Nanostructured Copper Research Articles

N-Graphene Sheet Stacks/Cu Electrocatalyst for CO2 Reduction to Ethylene

Renewable energy resources (wind, solar) are unpredictable, so it is wise to store the electricity they generate in an energy carrier X. Various PtX (power to useful energy-intensive raw material such as hydrogen, synthetic natural gas, fuel) applications have been proposed. At the heart of our work is widely used idea to convert residual CO2 from biogas plant into higher hydrocarbons using electricity from renewables (e.g., sun, wind, hydro). The specific goal is to produce ethylene-highly demanded hydrocarbon in plastics industry. The process itself is realised on electrocatalytic carbon/copper cathode which must be selective to reaction: 2CO2 + 12e− + 12H+→C2H4 + 4H2O. We propose a bottom-up approach to build catalyst from the smallest particles-graphene sheet stacks (GSS) coated with metallic copper nanocrystals. Composite GSS-Cu structure functions as a CO2 and proton absorber, facilitating hydrogenation and carbon–carbon coupling reactions on Cu-nanocluster/GSS for the formation of C2H4. In our design electrocatalytic electrode is made from nitrogen-doped graphene sheet stacks coated with copper nanostructures. The N-GSSitself can be drop-casted or electrophoretically incorporated onto the carbon paper and gas diffusion electrode. Electrochemical deposition method was recognized as successful and most promising to grow Cu nanocrystals on N-GSS incorporated in conducting carbon substrate. Gaseous products from CO2 electro-catalytic reformation on the cathode were investigated by mass-spectrometer but the electrode surface was analysed by SEM/EDS and XRD methods.

High‐Temperature Copper–Graphene Conductors via Aerosol Jetting

Additive manufacturing is transforming electronics, attributed to the rapid‐prototyping of complex electronic geometries. Herein, aerosol jet printing of nanostructured copper on ceramics is reported, enabling high‐temperature hybridized conductors with the ampacity of 2.05 × 109 A m−2 and a negative temperature coefficient of −0.07% °C−1 when subjected to extreme thermal shock. The atomized material jetting results in a layer‐by‐layer transfer of copper nanoplates, which incorporate a graphene precursor, dopamine, to ensure uniform deposition of conductive materials. Incorporation of graphene in copper maintains the intrinsic electric conductivity of copper while enhancing its ampacity and thermal conductivity, as well as exhibiting a negative temperature coefficient. The mechanistic studies suggest that the graphene formed suppresses the grain growth of the crystallites of hybridized copper–graphene conductor at high temperature. This hybridized conductor through aerosol jet printing is capable of withstanding elevated temperatures and can be utilized for the electronics for harsh environments.

Influence of Aluminum Doping on Structural and Optical Properties of the Nanostructured Copper Oxide Thin Films Prepared by CSP Method

Nanostructured CuO and CuO: Al+3 films were grown at various doping conditions via the chemical spray pyrolysis method (CSP). The crystallite size of the grown films obtained by XRD was (12.13-13.84) nm, the microstrain increased from 23.25 to 26.15. The topography of films was studied via AFM. The average diameter was noticed as (57.38), (69.45), and (75.38) nm for the (CuO, CuO: 2% Al3+ and CuO: 4% Al3+) respectively. A UV-Vis spectral analysis gained optical properties. The bandgap values in the range of (1.72-1.92) eV with the increase of Al3+ content. The absorption coefficient increases by aluminum doping. At the same time, the refractive index and Extinction coefficient increases with aluminum content. This result is beneficial for transparent thin films used for optoelectronic devices applications.

Physicochemical Properties and Antibacterial Activity of Nanostructured Copper Electrodeposited on Stainless Steel Surface

  Antimicrobial copper is beneficial in reducing hospital-acquired infections. Alteration of stainless steel by coating with copper makes the top surface antimicrobially active. In this study, nanostructured copper-coated stainless steel (Cu/SS) with excellent physicochemical properties and outstanding antibacterial activity was successfully prepared by electrodeposition technique. The physicochemical properties of the copper coating such as ultrafine nanostructured particles with grain diameter of 25 nm to 42 nm, rough surface with 24.23 nm, and low water contact angle (82o) would contribute in enhancing the antibacterial activity of the coating. Adhesion strength between the coating and stainless steel substrate is very good, as indicated by 100% of retainment of copper on the stainless steel surface tested using Scotch® tape. The antibacterial activity showed no significant difference between nanostructured copper-coated stainless steel and C11000 copper in terms of reduction of Staphylococcus aureus (S. aureus). However, only 5 minutes was required to completely kill Escherichia coli (E. coli) using nanostructured Cu/, while longer time (i.e., 10 minutes) using solid copper. The dissolution rate of nanostructured Cu/SS in simulated hand sweat solution was 0.08048 mm/year. The nanostructured copper coating also has high surface roughness and low surface wettability (i.e., high hydrophobicity). These findings indicate that the modification of stainless steel with copper nanostructures can improve the antibacterial activity of stainless steel. The Cu/SS coating can be an ideal material to be used as touch surface in combating bacterial infection, especially in hospitals and public areas.

Physicochemical Properties and Antibacterial Activity of Nanostructured Copper Electrodeposited on Stainless Steel Surface

  Antimicrobial copper is beneficial in reducing hospital-acquired infections. Alteration of stainless steel by coating with copper makes the top surface antimicrobially active. In this study, nanostructured copper-coated stainless steel (Cu/SS) with excellent physicochemical properties and outstanding antibacterial activity was successfully prepared by electrodeposition technique. The physicochemical properties of the copper coating such as ultrafine nanostructured particles with grain diameter of 25 nm to 42 nm, rough surface with 24.23 nm, and low water contact angle (82o) would contribute in enhancing the antibacterial activity of the coating. Adhesion strength between the coating and stainless steel substrate is very good, as indicated by 100% of retainment of copper on the stainless steel surface tested using Scotch® tape. The antibacterial activity showed no significant difference between nanostructured copper-coated stainless steel and C11000 copper in terms of reduction of Staphylococcus aureus (S. aureus). However, only 5 minutes was required to completely kill Escherichia coli (E. coli) using nanostructured Cu/, while longer time (i.e., 10 minutes) using solid copper. The dissolution rate of nanostructured Cu/SS in simulated hand sweat solution was 0.08048 mm/year. The nanostructured copper coating also has high surface roughness and low surface wettability (i.e., high hydrophobicity). These findings indicate that the modification of stainless steel with copper nanostructures can improve the antibacterial activity of stainless steel. The Cu/SS coating can be an ideal material to be used as touch surface in combating bacterial infection, especially in hospitals and public areas.

Rational design of Cu based composite electrode materials for high-performance supercapacitors – A review

Supercapacitors play a vital role in the storage of energy devices and in systems that assist in energy conversion. Currently, researchers focus on developing advanced materials to improve overall performance of the supercapacitors, and extensive efforts have been made towards scientific and technological advancements. The continuous progress towards composite materials hold enormous potential to circumvent present limitations, such as better architecture design of the materials to make it more durable, long cycle life, higher energy density, higher power density and better stability as well as being environment friendly to combat climate change. To address these limitations, the scope of advance electrode materials composed of copper nanostructures for the supercapacitor applications has been concentrated on this review. Apart from the versatile nature of copper oxide, it can be easily mixed with polarized liquids and polymers, thereby has very stable physical and chemical properties. We highlighting the numerous copper oxide hybrid metal oxide electrodes available to develop such supercapacitors. Consequent sections covered recent studies on composite nanostructures and electrodes based on copper oxide combined with organic compounds. Furthermore, we concluded the review and presented the challenges and prospects of this promising field.

A novel and controllable SERS system for crystal violet and Rhodamine B detection based on copper nanonoodle substrates

Copper nanostructures have attracted more and more attention due to low preparation cost, similar thermal conductivity and optical characteristics to silver nanostructures. A novel macroscopic dendritic copper nanonoodles with the length of 3–50 mm prepared by solid-state ionics method at 10 μA direct current electric field (DCEF) using fast ionic conductor RbCu4Cl3I2 films was reported. The surface-enhanced Raman scattering (SERS) performance of prepared copper nanonoodles was detected by crystal violet (CV) and rhodamine B (RB) aqueous solution as analyte molecules. The results present that the copper nanonoodles assembled by short-range order copper nanowires and the diameters of nanowires changed from 20 nm to 80 nm, many regularly arranged nanoparticles with the diameter from 5 to 10 nm existed on the prepared copper nanonoodles, which lead to the nanonoodles have high surface roughness. The copper nanonoodles contain only Cu element, no O element and the fractal dimension of copper nanonoodles is 1.355 because of macroscopic dendritic structures. The prepared copper nanonoodles composed of pure Cu have high surface roughness and the free electrons on the rough copper nanonoodles resonate with the atomic nuclei inside the copper nanonoodles to form a locally enhanced electromagnetic field under the excitation of incident light, so the limiting concentrations for CV and RB detected by the prepared copper nanonoodles are as low as 1 × 10−11 mol/L and 1 × 10−12 mol/L, respectively. The centimeter-scale copper nanonoodles with low limiting concentration of analyte molecules can be used to detect harmful food additives.

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.