wettability, interfacial reaction and mechanical properties of [Formula: see text]–[Formula: see text] [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] composite solders were investigated. Results show that the properties of the composite solder containing Cu nanoparticles were improved effectively. With the addition of Cu nanoparticles, the melting point of [Formula: see text]–[Formula: see text] solder decreased significantly, and the spreading area and the shear strength were increased by 10.3% and 23.2%, respectively. For the performance, the optimal addition of Cu nanoparticles was 0.7%. In addition, the growth of interfacial intermetallic compounds in [Formula: see text]–[Formula: see text] solder joints was inhibited by adding Cu nanoparticles.

Preparation of Cu nanoparticles fixed on cellulosic walnut shell material and investigation of its antibacterial, antioxidant and anticancer effects

In this study, antibacterial, antioxidant, and anticancer effects of Cu nanoparticles (CuNPs) fixed on cellulosic walnut shell material were investigated. Firstly, three types of walnut shell-supported copper nanoparticles with various sizes (CuNP-WS1 15–22 nm, CuNP-WS2 60–80 nm and, CuNP-WS3 aggregated of metallic nanoparticles) were synthesized. Antibacterial properties of CuNPs were studied on three strains of bacteria; Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes. DPPH (1, 1-Diphenyl-2-picrylhydrazyl) method was used to examining antioxidant properties. Cytotoxic effects of the synthesized nanoparticles on the cancer cell line were studied. Antimicrobial properties of CuNPs showed that these nanomaterials affect both Gram-positive and Gram-negative bacteria. The antioxidant properties of CuNPs increased significantly by increasing the concentration to 10%. CuNPs appeared to have a dose-dependent cytotoxic effect on K562 cells. However, the IC50 of the synthesized nanoparticles against the K562 (25.24 ± 5 μg/mL) cancer cells was lower significantly (P < 0.01) of the IC50 of these compounds against PBMCs (42.54 ± 6.2 μg/mL).

Theoretical calculations for localized surface plasmon resonance effects of Cu/TiO2 nanosphere: Generation, modulation, and application in photocatalysis

The localized surface plasmon resonance (LSPR) is considered as one of the effective strategies to broaden the spectral absorption range and improve quantum conversion efficiency or photocatalyst. Because of low-cost and LSPR absorption peaks in the visible-light region, Cu-based plasmonic photocatalysts have attracted concern in recent years. However, the mechanisms of generation, modulation, and application of LSPR effects of Cu nanoparticles are still insufficient. To this regard, by using finite-difference time-domain simulations and density functional theory calculations, the intrinsic mechanism of LSPR in the system of Cu nanosphere loaded onto TiO2 nanosphere has been systematically analyzed. When Cu nanosphere is gradually sinking into TiO2 nanosphere to form core-shell configuration, the LSPR absorption peaks is gradually red-shifting and separated from the interband region of metallic Cu nanosphere. The interfacial electronic states are the root of enhancement and red-shifting of LSPR absorption peaks in Cu/TiO2 nanospheres. What's more, the LSPR effects of different Cu/TiO2 nanosphere configurations are highly susceptible to the dielectric media with high refractive index, the direction of incidence light, and environmental media. The embedding configuration of Cu/TiO2 nanospheres is predicted to present outstanding photocatalytic performance, owing to less affected by the incident direction of light, effectively excited LSPR wavelength and local electric field, and more reaction sites for photo-redox reaction. The findings in the present work provide a convenient and efficient approach to screen plasmonic photocatalysts for efficient solar energy conversion.

Theoretical Calculation of Optical Properties of Copper NANO PARTICLES

Objectives: In this work the PLASMONIC effects of Cu NANO particles with varying particle sizes and surrounding mediums, such as PEDOT: PSS layers of organic Bulk-HETEROJUNCTION (BHJ) solar cells and silica were investigated. Methods/Statistical Analysis: For this work the optical properties of Cu NANOPARTICLES with different sizes (by varying the particle diameter from 20 to 100 nm) and when surrounded by different mediums (dielectric constant in interval 1.49 to 7) were investigated in the wavelength range 300-900 nm. The Mie theory was used to analyze the light scattering and extinction efficiencies. Findings: The results show that the particle size and dielectric constant of the medium are the key factors that directly influence the PLASMONIC enhancements in the samples. At a wavelength more than 550 nm, there is a second peak of the resonance peaks, as the Cu NANO particle size increases and the efficiency peak slightly shifts to a longer wavelength. The wavelength of the resonance peak was found to haven on-linear dependence on the dielectric constant of the surrounding medium. In addition, the linear dependence of the maximum of the extinction efficiencies on the dielectric constant of the surrounding medium at a fixed particle radius was observed. Application/ Improvements: The Localized Surface PLASMON Resonance (LSPRs) exhibited by noble metal NANOPARTICLES, such as Au, Ag and Cu, leads to strong enhancements on the local electromagnetic fields surrounding the NANOPARTICLES. Keywords: Cu NANOPARTICLE, Localized Surface PLASMON Resonance, Mie Theory, PLASMONIC Enhancements

Magneto-Nanofluid Dynamics in Convergent-Divergent Channel and its Inherent Irreversibility

The effects of Cu-nanoparticles on the entropy generation of steady magnetohydrodynamic incompressible flow with viscous dissipation and Joule heating through convergent-divergent channel are analysed in this paper. The basic nonlinear partial differential equations are transformed into a system of coupled ordinary differential equations using suitable transformations which are then solved using power series with Hermite- Padé approximation technique. The velocity profiles, temperature distributions, entropy generation rates, Bejan number as well as the rate of heat transfer at the wall are presented in convergent-divergent channels for various values of nanoparticles solid volume fraction, Eckert number, Reynolds number and channel angle. A stability analysis has been performed for the shear stress which signifies that the lower solution branch is stable and physically realizable, whereas the upper solution branch is unstable. It is interesting to remark that the entropy generation of the system increases at the two walls as well as the heat transfer irreversibility is dominant there whereas the fluid friction irreversibility is dominant along the centreline of the channel.

Effects of copper nanoparticles in porous TiO2 coatings on bacterial resistance and cytocompatibility of osteoblasts and endothelial cells

Copper (Cu) has garnered increasing interest due to its excellent antimicrobial activity and important roles in human metabolism. Although the biological effects of Cu have been studied, the effects of Cu nanoparticles (NPs) on cell behavior are not well understood. In this study, porous TiO2 coatings doped with different amounts of Cu NPs (designated as 0 Cu, 0.3 Cu, and 3.0 Cu) are deposited on titanium by micro-arc oxidation (MAO). The Cu NPs coated samples exhibit excellent antibacterial activity against Staphylococcus aureus (S. aureus). In vitro cytocompatibility evaluation discloses that 0 Cu and 0.3 Cu have no toxicity to osteoblasts but 3.0 Cu shows cytotoxicity. 0.3 Cu promotes proliferation and adhesion of osteoblasts and enhances extracellular matrix mineralization (ECM), but has little effects on the alkaline phosphatase activity (ALP) and collagen secretion. Surprisingly, the Cu NPs coated samples show a different behavior with endothelial cells. Both 0.3 Cu and 3.0 Cu show no cytotoxicity on endothelial cells and promote cell proliferation. Production of nitric oxide (NO) and secretion of vascular endothelial growth factor (VEGF) by the endothelial cells are observed from the Cu NPs doped TiO2 coatings.

Natural convection of Cu–water nanofluid near water density inversion in horizontal annulus with different arrangements of discrete heat source – Sink pair

In this paper, natural convection heat transfer is studied in two-dimensional horizontal concentric cylindrical annulus with discrete source-sink pairs. The effects of Cu nanoparticles on natural convection of water near its density maximum were considered in numerical simulations. Geometry consisting of two hot and cold sources (constant temperature) with different arrangements and the remained parts were assumed to be adiabatic. The governing equations were formulated using both the Boussinesq (B) and non-Boussinesq (NB) homogenous models and were solved on a non-uniform mesh using a pressure-based finite volume method. The computations were carried out for Pr=13.31, Rayleigh number from 104 to 5×105 and volume fraction of nanoparticles from 0 to 0.08. This work with pure fluid and nanofluid was validated by previous studies and the results were shown in three cases under investigation. The results were presented from streamlines and isotherms flow field, local and average Nusselt number. It was found that different arrangements by different angles and density inversion affected founding best state of heat transfer in each case and general enhancement of heat transfer was obtained by adding volume fractions of nanoparticles, so average Nusselt number increased and an optimum design was also found. It was concluded that the B approximation in comparison to NB approximation gave rise to the higher heat transfer rate. The findings showed that which of cases was applicable to optimization design in industry and especial in heat exchanger.

Near-IR Photoluminescence of Pr/Cu/Sn Tridoped Phosphate Glass: Nonplasmonic Material System Versus Plasmonic Nanocomposite

An optical spectroscopy study of Pr2O3, CuO, and SnO tridoped barium phosphate glass prepared by the melt-quenching technique has been carried out, emphasizing near-infrared (IR) emission properties. The material is studied in its nonplasmonic state (as synthesized) and plasmonic form (heat-treated), aiming to elucidate the effects of Cu nanoparticles. The data indicate that Cu+ ions and Sn centers are stabilized in the melt-quenched glass. Broad ultraviolet excitations of both species can lead to near-IR emission of Pr3+ ions via energy transfer. The plasmonic nanocomposite is produced upon heat treatment as Sn2+ reduces Cu+ to Cu0 atoms, ultimately precipitating as Cu nanoparticles sustaining the surface plasmon resonance. Consequently, depletion of primarily Cu+ modified the ultraviolet excitation properties for the sensitized near-IR Pr3+ emission. Further, suppression of the Pr3+ emission from near-IR emitting states 1D2 and 1G4 was observed in the Cu nanocomposite in accord with a “plasmonic diluent” role of the nanoparticles.

The toxicity, ways of exposure and effects of Cu nanoparticles and Cu bulk salts on different organisms

Nanotoxicology is projected as an emerging branch of toxicology to address the gaps in knowledge and adverse health effects likely to be caused by nanomaterials. This branch of nanotoxicology would make an important contribution to the development of a sustainable nanotechnology and covers the physicochemical factors, routes of exposure, biodistribution, molecular factors, genotoxicity and regulatory aspects. It is also involved in proposing reliable, healthy, and safe test protocols for nanomaterials in human and environmental risk assessment. Some nanoparticles such as copper is harmful to aquatic life, a small fraction of its nanoparticles can dissolve in water and produce toxic impacts on fish and other aquatic life. Copper nanoparticles are widely used as antimicrobial (antiviral, antibacterial, antifouling, antifungal), antibiotic treatment alternatives, nanocomposite coating, catalyst, lubricants, inks, for filtration of air and liquid. Fish are vulnerable to copper nanoparticles because it can induce gill injury and acute lethality. They are also emitted as particulates from smelters, metal foundries, and as pollutant from asphalt and rubber tires. Their long-term biological consequences on aquatic species are still unclear so it is pertinent to assess the toxicity of Cu nanoparticles and Cu salt in aquatic life. In view of these facts the following review article presents the toxicity, ways of exposure and effects of Cu nanoparticles on different organisms in vivo and vitro.

Fabrication of Al2O3‐Cu Nanocomposites Using Rotary Chemical Vapor Deposition and Spark Plasma Sintering

A two‐step rotary chemical vapor deposition technique was developed to uniformly mix Cu nanoparticles with the γAl2O3 powders, and then the as‐obtained powders were consolidated to Al2O3‐Cu nanocomposites by spark plasma sintering. In the RCVD process, the metal‐organic precursor of copper dipivaloylmethanate (Cu(DPM)2) reacted with O2 and then was reduced by H2 in order to erase the contamination of carbon. At 1473 K, the relative density of Al2O3‐Cu increased with increasing CCu and the maximum value was 97.7% at CCu = 5.2 mass%. The maximum fracture toughness of Al2O3‐Cu was 4.1 MPa m1/2 at CCu = 3.8 mass%, and 1 MPa m1/2 higher than that of monolithic Al2O3, validating the beneficial effects of Cu nanoparticles.

Impaired behavioural response to alarm substance in rainbow trout exposed to copper nanoparticles

To date, studies of the toxicity of engineered nanoparticles (NPs) in fish have not fully considered effects on olfactory-mediated behaviours, despite their ecological importance. In this study the effects of copper NPs (Cu NPs) on the anti-predator behavioural responses of juvenile rainbow trout (Oncorhynchus mykiss) to trout alarm substance was investigated. Individual fish were exposed for 12h to a control (no added Cu), 50μgl−1 of Cu as Cu NPs, or 50μgl−1 Cu as CuSO4, after which fish behaviours were analyzed in 10min periods before and after the addition of the alarm substance stimulus. The response of control fish to deionised water (negative control, no alarm substance stimulus) was also analyzed. The alarm substance elicited a behavioural response in the control fish characterized by an immediate freeze response and the slower resumption of swimming activity compared to negative controls exposed to the sham deionised water stimuli. In fish exposed to Cu NPs, the behavioural response to alarm substance was eliminated, with no significant difference in behaviours compared to negative controls. In comparison, exposure to 50μgl−1 Cu as CuSO4 decreased, but did not eliminate the response of fish to alarm substance, which indicated a significantly greater effect of Cu NPs on olfactory mediated behaviours than of the equivalent concentration of Cu as CuSO4. Measurement of total Cu concentrations in the tissues of fish demonstrated no significant accumulation of Cu from any treatment in gill, liver or brain, confirming the effects of Cu NPs, and to a lesser extent CuSO4, on behavioural responses were mostly associated with the interaction of the materials with the external surfaces of the fish. Scanning electron microscopy revealed that Cu as CuSO4 caused a pronounced depletion of ciliated sensory and non-sensory cells in the olfactory rosette surrounding the midline raphe, whereas Cu NPs had no impact on the structure of the rosette. However, exposure to Cu NPs caused a significant increase in the ratio of oxidized to reduced glutathione in brains of fish, indicating some systemic oxidative stress that was not observed in either controls or fish exposed to CuSO4. Overall, the study showed that the olfactory mediated behaviours of fish were potentially more sensitive to Cu NPs than CuSO4 and NPs elicited effects via a mechanism that is distinct from that of the metal salt.

An investigation of melting/freezing characteristics of nanoparticle-enhanced phase change materials

The aim of this study is to investigate the melting/freezing characteristics of paraffin by adding Cu nanoparticles. Cu/paraffin composite phase change materials (PCMs) were prepared by a two-step method. The effects of Cu nanoparticles on the thermal conductivity and the phase change heat transfer of PCMs were investigated by the Hot Disk thermal constants analyzer and infrared monitoring methods, respectively. The maximum thermal conductivity enhancements up to 14.2% in solid state and 18.1% in liquid state are observed at the 2 wt% Cu/paraffin. The photographs of infrared monitoring suggest that the melting and freezing rates of Cu/paraffin are enhanced. For 1 wt% Cu/paraffin, the melting and freezing times can be saved by about 33.3 and 31.6%, respectively. The results provide that adding nanoparticles is an efficient way to enhance the phase change heat transfer of PCMs.