Effect Of Cu Nanoparticles Research Articles

Size Effect of Cu Nanoparticles from Cu–Al Spinel Catalysts on Product Distribution via CO Hydrogenation

Size Effect of Cu Nanoparticles from Cu–Al Spinel Catalysts on Product Distribution via CO Hydrogenation

Photothermal oxidative dehydrogenation of propane to propylene over Cu/BN catalysts.

Oxidative dehydrogenation of propane (ODHP) is a reaction with significant practical significance. As for the industrial application of ODHP, it is challenging to achieve high activity and high propylene selectivity simultaneously. In this study, to overcome this obstacle, we designed a series of Cu/BN catalysts with unique morphologies for establishing a photothermal ODHP system with high efficiency and selectivity. Characterization and evaluation results revealed that Cu/BN-NS and Cu/BN-NF with enlarged specific surface areas exhibited higher catalytic activities. The localized surface plasmon resonance (LSPR) effect of Cu nanoparticles further enhanced the photothermal catalytic performances of Cu/BN catalysts under visible light irradiation. To the best of our knowledge, it is the first time to establish a BN-based photothermal ODHP catalytic system. This study is expected to pave pathways to realize high activity and propylene selectivity for the practical application of ODHP.

Glucose and UA sensing based on Cu nanoparticle decorated Nif/GO flexible electrode.

Anovel, green, and facile approach has been developed to construct an ultrasensitive flexible enzyme-less electrochemical sensor on the basis of chitosan and graphene oxide composites decorated with Cu nanoparticles supported on nickel foam (Nif/Cs/GO@Cu), in which GO functions as the intermediate between Nif and Cu nanoparticles. The Nif/Cs/GO@Cu sensing platform was successfully fabricated by thedrop casting method to load Cs/GO onto Nif followed by an additionally electrodeposition to support Cu nanoparticles on Nif/Cs/GO. Impressively, the Nif/Cs/GO@Cu exhibited much higher electrocatalytic activity for glucose and UA oxidation as compared to that of Nif or Nif@Cu. For glucose and UA at about 0.6V and 0.1V (vs. Ag/AgCl), linearity could be obtained in the concentrationranges 5µM-4mM and 5-345µM;the sensitivities were16 and 2.5 µA µM-1cm-2, and the detection limits 83nM and 0.3 µM, respectively. The improved performance ofthe composite electrode was ascribed to the synergistic effect of Cu nanoparticles, Nif and GO, in which GO provides high electron conductivity and large surface area to prevent the agglomeration of Cu nanoparticles; Cu nanoparticles and Nif offer abundant active sites towards analytes oxidation. Additionally, the method was applied to determine both analytes successfully in blood serum samples with excellent recovery and also opens up an attractive route to potential applications of theflexible nickel foam-based electrochemical sensor.

Size Effect of Cu Nanoparticles in Cu/g-C3N4 Composites on Properties for Highly Efficient Photocatalytic Reduction of CO2 to Methanol.

The main goal of this work is to develop cheap photocatalysts for the efficient photocatalytic reduction of CO2 to methanol with water. A series of composites of Cu/g-C3N4 were prepared via a solvothermal method. Copper nanoparticle (Cu NP) size in Cu/g-C3N4 can be easily controlled by adjusting the synthesis temperature. The Cu/g-C3N4 material with the proper size of Cu NP (CuCN-100) had the best photocatalytic property (675 μmol·g-1·h-1) in reducing the amount of CO2 to methanol at room temperature under normal pressure. The particle size of Cu NPs is the key factor to improve the catalytic activity and stability because of the improved transfer and separation of photogenerated charges with the small Cu NPs. Although the sample with large Cu NPs (CuCN-200) initially gave a better activity than that of CuCN-100 due to the formation of double heterojunction, its activity was thoroughly lost after two runs resulting from the continuous photocorrosion. This work provides a valuable insight for preparing efficient semiconductor-metal photocatalysts.

NH3 synthesis via visible-light-assisted thermocatalytic NO reduction by CO in the presence of H2O over Cu/CeO2

A photothermal catalytic system comprising Cu/CeO2 was applied to the reaction between NO, CO and H2O for the production of NH3 under visible-light irradiation. High NO conversion (94.4%) and NH3 selectivity (66.5%) were achieved over Cu/CeO2 in the presence of H2O at 210 °C. Visible light further improved the conversion of NO (97.7%) and selectivity for NH3 (69.1%). The quasi-situ EPR and in-situ DRIFTS results indicated that CO initially reacts with H2O to form an HCO3* intermediate, which then decomposes into CO2 and activated H*. Finally, NO reacts with activated H* to produce NH3. The localized surface plasmon resonance effect of Cu nanoparticles induced by visible light promotes the decomposition of HCO3* to CO2 and H*, while regenerating oxygen vacancies (OVs, H2O activation sites) at the CeO2 sites, resulting in enhanced NH3 production. This study offers a convenient approach for NH3 production under mild conditions.

In Operando Photoswitching of Cu Oxidation States in Cu-Based Plasmonic Heterogeneous Photocatalysis for Efficient H2 Evolution.

Metal nanoparticles (NP) supported on TiO2 are known to be efficient photocatalysts for solar-to-chemical energy conversion. While TiO2 decorated with copper NPs has the potential to become an attractive system, the poor oxidative stability of Cu severely limits its applicability. In this work, we demonstrate that, when Cu NPs supported on TiO2 nanobelts (NBs) are engaged in the photocatalytic generation of H2 from water under light illumination, Cu is not only oxidized in CuO but also dissolved under the form of Cu+/Cu2+ ions, leading to a continuous reconstruction of nanoparticles via Ostwald ripening. By nanoencapsulating the CuOx (Cu/CuO/Cu2O) NPs by a few layers of carbon supported on TiO2 (TC@C), Ostwald ripening can be suppressed. Simultaneously, the resulting CuOx@C NPs are photoreduced under light illumination to generate Cu@C NPs. This photoswitching strategy allows the preparation of a Cu plasmonic photocatalyst with enhanced activity for H2 production. Remarkably, the photocatalyst is even active when illuminated with visible light, indicating a clear plasmonic enhancement of photocatalytic activity from the surface plasmonic resonance (SPR) effect of Cu NPs. Three-dimensional electromagnetic wave-frequency domain (3D-EWFD) simulations were conducted to confirm the SPR enhancement. This advance bodes for the development of scalable multifunctional Cu-based plasmonic photocatalysts for solar energy transfer.

Surface hydrophobicity-hydrophilicity switching induced interface heat and water transfer enhancement for high-efficiency solar steam generation

Beyond photothermal conversion, the surface wettability of light-absorbing materials should be also determinative to the efficiency of solar-driven interfacial steam generation (SISG). Herein, by modifying hydrophobic Cu nanoparticles (NPs) with a hydrophilic carbon (C) shell, hydrophilic Cu@C core–shell NPs were successfully fabricated and used for constructing evaporation films for SISG. In comparison to the film constructed with Cu NPs, the evaporation films constructed with Cu@C core–shell NPs exhibit much increased SISG efficiency, reaching 94.6% as high. Except for the localized surface plasmon resonance (LSPR) effect of Cu NPs ensuring the excellent photothermal conversion, it is experimentally and theoretically revealed that the surface wettability switching from hydrophobicity to hydrophilicity, as induced by C coating, is beneficial to heat transfer at the solid/liquid interface and water transport at the evaporative surface, thus improving the thermal-evaporation conversion performance for efficient SISG. However, the further thickened C shells would weaken the LSPR effect and hinder the interface heat and water transfer, leading to the decreased photothermal and thermal-evaporation conversion efficiencies, and thus the lowered SISG performances. This demonstration gives an alternative and promising access to the rational design of photothermal materials featured with switchable surface wettability ensuring interface heat and water transfer enhancement for efficient SISG.

Designed synthesis of nanostructured ZrO2 as active support for glycerol valorization reaction

Designed synthesis of nanostructured ZrO 2 as support for glycerol valorization reaction was investigated. The nanocasting route was used to obtain the ZrO 2 support possessing well-dispersed Cu and Zn nanoparticles. The solids were fully characterized by High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Electron paramagnetic resonance (EPR), N 2 -physisorption isotherms, Temperature-programmed desorption of ammonia (NH 3 -TPD), Scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS) and Fourier transform infrared (FTIR) spectroscopy measurements. The resultant CuZn/ZrO 2 catalyst presented here was distinguished by its unique mesostructured features and defective sites formation. The promotional effect of Cu nanoparticles on the activity illustrated that the formation of active acid sites of medium to strong strength can be modulated by adding a second metal to the catalyst. All these properties provided active solids for acetalization of glycerol with aldehydes and ketones due to the interaction between the active centers and the nanostructured support. Density functional theory (DFT) calculation showed the most favorable mechanistic route of low energy for biofuel additives production.

Copper Nanoparticles Induce Apoptosis and Oxidative Stress in SW480 Human Colon Cancer Cell Line.

Cu nanoparticles (CuNPs) have various applications in biomedicine, owing to their unique properties. As the effect of CuNPs on the induction of oxidative stress and apoptosis in the human colorectal cancer cell line SW480 has not yet been studied, we investigated the toxicity and mechanism of action of these NPs in SW480 cells. MTT assay was performed to assess the effect of the particles on the viability of SW480 cells. The levels of oxidative stress were assessed after 24h of treatment with CuNPs by evaluating the Reactive Oxygen Specious (ROS) production. The antioxidant enzyme activity was assessed using a colorimetric method. To investigate the effect of NPs on cellular apoptosis, Hoechst33258 staining was performed, and the expression of Bax, Bcl-2, and p53 was evaluated by qRT-PCR. The MTT assay results showed that CuNPs inhibited the viability of SW480 cells. Moreover, the increase in ROS production at all three concentrations (31, 68, and 100μg/ml) was significant. It has been observed that CuNPs lead to increased expression of Bax and p53, and decreased expression of Bcl-2. Hoechst staining was performed to confirm apoptosis. In conclusion, the induction of apoptosis demonstrated the anticancer potential of the CuNPs.

Optimized hot electron injection from Cu nanoparticles to S-doped C3N4 by the formed S-Cu bonds for an enhanced photocatalytic performance.

Low-cost and high-abundance Cu nanostructures are potential near-infrared (NIR) surface plasmonic resonance (SPR) photosensitizers for carbon nitride (C3N4) photocatalysts, but their low activity and stability need to be improved. In this article, doping S into C3N4 (S-C3N4) creates anchoring sites for photo-deposited Cu nanoparticles (NPs), and the spontaneous construction of S-Cu bonds is realized between S-C3N4 and Cu NPs. The optimal hydrogen evolution rate of 1.64 mmol g-1 h-1 is obtained for S-C3N4-Cu, which is 5.5, 4.6 and 1.7 times that of pure C3N4, S-C3N4 and S-C3N4-Cu, respectively. With further loading of a Pt co-catalyst to confirm the role of Cu NPs and improve the photocatalytic activity of the SCN-Cu, the photocatalytic rate can reach up to 14.34 mmol g-1 h-1. Due to the NIR SPR effect of Cu NPs, the apparent quantum efficiency (AQE) of S-C3N4-Cu at 600 and 765 nm is 2.02% and 0.47%, respectively. The enhanced photocatalytic performance of S-C3N4-Cu compared with C3N4-Cu is mainly due to the introduced S-Cu bonds that improve the injection rate of hot electrons. This solution provides a simple and efficient interface optimization strategy for the construction of efficient NIR-driven photocatalysts.

Effect of Cu Nanoparticles on the Properties of PP-g-PHMG/PE Monofilament and Its Antifouling Application

The modified polyethylene monofilament was prepared by melt blending and spinning using polyethylene (PE), polypropylene-grafted poly(hexamethylene guanidine) (PP-g-PHMG), and Cu nanoparticles (CuNPs). The effect of CuNP content on the structure, mechanical properties, and antimicrobial properties of the monofilaments was studied. In addition, the antifouling property of fishing nets using the modified polyethylene monofilaments was evaluated. The results showed that CuNPs were dispersed homogeneously in the monofilament matrix as microaggregates. The initial increase in the tensile strength of monofilament was attributed to the mechanical restraint, whereas a decrease in the tensile properties at 1.0 wt% CuNP content was due to the predominant effect of a decrease in the total crystallinity. A bacteriostatic test showed that the monofilament had an obvious inhibitory effect on Staphylococcus aureus. Furthermore, coupon test results showed that PP-g-PHMG/PE/CuNP nanocomposite netting had lower weight gain than PP-g-PHMG/PE netting (23.6% reduction) because of the combined antibacterial effect of both PHMG and CuNP. Therefore, PP-g-PHMG/PE/CuNP monofilament has the potential to produce green and efficient antifouling fishing nets.

Effect of Cu nanoparticles on the tribological performance of polydopamine + polytetrafluoroethylene coatings in oil-lubricated condition

The effect of Cu nanoparticles (NPs) on the tribological performance of the thick polydopamine (PDA) + polytetrafluoroethylene (PTFE) coatings in DTE-32 Mobil lubricated condition was investigated. PDA + PTFE + Cu NP coatings with 45 µm thickness were spray-coated with 0.12, 0.25, and 0.50 wt% of Cu NPs in an aqueous PDA + PTFE solution, respectively. The mechanical properties were studied by PeakForce quantitative nanomechanical (PFQNM) characterization and nanoindentation. The Young's modulus increased, and the coefficient of friction (COF) reduced with the addition of Cu NPs compared to PDA + PTFE coating. The PDA + PTFE + 0.25 wt% Cu and PDA + PTFE + 0.50 wt% Cu coatings increased the durability by 52% and 33%, respectively, compared to the coating without Cu NPs. The better tribological performance of the nanocomposite coatings is contributed by the better mechanical properties, better adherence, and enhanced cross-linking between the constituents of the nanocomposite coatings due to the presence of Cu NPs. The addition of 0.25 wt% Cu NPs in PDA + PTFE increased the thermal conductivity by 12%.

Enhancement of mechanical properties and conductivity in carbon nanotubes (CNTs)/Cu matrix composite by surface and intratube decoration of CNTs

Strength and ductility are often a paradox in carbon nanotubes (CNTs) reinforced Cu matrix composite, as well as strength and electrical conductivity. Interface and characteristics of CNTs are critical factors in determining the mechanical properties and conductivity of Cu matrix composites. In the present study, a novel tactic by surface and intratube decoration of CNTs is adopted to break the above mentioned dilemmas. By decorating the surface of CNTs with CuO nanoparticles and taking advantage of the good wettability between CuO and Cu matrix, uniform dispersion of CNTs is realized through ball milling. In the final composite, CuO nanoparticles on the surface of CNTs are reduced to Cu. High density interfacial dislocations and interfacial disordered areas are formed between Cu matrix and CNTs, thus forming a strong interfacial bonding. By decorating the inner walls of CNTs with Cu nanoparticles, the interfacial shear stress between Cu matrix and CNTs is improved due to the extrusion effect of Cu nanoparticles on the inner walls. Moreover, the Cu filled inside the tubes can also reduce the intra-tube resistivity of CNTs by increasing their conducting cross-section. Consequently, the Cu matrix composite with simultaneous improvement of strength (272 MPa), ductility (14.3%) and conductivity (93.6% IACS) is achieved in our present study. This tactic provides a new idea to deal with the strength-ductility and strength-conductivity dilemmas in CNTs reinforced metal matrix composites. • Surface and intratube decoration of CNTs is carried out in CNTs/Cu composite. • Uniform distribution and strong interface bonding obtained due to CuO on CNT surface. • Increased interfacial shear stress obtained due to pressure from Cu inside CNTs. • Decreased intra-tube resistivity obtained due to Cu inside CNTs. • Strength, ductility and conductivity increase simultaneously in CNT/Cu composite.

The distinct role of non-noble metal Cu NPs deposition in boosting the overall photocatalytic performance over a ternary Zn-based photocatalyst system

Metal nanoparticles (NPs) deposition is an effective strategy to enhance the photocatalytic performance. Here, we developed a non-noble Cu NPs deposition strategy to largely boost the overall photocatalytic performance of a ternary Zn-based composite photocatalyst (ZnTiO3/Zn2Ti3O8/ZnO, ZTO). The physicochemical properties of copper-deposited ZTO were extensively analyzed by a series of techniques such as XRD, BET, FT-IR, XPS, TEM, PL, and photoelectrochemical tests. And the free radical and light absorption properties of copper-deposited ZTO were examined by ESR and UV–vis DRS, respectively. The photocatalytic performance for hexavalent chromium reduction removal, dye decomposition, and water splitting for hydrogen production without noble metal cocatalyst were investigated. The results show that with suitable Cu content (3%~ 4.7%), the Cu-ZTO samples showed high activity for Cr(VI) reduction (3.2 times reduction rate of ZTO), dye decomposition(5.3 times degradation rate of ZTO), and hydrogen generation (19 times of the H2 production rate of ZTO). The synergistic effect between the plasma effect of Cu NPs and single Z-scheme mechanism over ternary ZTO results in a strong visible light absorption and fast separation of photogenerated electrons and holes. Thus, a superior photocatalytic performance was obtained over this novel Cu-ZTO photocatalyst system.

Synthesis of Copper and Silver Nanoparticles by Using Microwave-Assisted Ionic Liquid Crystal Method and Their Application for Nonenzymatic Hydrogen Peroxide Determination

The non-enzymatic copper (Cu) and silver (Ag)/ionic liquid crystal (ILC)/graphite paste nanocomposite electrodes were designed for the sensitive determination of hydrogen peroxide (H2O2). The microwave-assisted ILC (MAILC) method was applied for the synthesis of Cu or Ag nanoparticles by using the mixture of its corresponding acetate salt and ILC (1, 1′-dialkyl-4, 4′-bipyridinium bis (triflimide) s) for the first time. This route did not employ any additional template agent, surface capping and reducing agents, supporting materials, or also inert atmosphere. The process was fast, simple and high-yielding. ILC can act as the ordered reaction medium, microwave absorber and reducing and stabilizing agents. The synthesized Cu or Ag/ILC nanocomposite was mixed as binder with the appropriate amount of graphite for the fabrication of Cu or Ag/ILC/graphite paste nanocomposite electrode, without any further treatment. This type of ILC has great thermal stability due to the triflimide counter ions that preserves its structure even after microwave treatment. Excellent electrocatalytic effects toward H2O2 were observed for the Cu/ILC/graphite paste nanocomposite electrode compared to Ag/ILC/graphite paste nanocomposite electrode. The results showed the higher electrocatalytic effect of Cu nanoparticles with respect to Ag nanoparticles for the determination of H2O2. The Cu/ILC/graphite paste nanocomposite electrode achieved linear ranges of 4.0 µM to 0.4 mM and 0.4–10 mM with correlation coefficients of 0.9939 and 0.9974, respectively, for H2O2 determination.

Assessment of the biological effect of Cu nanoparticles impregnated in polyethylene medical devices combined with the effect of LED radiation of the red and violet spectra on the ability of microorganisms to form biofilms and on daily biofilms

For many years scientists around the world have been looking for an alternative to antibiotics due to rapidly growing level of resistance to them. LED light of various spectra and metal nanoparticles are considered as a promising alternative to antibiotics. In this work, we determined the complex effect of copper nanoparticles impregnated in high-pressure polyethylene and non-woven material with the effect of red and violet LED radiation on the ability of microorganisms to form biofilms and on already formed daily biofilms.

A Non-Enzymatic Sensor Based on Fc-CHIT/CNT@Cu Nanohybrids for Electrochemical Detection of Glucose.

Herein, a composite structure, consisting of Cu nanoparticles (NPs) deposited onto carbon nanotubes and modified with ferrocene-branched chitosan, was prepared in order to develop a nonenzymatic electrochemical glucose biosensor ferrocene-chitosan/carbon nanotube@ Cu (Fc-CHIT/CNT@Cu). The elemental composition of the carbon nanohybrids, morphology and structure were characterized by various techniques. Electrochemical impedance spectroscopy (EIS) was used to study the interfacial properties of the electrodes. Cyclic voltammetry (CV) and chronoamperometry methods in alkaline solution were used to determine glucose biosensing properties. The synergy effect of Cu NPs and Fc on current responses of the developed electrode resulted in good glucose sensitivity, including broad linear detection between 0.2 mM and 22 mM, a low detection limit of 13.52 μM and sensitivity of 1.256 μA mM−1cm−2. Moreover, the modified electrode possessed long-term stability and good selectivity in the presence of ascorbic acid, dopamine and uric acid. The results indicated that this inexpensive electrode had potential application for non-enzymatic electrochemical glucose detection.

Strategic design of Cu/TiO2-based photoanode and rGO-Fe3O4-based counter electrode for optimized plasmonic dye-sensitized solar cells

Abstract The current research work demonstrates the modification of both functional electrodes of a plasmonic dye-sensitized solar cell (PDSSC) to fabricate a low-cost and efficient solar device. The copper-doped titania (Cu/TiO2) nanocomposite and hybrid magnetite nanoparticles decorated reduce graphene oxide (rGO/Fe3O4) nanocomposite were produced by a facile single step wet synthesis approach by utilizing non-toxic and cost-efficacious precursors. The as-synthesized nanocomposites were comprehensively analyzed by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis and UV–Vis spectroscopic techniques to evidently confirm the formation of Cu/TiO2 and hybrid rGO/Fe3O4 nanocomposites successfully. The photovoltaic parameters of the PDSSCs were investigated by measuring J-V characteristics and IPCE spectra. The Cu/TiO2 nanocomposite based photoanode demonstrated power conversion efficiency (PCE) of 3.89% with platinum (Pt) and 2.20% with hybrid rGO/Fe3O4 counter electrodes (CEs) respectively in PDSSCs. The hybrid rGO/Fe3O4 CE based PDSSC approached to 57% of the efficiency of the traditional platinum electrode with Cu/TiO2 and 70% with that of pristine TiO2 based photoanodes. The reasonable enhancement in efficiency might be ascribed to uniform dispersion of catalytic Fe3O4 nanoparticles on the surface of rGO nanosheets and due to plasmonic effect of Cu nanoparticles. The results suggested that the synergistic combination of modified functional electrodes in plasmonic DSSCs exhibited a reasonable efficiency and thus could prove to be as an effective substituent of traditional and expensive Pt.

The effect of Cu nanoparticles on the characteristics of vapor–liquid interface of argon at various saturated temperatures by molecular dynamic simulation

In this study, the effect of copper nanoparticles on the interface properties of liquid–vapor argon is investigated by molecular dynamics simulation. Stoddard Ford potential function has been utilized to estimate the interactions of argon–argon and argon–copper particles. Simulation is done in the nanoscale computational domain to phase change of vapor to liquid at different saturated temperatures. Density values and surface tension for different cutoff radii are obtained. It is demonstrated that in the $$r_{\text{c}} = 4\sigma$$ calculated values are acceptable. Simulation results show that nanoparticles change the interface properties of liquid–vapor argon. With addition of nanoparticles, liquid density decreases and vapor density increases. Nanoparticles displace density distribution and cause fluctuations in the density profile. Also, surface tension increases with increase in nanoparticle concentration.

A Novel In Situ Synthesis of Cu/Cu2O/CuO/Sulfonated Polystyrene Heterojunction Photocatalyst with Enhanced Photodegradation Activity

The heavy metal copper ion from the industrial wastewater were recycled by sulfonated polystyrene, which were converted to Cu/Cu2O/CuO/SPS heterojunction photocatalyst through the hydrothermal synthesis process. The hydrothermal synthesis temperature was investigated on the surface morphology, crystal structure and photocatalytic performance of the as-prepared samples. The samples were characterized by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and UV–Vis diffuse reflectance spectra (UV–Vis DRS). The photocatalytic activities of the samples were investigated by the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that Cu, Cu2O and CuO nanoparticles are uniformly distributed on the surface of sulfonated polystyrene microsphere. Meanwhile, the enhanced visible light absorption is originated from the surface plasmon resonance effect of Cu nanoparticles (CuNPs). The surface morphology and crystal structure of the sample were changed as the hydrothermal synthesis temperature rising. The sample by hydrothermal synthesis at 80 °C exhibited the preferable photocatalytic activity attributed the high dispersion of Cu, Cu2O and CuO nanoparticles and the formation of heterojunction between Cu2O and CuO.