Nanostructured Copper Research Articles

Low temperature growth of two-dimensional (2D) Cu/Cu2O nanosheets under ice/water mixing environment

Chemical vapor deposition (CVD) is considered as the most promising route towards low-cost and scalable growth of 2D nanomaterials. Nevertheless, low melting point substrate is not suitable for the high growth temperature (more than 773 K) requirement of CVD route, which limits its wide applications in electronic and catalysis fields. Under ice/water mixing environment (273 K–278 K) we have developed a low temperature growth of 2D Cu/Cu 2 O nanosheets, which demonstrate excellent oxygen reduction reaction (ORR) activity (onset potential: 0.987 V, halfwave potential: 0.921 V) under 273 K–278 K low temperature. Experimental and first-principles calculated results demonstrated that oriented attachment of copper nanostructures played an important role for the low temperature growth of 2D copper nanosheets, and abundant active Cu 2 O stepped atoms on 2D copper nanosheets resulted in excellent low temperature ORR activity. The unique ice/water mixing environment will pave a new road for low temperature growth of high quality 2D nanomaterials.

Life Span of Slippery Lubricant Infused Surfaces.

Since their discovery a decade ago, slippery liquid infused porous surfaces (SLIPSs) or lubricant infused surfaces (LISs) have been demonstrated time and again to have immense potential for a plethora of applications. Of these, one of the most promising is enhancing the energy efficiency of both thermoelectric and organic Rankine cycle power generation via enhanced vapor condensation. However, utilization of SLIPSs in the energy sector remains limited due to the poor understanding of their life span. Here, we use controlled conditions to conduct multimonth steam and ethanol condensation tests on ultrascalable nanostructured copper oxide structured surfaces impregnated with mineral and fluorinated lubricants having differing viscosities (9.7 mPa·s < μ < 5216 mPa·s) and chemical structures. Our study demonstrates that SLIPSs lose their hydrophobicity during steam condensation after 1 month due to condensate cloaking. However, these same SLIPSs maintain nonwetting after 5 months of ethanol condensation due to the absence of cloaking. Surfaces impregnated with higher viscosity oil (5216 mPa·s) increase the life span to more than 8 months of continuous ethanol condensation. Vapor shear tests revealed that SLIPSs do not undergo oil depletion during exposure to 10 m/s gas flows, critical to condenser implementation where single-phase superheated vapor impingement is prevalent. Furthermore, higher viscosity SLIPSs are shown to maintain good stability after exposure to 200 °C air. A subset of the durable SLIPSs did not show change in slipperiness after submerging in stagnant water and ethanol for up to 2 weeks, critical to condenser implementation where single-phase condensate immersion is prevalent. Our work not only demonstrates design methods and longevity statistics for slippery nanoengineered surfaces undergoing long-term dropwise condensation of steam and ethanol but also develops the fundamental design guidelines for creating durable slippery liquid infused surfaces.

Stable superhydrophobic and conductive surface: Fabrication of interstitial coral-like copper nanostructure by self-assembly and spray deposition

Water permeation is an important issue in both fundamental research and industrial applications. In this work, stable superhydrophobic copper surfaces were obtained by self-assembly and spray deposition on cotton fabrics. Scanning electron microscopy revealed that micro/nano dual-scale coral-like structures were established by the stacking of copper nanoparticles, thus forming a stable Cassie model for superhydrophobic feathers. The water contact angle of the surface was 161°, while the slide angle was as low as 3°. Chemical bonds were formed between substructures and copper nanoparticles by molecular grafting, which improved its mechanical stability, since the surface was verified to maintain a large contact angle after long-distance abrasion and folding. Compared with the superhydrophilic copper surface, the superhydrophobic coating showed better corrosion resistance in 3.5 wt% NaCl solution and artificial sweat. Combined with the inherent conductivity of copper, fabrics have potential applications in the new generation of advanced textiles.

Studies on Copper Nanometric-Film Deposited by an In-House Developed DC Magnetron Sputtering System

Copper nanofilms are extensively used in the field of material science research. Nanoparticles and nanostructures of copper have various utilities in the field of photocatalytic and sensor applications. The transition metal nanoparticles and nanostructures supply plenty free electrons which drastically enhances the optical and electrical properties compared to bulk material. Here, copper thin films have been deposited on glass slides and silicon substrates using an indigenously developed DC magnetron sputtering system. These depositions have been carried out at three different time spans keeping the magnetron discharge current, working vacuum and target to substrate distance unaltered. The objective of this work is to study the crystalline structure and measure the thickness of the copper nanofilm deposited at three different times. The synthesized films were characterized by using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Secondary Ion Mass Spectrometer (SIMS). Characteristic peaks of copper (111) along with Cu2O (110), (220) and (111) were obtained from the XRD pattern. The average grain size of the deposited films has been calculated using Debye-Scherrer equation. The film thickness ranging from 80-160 nm for various time spans were measured from depth profile analysis using SIMS data.

Influence of Particle Size and Shapes on the Antifungal Activities of Greener Nanostructured Copper against Penicillium italicum

Pathogenic microorganisms cause diseases that play a limiting role in food production. The growth of blue mold rot on citrus fruits caused by Penicillium italicum poses postharvest economic loss due to food decay. The control of P. italicum using toxic synthetic fungicide raises serious concerns about food safety and quality. There is a need to develop safe fungi management techniques to prevent economic loss in the agro-industry. Copper nanoparticles (CuNPs) are typically prepared at elevated temperatures (200 °C) using toxic surfactants such as cetyltrimethylammonium bromide (CTAB) and harsh organic solvents. We hereby report, for the first time, a novel greener and eco-friendly one-pot aqueous method for synthesizing copper nanospheres (CuNS) and well-defined copper nanocubes (CuNCs) with controlled shape and size using copper(II) sulfate (CuSO4) precursor and water-soluble quercetin diphosphate (QDP) as a bio-reducing and capping agent at room temperature. The CuNPs were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD). CuNCs with average edge lengths of 150–250 and 80–180 nm were designed using QDP and CuSO4 in the ratio of 3:1, respectively. The metrics of sustainability obtained include atom economy (73.56%), molar efficiency (0.9019), and environmental factor (3.429). The antifungal activity of CuNCs and CuNSs was tested against P. italicum using the Kirby–Bauer method. This study demonstrated the comparative effect of CuNCs and CuNSs on the growth of P. italicum spores in a dose-dependent manner. The results indicated that CuNCs and CuNSs showed antifungal activity against the growth of P. italicum, with the minimum inhibitory concentration (MIC) of 100 and 200 μg/mL, respectively. At a constant particle size, it was evident that CuNCs showed significant inhibitory activity of P. italicum at a low-dose treatment (100 μg/mL) in comparison to CuNS. The particle size and shape effect of CuNCs played a vital role in its antifungal activity. QDP-mediated synthesis of CuNC and CuNS could serve as a potent biocide for the natural remediation of citrus-based fungal diseases.

A Basic Research for Conquest Drawbacks and Further Improvement of Properties of Heterogeneous–Nano Structured Copper Alloys

A Basic Research for Conquest Drawbacks and Further Improvement of Properties of Heterogeneous–Nano Structured Copper Alloys

Influence of surface roughness and Wettability of novel surface on nucleate boiling performance in deionised water at atmospheric pressure

Pool boiling is one of the very suitable techniques for an efficient thermal management system dealing with two-phases. The present work deals with the experimental exploration of critical heat flux for safety concern and heat transfer coefficient related to the performance point of view in nucleate boiling regime of pool boiling system. The copper substrate was coated with porous copper nanoparticles by sputtering technique to the thicknesses of 250 nm, 500 nm, and 750 nm. The surface characteristics of the copper nanocoated surfaces have been analysed as a result of wettability, surface roughness, and micro-structure. The contact angle goniometer, stylus profilometer, XRD, and SEM have been employed to analyze the surface structure. The maximum augmentation of critical heat flux was 59% for the thickness of 750 nm as compared to plain copper substrate. A 99% increase in the heat transfer coefficient was achieved for 750 nm thickness surface in comparison with the plain copper surface. The tremendous augmentation in critical heat flux and heat transfer coefficient was achieved due to wetting and rewetting properties of the deionized water on the copper nanocoated surfaces. The capillary action on the copper nanostructure improves the fluid supply to the test surface and removes the heat at low wall superheat than the plain copper surface. The average roughness of the copper nanocoated surface augments the heat transfer area which tends to enhance the performance factor significantly.

Hierarchical copper nanostructures synthesized on microparticles for improved photothermal conversion in photonic sintering of copper-based printed electrodes

Photonic sintering of Cu-particle-based printed patterns using intense pulsed light (IPL) is a promising route to the large-scale fabrication of printed electronics for commercial applications.

Mannich-mediated synthesis of a recyclable magnetic kraft lignin-coated copper nanostructure as an efficient catalyst for treatment of environmental contaminants in aqueous media

Recently, the fabrication of heterogeneous catalysts using biopolymers has been considered due to some advantages such as biodegradability, easy handling, high efficiency and so on. In this work, 5-amino-1H-tetrazole modified kraft lignin/Fe3O4 supported highly catalytic active copper complex (Fe3O4@LigA/Cu) has been synthesized as a novel catalyst. The support was prepared by the Mannich reaction of 5-amino-1H-tetrazole and kraft lignin. The prepared catalyst was characterized by different techniques including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectrometry (EDX), elemental mapping, Brunauer-Emmett-Teller (BET) and vibrating sample magnetometry (VSM). The Fe3O4@LigA/Cu catalyst was used in the catalytic reduction of organic pollutants such as 4-nitrophenol (4-NP), methylene blue (MB), and congo red (CR) using sodium borohydride (NaBH4) as the reducing agent and the catalytic efficiency was studied by UV–visible spectroscopy. Fe3O4@LigA/Cu catalyst showed high yield (˃ 99%) in the reduction of 4-NP in four min. Moreover, Fe3O4@LigA/Cu catalyst showed good recyclability and reusability. This work provides a simple method for the preparation of lignin based catalysts with high catalytic activity and easy recovery to degrade organic pollutants from aqueous solution.

Three-Layer PdO/CuWO4/CuO System for Hydrogen Gas Sensing with Reduced Humidity Interference.

The growing hydrogen industry is stimulating an ongoing search for new materials not only for hydrogen production or storage but also for hydrogen sensing. These materials have to be sensitive to hydrogen, but additionally, their synthesis should be compatible with the microcircuit industry to enable seamless integration into various devices. In addition, the interference of air humidity remains an issue for hydrogen sensing materials. We approach these challenges using conventional reactive sputter deposition. Using three consequential processes, we synthesized multilayer structures. A basic two-layer system composed of a base layer of cupric oxide (CuO) overlayered with a nanostructured copper tungstate (CuWO4) exhibits higher sensitivity than individual materials. This is explained by the formation of microscopic heterojunctions. The addition of a third layer of palladium oxide (PdO) in forms of thin film and particles resulted in a reduction in humidity interference. As a result, a sensing three-layer system working at 150 °C with an equalized response in dry/humid air was developed.

Growth direction and exposed facets of Cu/Cu2O nanostructures affect product selectivity in CO2 electroreduction

The electrochemical reduction of CO2 to fuels and value-added chemicals on metallic copper is an attractive strategy for valorizing CO2 emissions. However, favoring the CO2 reduction over hydrogen evolution and exclusive control of selectivity towards C1 or C2+ products by restructuring the copper surface is a major challenge. Herein, we exploit the differential orientation of the exposed facets in copper nanostructures that can tune the product selectivity in CO2 electroreduction. The Cu nanostructure with predominant {111} orientation produce C1 products only upon CO2 electroreduction at an applied potential of −1.3 V vs. reversible hydrogen electrodes (RHE), with 66.57% Faradaic efficiency (FE) for methane. Whereas the vertically grown copper nanostructures that are oriented in {110} direction have higher dislocation density and show greater CO2 electroreduction activity (>95%) at the same applied potential, with FE towards ethylene 24.39% and that of oxygenates 41.31%. FIA-DEMS analysis provided experimental evidence of selectivity of methane over methanol at higher overpotentials indicating the mechanism of methane formation occurs via *COH intermediate. The ethylene formation at a potential −1.0 V vs. RHE or more negative to it suggests a common intermediate for methane and ethylene on the vertically grown copper nanostructures. This work advances the understanding between the product selectivity and the surface structure of the copper nanostructures in electrochemical CO2 reduction.

Effect of Copper and Titanium-Exchanged Montmorillonite Nanostructures on the Packaging Performance of Chitosan/Poly-Vinyl-Alcohol-Based Active Packaging Nanocomposite Films

In this study, CuMt and TiMt montmorillonites were produced via an ion-exchange process with Cu+ and Ti4+ ions. These nanostructured materials were characterized with X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) measurements and added as nanoreinforcements and active agents in chitosan (CS)/poly-vinyl-alcohol (PVOH)-based packaging films. The developed films were characterized by XRD and FTIR measurements. The antimicrobial, tensile, and oxygen/water-barrier measurements for the evaluation of the packaging performance were carried out to the obtained CS/PVOH/CuMt and CS/PVOH/TiMt films. The results of this study indicated that CS/PVOH/CuMt film is a stronger intercalated nanocomposite structure compared to the CS/PVOH/TiMt film. This fact reflected higher tensile strength and water/oxygen-barrier properties. The antibacterial activity of these films was tested against four food pathogenic bacteria: Escherichia coli, Staphylococcus aureus, Salmonella enterica and Listeria monocytogenes. Results showed that in most cases, the antibacterial activity was generated by the CuMt and TiMt nanostructures. Thus, both CS/PVOH/CuMt and CS/PVOH/TiMt films are nanocomposite candidates with very good perspectives for future applications on food edible active packaging.

Hydrogen evolution assisted cyclic electroplating for lateral copper growth in wearable electronics

• Hydrogen evolution assisted (HEA) electroplating was applied for copper growth. • Cyclic electroplating method was used to control the copper nanostructure. • Scan rate of 100 mV/s has been identified for fast growth of copper. Recent progress in hydrogen evolution assisted (HEA) electroplating has shown promises for fast lateral growth of copper on various rigid and flexible substrates. In this method, concurrent to the copper reduction, hydrogen bubbles are generated at the cathode resulting in a porous copper layer with a growth rate a few orders of magnitude faster than the standard electroplating method. However, the application of constant voltage does not allow bubbles to leave the surface resulting in non-uniform copper growth and unpredictable nanostructures. To allow the hydrogen bubbles to leave the surface, we have applied a cyclic electroplating method in a voltage range that the electroplating alternates between the HEA and non-HEA modes. The effect of the voltage range and the voltage scan rate on the lateral growth of copper and the quality of the copper layer were investigated on a patterned copper track on a standard printed circuit board (PCB). The fastest growth rate of 55 µm/s was obtained for a voltage range between −1.5 V and −0.8 V with a scan rate of 100 mV/s. The scanning electron microscopy (SEM) images of different samples revealed that the scan rate affects the nanostructure of the grown copper layer. The feasibility of applying the HEA cyclic electroplating method for developing wearable electronics was demonstrated by growing copper on a piece of fabric to make contact with the pins of a light emitting diode.

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649.

Increasing heat dissipation requirements of small and miniature devices demands advanced cooling methods, such as application of immersion cooling via boiling heat transfer. In this study, functionalized copper surfaces for enhanced heat transfer are developed and evaluated. Samples are functionalized using a chemical oxidation treatment with subsequent hydrophobization of selected surfaces with a fluorinated silane. Pool boiling tests with water, water/1-butanol mixture with self-rewetting properties and a novel dielectric fluid with low GWP (Novec™ 649) are conducted to evaluate the boiling performance of individual surfaces. The results show that hydrophobized functionalized surfaces covered by microcavities with diameters between 40 nm and 2 µm exhibit increased heat transfer coefficient (HTC; enhancements up to 120%) and critical heat flux (CHF; enhancements up to 64%) values in comparison with the untreated reference surface, complemented by favorable fabrication repeatability. Positive surface stability is observed in contact with water, while both the self-rewetting fluids and Novec™ 649 gradually degrade the boiling performance and in some cases also the surface itself. The use of water/1-butanol mixtures in particular results in surface chemistry and morphology changes, as observed using SEM imaging and Raman spectroscopy. This seems to be neglected in the available literature and should be focused on in further studies.

Nanostructured Mesoporous Zinc-Incorporated Copper Oxide (NMZI-CuO): An Efficient and Reusable Nanocatalyst for the Oxidant-Free Synthesis of Quinoxalines through a Tandem Oxidation Process

A nanostructured mesoporous zinc-incorporated copper oxide with different Cu/Zn molar ratios was prepared through a facile hydrothermal template-free route. Textural properties of prepared materials were studied with various techniques such as TEM, BET, XRD, FTIR, and XPS. The prepared mesoporous zinc-incorporated copper oxide was then successfully applied as a heterogeneous catalyst for the synthesis of quinoxaline derivatives from 1,2-diamines and α -hydroxy ketones through a tandem oxidation process (TOP) without any oxidant. Using this method all desired products were obtained with good to excellent yields in relatively short times under solvent-free conditions. The applied catalyst was simply isolated and reused several times without any detectable loss of catalytic activity.

Enhancement the larvicidal activity of nanostructure copper oxide against Culex pipiens mosquito by yttrium replacement based on crystallite size reduction and topographic surface nature

The current work aims to improve the metal oxide characteristics for mosquito control. Un-doped and Y-doped CuO have been synthesized by simple chemical route. Structural, composition, and morphological properties were characterized by XRD, Raman spectra, EDX, SEM, and TEM techniques. The obtained results revealed that CuO was strongly affected by Y3+ support, in which the crystallite size decreased, and the surface area increased. Larvicidal performance was assessed against Culex pipiens suggesting that the nanocomposite CuO/Y of higher efficiency (LC50 = 7.67 mg /l, R2 = 0.977) compared with pure CuO. Light microscopy and SEM images exhibited larvae malformations owing to using the fabricated nanomaterials.

Fabrication of one-dimensional Bi2WO6/CuBi2O4 heterojunction nanofiber and its photocatalytic degradation property

In this paper, electrospinning method was used to prepare a one-dimensional nanostructured copper bismuthate-bismuth tungstate photocatalyst. The bismuth tungstate nanosheet structure was prepared by solvothermal method, and the copper bismuthate-bismuth tungstate precursor nanofibers were prepared by electrospinning using the doping method. The one-dimensional copper bismuthate-bismuth tungstate nanofiber structure was prepared by the high-temperature decomposition. The results show that the diameter of the bismuth tungstate and copper bismuthate nanofibers is about 280 nm, with continuous and regular fiber morphology. The fibers are composed of semiconductor nano-heterojunction and show good photocatalytic degradation efficiency for tetracycline hydrochloride. After 120 min of illumination, the degradation efficiency is greater than 90%, and it can be recycled and reused. The photocatalytic mechanism analysis showed that the energy band structure of the copper bismuthate-bismuth tungstate nano-semiconductor fiber was a Z-type heterojunction, and the free radical capture experiment showed that h + and •O 2− were main groups involved in oxidation reaction. The structure of high specific surface area of the nanofibers will improve the separation of photo-generated electrons and holes, and the experiment results show it has good performance of photocatalytic. • Electrospinning was used to prepare a one-dimensional nanostructured copper bismuthate-bismuth tungstate photocatalyst. • The fibers are composed of nano-heterojunction and show good photocatalytic performance for tetracycline hydrochloride. • High specific surface area of fibers improves the separation of electrons and holes to show good photocatalytic performance.

Enhancement of Activity of Copper Sites Toward Electroreduction of Carbon Dioxide through Hierarchical Deposition of Metal Oxide Cocatalysts

Of particular interest to the preparation of advanced catalytic materials is efficient utilization of nanosized materials with well-defined composition, structure and thickness that exhibit desirable electrocatalytic properties. There has been growing interest in the electrochemical conversion of carbon dioxide (a potent greenhouse gas and a contributor to global climate change) to useful carbon-based fuels or chemicals. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large over-potentials. It is often postulated that, during electroreduction, the rate limiting step is the protonation of the adsorbed CO product to form the CHO adsorbate. In this respect, the proton availability and its mobility at the electrochemical interface has to be addressed. On the other hand, competition between such parallel processes as hydrogen evolution and carbon dioxide reduction has also to be considered.We explore here the ability of polynuclear transition metal oxide based systems to function as cocatalysts and to stabilize and activate metal nanocenters. Here certain nanostructured metal oxides of zirconium, titanium, molybdenum or tungsten have been demonstrated to influence supported catalytic metal sites in ways other than simple dispersion over electrode area. Evidence is presented that the support can modify activity (presumably electronic nature) of catalytic metal nanoparticles (e.g. Cu, Ru), thus affecting their chemisorptive and catalytic properties during CO2-reduction. Metal oxide (WO3, MoO3, TiO2) nanostructures can generate highly reactive –OH groups at electrocatalytic interface.Evidence is presented that the support can modify activity (presumably electronic nature) of catalytic metal nanoparticles (e.g. Cu, Pd), thus affecting their chemisorptive properties. Metal oxide (ZrO2, WO3) nanospecies can generate –OH groups at electrocatalytic interface. Our electrocatalytic results with copper nanostructures over-coated with ZrO2 or WO3 nanostructures imply the systems’ improved selectivity toward CO2-reduction relative to the competitive hydrogen evolution as well as the lower tendency of copper sites to undergo poisoning.

Enhancement of Activity of Copper Sites Toward Electroreduction of Carbon Dioxide through Hierarchical Deposition of Metal Oxide Cocatalysts

There has been growing interest in preparation of the advanced catalytic systems that efficiently utilize nanosized materials with well-defined composition, structure, thickness and desirable electrocatalytic properties. The ability of polynuclear inorganic metal oxo systems to support, stabilize and functionalize catalytic metal nanostructures is explored here. Certain nanostructured metal oxides, including oxides of zirconium and tungsten, have been demonstrated to influence catalytic metal centers in ways other than simple dispersion over electrode area. Evidence is presented that the support can modify activity (presumably electronic nature) of catalytic metal nanoparticles (e.g. Cu), thus affecting their chemisorptive and catalytic properties. Metal oxide (ZrO2, WO3) nanospecies can generate –OH groups at electrocatalytic interface. Our electrocatalytic results with copper nanostructures over-coated with ZrO2 or WO3 nanostructures imply the systems’ improved selectivity toward CO2-reduction relative to the competitive hydrogen evolution as well as the lower tendency of copper sites to undergo poisoning

Nanostructured Copper Surface Kills ESKAPE Pathogens and Viruses in Minutes.

In the search for a fast contact-killing antimicrobial surface to break the transmission pathway of lethal pathogens, nanostructured copper surfaces were found to exhibit the desired antimicrobial properties. Compared with plain copper, these nanostructured copper surfaces with Cu(OH)2 nano-sword or CuO nano-foam were found to completely eliminate pathogens at a fast rate, including clinically isolated drug resistant species. Additionally these nanostructured copper surfaces demonstrated potential antiviral properties when assessed against bacteriophages, as a viral surrogate, and murine hepatitis virus, a surrogate for SARS-CoV-2. The multiple modes of killing, physical killing and copper ion mediated killing contribute to the superior and fast kinetics of antimicrobial action against common microbes, and ESKAPE pathogens. Prototypes for air and water cleaning with current nanostructured copper surface have also been demonstrated.