Copper Oxide Nanostructures Research Articles

Droplet Jumping on Superhydrophobic Copper Oxide Nanostructured Surfaces

Condensation has been widely explored because of its importance in numerous applications including water desalination, water harvesting, power generation, and thermal management. Previous studies have shown that the enhancement in condensation heat transfer can be achieved with the engineering of surface wettability by promoting dropwise condensation that has lower thermal resistances than film condensation. In this paper, we explore microscopic-level droplet dynamics using various copper surfaces by employing a simple two-step chemical method. Nanostructured copper surfaces are prepared by a chemical immersion method using alkaline solution and are further functionalized by using dodecanoic acid that provides the hydrophobicity. The wetting properties and corresponding condensation processes are examined using an optical microscope and environmental scanning electron microscope by capturing the real-time phase change process. The measurements confirm that the surface morphology with the largest feature ratio promotes droplet jumping events. The understanding of condensation behaviors associated with nanostructured copper oxide surfaces can provide design rules for efficient surface structures for numerous condensation applications.

Effect of oxygen partial pressure on the tuning of copper oxide thin films by reactive sputtering for solar light driven photocatalysis

Nanostructured copper oxide thin films were deposited on soda lime glass substrates by reactive radio frequency (RF) magnetron sputtering using pure Cu target. The effect of oxygen (O2) partial pressure (5–50%) on physical properties of deposited films were investigated. The XRD analysis indicates the cubic structure of Cu2O changes to monoclinic CuO as a function of increasing O2 pressure. The Raman spectroscopy results further confirmed the phase variations of Cu based oxide films. Morphological analysis showed that the deposited films are highly uniform with nano gravels and agglomerated nano flake like structures for Cu2O and CuO thin films respectively. The surface roughness of the films decreases from 2.05 to 1.07 nm by increasing O2 pressure. X-ray photoelectron spectroscopy confirmed the binding energy variation in the oxidation state of the films. The optical band gap of deposited Cu2O is 2.12 eV, while that of CuO varies in the range of 1.79–1.82 eV. Hall effect measurement revealed that all the films exhibit p-type conductivity. The photocatalytic activity studies of as-deposited films have been carried out with different organic pollutants such as methylene blue, methyl orange and ciprofloxacin under solar irradiation. The Cu2O thin films exhibited higher degradation efficiency than CuO films under identical conditions. The mechanism of photocatalytic activity of copper oxide thin films is explained.

CeO2/CuOx Nanostructured Films for CO Oxidation and CO Oxidation in Hydrogen-Rich Streams Using a Micro-Structured Reactor

The CO oxidation reaction has a strong implication in environmental catalysis; besides a promising performance of CeO2/CuOx systems in inverse configuration has been demonstrated, in which ceria is deposited in larger copper oxide particles that act as support. In this work, in situ growths of nanostructured copper oxide films (CuOx) modified with ceria nanoparticles (Nps) were obtained, which were studied in the CO oxidation and the CO oxidation in hydrogen-rich streams (COProx). There was an effective stabilization of ceria Nps on the nanometric crystals of CuOx growths and the CeO2/CuOx films exhibited an enhanced activity in the oxidation of CO and COProx due to new active sites developed at the contact interface between both oxide nanostuctures. The microreactors were stable for 24 h in reaction at high conversion levels without deactivating, thus preserving the high synergy between CeO2 and CuOx. In COProx, the selectivity at high temperature was also improved by reducing the amount of oxygen in the reagents stream that lowered the contribution of the H2 oxidation undesirable reaction. Micro-structured reactors with inverse CeO2/CuOx phase have potential as a simple low cost alternative with high performance in the oxidation of CO in both air and hydrogen-rich streams.

Facile Synthesis and Phase-Dependent Catalytic Activity of Cabbage-Type Copper Oxide Nanostructures for Highly Efficient Reduction of 4-Nitrophenol

Cabbage-type morphology of cupric oxide (CuO) and cuprous oxide (Cu2O) nanostructures were synthesized via a simple and cost-effective chemical approach. HRTEM, FESEM, XRD, UV–Vis absorption and photoluminescence spectroscopies were used to identify the structural, optical, morphological and catalytic properties of the prepared nanostructures. Phase of the prepared copper oxide nanostructures was well controlled by changing the concentration of glucose. The prepared cabbage-type Cu2O nanostructures showed exceptionally improved catalytic performance towards the reduction of toxic 4-nitrophenol into useful 4-aminophenol as compared to cabbage-type CuO nanostructures. Cabbage-type Cu2O nanostructures completely transformed 4-NP into 4-AP in just 5 min with excellent rate constant (0.587 min−1). The observed excellent catalytic activity of prepared cabbage-type Cu2O nanostructures indicates their potential use in catalytic applications.

Surfactant determines the morphology, structure and energy storage features of CuO nanostructures

Abstract In quest for cost-affordable but high performing supercapacitor (SC), we explored fabrication of electrode material of copper oxide (CuO) nanostructures using simple solution-based synthesis procedure and different surfactants. Here, we report the influence of the surfactants on the morphological and structural evolutions as well as energy-storage capacity of the CuO. As an SC electrode material, CuO exhibits considerably high specific capacity (51 mAhg−1 @ 1Ag−1), good rate performance (31 mAhg−1 @ 10Ag−1) and better cyclic stability. In addition, it has low charge transfer resistance (1.6 Ω), which is very important when performing charge–discharge at high current rates. These results are highlighting the way for its use in design of advanced CuO-based supercapacitor devices.

PH-dependent synthesis of copper oxide phases by polyol method

Copper oxide nanostructures (Cu2O and CuO) were successfully synthesized via pH adjustments in a glycolic medium. XRD analysis confirmed the formation of cubic Cu2O at acidic condition and monoclinic CuO at basic condition. SEM images showed the production of copper oxide nanoparticles with sizes 90-96 nm and flower-like structures using the complex solution. Using UV-Vis spectroscopy, the measured band gap energies are 2.6 and 3.5 eV for Cu2O and CuO, respectively.

Effect of reaction time on structural, morphological, optical and photocatalytic properties of copper oxide (CuO) nanostructures

Spindle-like CuO nanostructure had been synthesized by facile hydrothermal method at low temperature of 100 °C. The influence of reaction time on the evolution of structure, morphology, optical and photocatalytic properties was investigated. X-ray diffraction analysis revealed the monoclinic phase. HR-SEM and TEM analyses evidenced morphological transformation with reaction time. XPS analysis revealed the composition and elemental state of CuO nanoparticles. The optical properties analysed by UV-absorption spectroscopy indicated that the band gap varied slightly within the range 3.43–3.56 eV. Photoluminescence spectra displayed violet, blue and green emissions for all synthesized nanostructures. The as-synthesized CuO nanostructures were effectively used to degrade methylene blue (MB) dye under UV-light irradiation; reaching a maximum efficiency of 85% for 12 h.

Ions-free electrochemically synthetized in aqueous media flake-like CuO nanostructures as SERS reproducible substrates for the detection of neurotransmitters.

The process of catalytic destruction of tumor cells can be strengthened by introducing copper(II) oxide nanostructures (CuONSs) with receptor's agonists/antagonists immobilized on their surface. Here we show a simple and reliable electrochemical method for the fabrication ions-free flake-like CuO nanostructures in a surfactant/ions free aqueous environment. For the determination of the metal surface plasmon, size, rheology, and structure of the fabricated nanostructures ultraviolet-visible (UV-Vis), Fourier-transform infrared (FT-IR), Raman, and X-ray photoelectron (XPS) spectroscopies as well as scanning electron microscope (SEM), high-resolution transmission electron microscopy with energy dispersive X-ray (HDTEM-EDS), X-ray powder diffraction (XRD), and dynamic light scattering (DLS) analysis were used. The fabricated nanostructures were used as highly sensitive, uniform, and reproducible sensors of a natural ligand (bombesin) of some types of metabotropic seven transmembrane G protein-coupled superfamily receptors (GPCRs), which are over-express on the surface of many malignant tumors. Surface-enhanced Raman scattering (SERS) was used to monitor the geometry of adsorbate, separate, enrich, and detect various bombesin C-terminal fragments. It has been shown that the type of used substrate, surface development, and ions present in the solution have little effect on the mode of adsorption.

Camellia Sinensis Leaf Extract Mediated Synthesis of Copper Oxide Nanostructures for Potential Biomedical Applications

Despite the great progress in nanotechnologies, to date, there is still a lack of definite knowledge on the effects of CuO nanoparticles on cancer cell lines. In this present work, CuO nanoparticles were synthesized using Tea (Camellia sinensis) leaf extract. The devised method provides a simple, cost-effective aqueous means of producing spherical copper oxide nanoparticles. Preliminary characterization of green synthesized CuO NPs was carried out using UV-Vis spectroscopy, XRD, FT-IR, Zeta Potential, TEM and SAED analysis. The average crystallite size of the CuO nanoparticles is estimated to be 22.44 nm and the band gap for CuO nanoparticles was found to be 1.54 eV which are higher than bulk CuO. TEM images of CuO NPs shows a spherical morphology with moderate size distribution of larger nanoparticles due to agglomeration. The average particle size obtained from TEM is in the range of 25-32 nm which agrees well with the crystallite size calculated from XRD. CuO NPs has negative zeta potential of -70.2 mV which could keep it suspension stability for longer period of time. The antibacterial activity test results revealed a highest inhibition zone of 21 mm for gram positive S.aureus. Gram positive Staphylococcus aureus and gram negative Klebsiella pneumonia depicted highest sensitivity to nanoparticles compared to other strains and was more adversely affected by the copper oxide nanoparticles. CuO NPs have been tested for their potent cytotoxic activity against MCF-7 (breast cancer cells) using MTT assay. CuO NPs at the concentration of 50 μg/ml decreased the viability of MCF-7 cells by 50%.The quantification of cellular CuO NPs uptake using the imaging revealed a clear dose dependent toxic activity

Capillary Wicking in Hierarchically Textured Copper Nanowire Arrays.

Capillary wicking through homogeneous porous media remains challenging to simultaneously optimize due to the unique transport phenomena that occur at different length scales. This challenge may be overcome by introducing hierarchical porous media, which combine tailored morphologies across multiple length scales to design for the individual transport mechanisms. Here, we fabricate hierarchical nanowire arrays consisting of vertically aligned copper nanowires (∼100 to 1000 nm length scale) decorated with dense copper oxide nanostructures (∼10 to 100 nm length scale) to create unique property sets that include a large specific surface area, high rates of fluid delivery, and the structural flexibility of vertical arrays. These hierarchical nanowire arrays possess enhanced capillary wicking ( K/ Reff = 0.004-0.023 μm) by utilizing hemispreading and are advantageous as evaporation surfaces. With the advent and acceleration of flexible electronics technologies, we measure the capillary properties of our freestanding hierarchical nanowire arrays installed on curved surfaces and observe comparable fluid delivery to flat arrays, showing the difference of 10-20%. The degree of effective inter-nanowire pore and porosity is shown to govern the capillary performance parameters, thereby this study provides the design strategy for capillary wicking materials with unique and tailored combinations of thermofluidic properties.

Influence of transition metal ion Ni2+ on optical, electrical, magnetic and antibacterial properties of phyto-synthesized CuO nanostructure

In the present work, nanostructured copper oxide (CuO) doped with various concentrations of Ni (0.003/0.006/0.009 M) ions were prepared using the Azadirachta indica (A. indica) leaf extract. X-ray diffraction patterns confirmed that synthesized nanoparticles have monoclinic structure. The nanoflower like morphology and chemical composition were identified using FESEM and EDX spectra. The characteristic Cu–O stretching band is observed in the FTIR spectra. UV–Vis spectra show band gap variation from 2.72 to 2.9 eV for pure CuO and Ni ion doped CuO NPs. Intensity of photoluminescence is found to increase with doping due to the substitution of Ni2+ ions into CuO lattice sites. Physical properties such as dielectric constant, dielectric loss and ac conductivity have been studied with regard to temperature, frequency and extent of doping. It is found that dielectric constant decreases with increase in frequency. The AC conductivity increases as temperature and frequency increase in all samples based on Koop’s phenomenological theory. Enhancement in saturation magnetization and ferromagnetic properties of Ni doped CuO has been observed in VSM studies taken at room temperature. The antibacterial studies performed against Gram positive (Staphylococcus aureus and Streptococcus pneumoniae) and Gram negative (Escherichia coli and Klebsiella pneumonia) bacterial strains show enhanced antibacterial activity on doping.

Effect of nano-coated CuO absorbers with PVA sponges in solar water desalting system

Nanostructured Copper Oxide (CuO) is coated on the stainless steel (SS) 316 substrates using thermal evaporation method. The effect of CuO nanostructured coated absorber plates (NCAP) integrated with Polyvinyl Alcohol (PVA) sponges is investigated in a single slope solar still (SSSS) for desalination. The experiment was conducted in the following configurations: (1) SSSS alone, (2) SSSS with CuO-NCAP, (3) SSSS with PVA sponges and (4) SSSS-CuO-NCAP with PVA sponges. Four identical SSSSs were built with 0.50 m2 collector area and tested under the same climatic conditions of Chennai, India during the period of March to April 2018. The CuO coated on the SS316 was characterized by Grazing Incidence X-ray Diffraction (GIXRD), Field emission Scanning Electron Microscope (FESEM) and Energy Dispersive Spectrum (EDS). The climatic parameters like ambient temperature, solar radiation and internal temperatures of the SSSS were measured at frequent intervals of time. The efficiencies of the SSSS, SSSS-CuO-NCAP, SSSS-PVA sponges and SSSS with CuO-NCAP-PVA sponges are 37%, 53%, 32% and 41% respectively. The productivity of SSSS, SSSS-CuO-NCAP, SSSS-PVA sponges and SSSS with CuO-NCAP-PVA sponges are 2144 ml/m2/day, 2995 ml/m2/day, 1970 ml/m2/day, and 2318 ml/m2/day, respectively. Therefore, the addition of the sponges was counterproductive, but the CuO-NCAP significantly increased output.

Highly porous nanostructured copper oxide foam fiber as a sorbent for head space solid-phase microextraction of BTEX from aqueous solutions

A highly porous copper foam was constructed on the surface of an unbreakable copper wire by a very rapid electrochemical method. Then, the copper oxide arrays were constructed on the pore surface of the copper foam by the thermal process. The applicability of the fiber was examined for the head space SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylene (BTEX) in different water samples followed by gas chromatography–flame ionization detection. A Plackett–Burman design was performed for screening the experimental factors to determine significant factors influencing method extraction efficiency. The effective factors were then optimized using Box–Behnken Design (BBD). Compared with the bare copper foam coating, copper oxide fiber has extraction ability for the target analytes, which is comparable with the extraction efficiencies obtained from commercial polydimethylsiloxane (PDMS) fiber with 100 μm thicknesses. Under optimum conditions, the developed method exhibited low limits of detection (0.12–0.41 μg L−1), low limit of quantification (0.40–1.36 μg L−1), wide linear range (1–500 μg L−1) with coefficient of determination >0.99, good relative standard deviations (6.9–9.6%) and good recoveries (higher than 88%), which confirm the capability of the prepared fibers in analysis of BTEX.

Mechanism and experimental evidence of rapid morphological variant of copper oxide nanostructures by microwave heating

In this work, the formation mechanisms under rapid microwave radiation of copper oxide nanofibers and copper oxide nanoparticles were proposed. The copper oxide nanofibers were synthesized by using only pure copper powders. Whereas, ethanol addition in pure copper powders significantly influenced nucleation and morphological formation of the copper oxide nanoparticles. Both nanofibers and nanoparticles were determined by X-ray diffractometer (XRD) showing a mixture of Cu2O and CuO phases. The mixed structures were clearly confirmed by transmission electron microscope (TEM). The copper oxide nanofiber diameters were in the range of 500–5,500 nm with an average length of about 2.5 cm and a circular cylindrical shape and smooth surface. The nanoparticles showed a spherical shape with homogeneous size in the diameter range of 80–120 nm. This report further investigated a formation mechanism using experimental results. The study showed that the formation could be attributed to surface reactions of ethanol in polar characteristic way that accumulated thermal into Cu powders.

Morphological and Electrochemical Properties of Bilayered Copper Oxide Nanostructures Directly Grown on Transparent Conductive Oxides by a Simple Wet-Chemical Process

We successfully synthesized copper oxide (CuO) nanostructures using an aqueous solution of copper acetate monohydrate without any surfactant at 90°C, and analyzed their morphological evolutions and electrochemical properties with different growth times. All samples consisted of polycrystalline single-phase monoclinic CuO. The CuO directly grown on transparent conductive oxide (TCO) substrates had a bilayered structure, with the bottom layer consisting of compact nanostructures formed from heterogeneous nucleation on the surface of the TCO substrate and the top layer comprising microspheres formed from homogeneous nucleation in the solution. The entirely binder-free bilayered CuO nanostructures prepared by the simple wet-chemical method exhibited an impressive specific capacitance with good cycling stability over 1000 cycles.

Toxicity of copper oxide nanoparticles to Neotropical species Ceriodaphnia silvestrii and Hyphessobrycon eques

The increase of production and consumption of copper oxide nanostructures in several areas contributes to their release into aquatic ecosystems. Toxic effects of copper oxide nanoparticles (CuO NPs), in particular, on tropical aquatic organisms are still unknown, representing a risk for biota. In this study, the effects of rod-shaped CuO NPs on the Neotropical species Ceriodaphnia silvestrii and Hyphessobrycon eques were investigated. We also compared the toxicity of CuO NPs and CuCl2 on these species to investigate the contribution of particles and cupper ions to the CuO NPs toxicity. Considering the low copper ions release from CuO NPs (<1%), our results revealed that the toxicity of CuO NPs to C. silvestrii and H. eques was mainly induced by the NPs. The 48 h EC50 for C. silvestrii was 12.6 ± 0.7 μg Cu L−1 and for H. eques the 96 h LC50 was 211.4 ± 57.5 μg Cu L−1 of CuO NPs. There was significant decrease in reproduction, feeding inhibition and increase in reactive oxidative species (ROS) generation in C. silvestrii exposed to CuO NPs. In fish H. eques, sublethal exposure to CuO NPs caused an increase in ROS generation in gill cells and an increase in cells number that were in early apoptotic and necrotic stages. Our results showed that CuO NPs caused toxic effects to C. silvestrii and H. eques and ROS play an important role in the toxicity pathway observed. Data also indicated that C. silvestrii was among the most sensitive species for CuO NPs. Based on predicted environmental concentration in water bodies, CuO NPs pose potential ecological risks for C. silvestrii and H. eques and other tropical freshwater organisms.

Synthesis of nanostructured transition metal oxides by a nanosecond discharge in air with assistance of the deposition process by plasma UV-radiation

The conditions for the synthesis of zinc, copper and iron oxides nanostructures using plasma nanosecond high-current discharge in air when introducing electrodes material vapor into a plasma due ectonic mechanism and the main parameters of the plasma are investigated. It is shown that this discharge can be used for the synthesis of nanoparticles of transition metal oxides on a dielectric substrate. Optical characteristics of nanostructures are given.

Studies on the influence of the physicochemical characteristics of nanostructured copper, zinc and magnesium oxides on their antibacterial activities

The influence of the physicochemical characteristics of nanostructured metal oxides on their antibacterial activities have been investigated. In this work, different shapes of copper, zinc and magnesium oxides nanoparticles have been synthesized. Type, purity and crystal properties of the prepared metal oxides were tested using the x-ray diffraction analyses. The shape and particle sizes were investigated using TEM measurements. Surface characteristics of the prepared metal oxides were also studied. The antibacterial studies on the prepared metal oxides were conducted on Gram positive (Bacillussubtilis and Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria by agar diffusion method. Overall, both CuO and ZnO showed high antibacterial activities. However, the antibacterial performance of MgO was significantly low. The physicochemical characteristics of CuO and ZnO nanoparticles significantly affect their antibacterial performance. For example, thin CuO nanorods (CuOnr1) showed higher antibacterial activities than the thick rods (CuOnr2). Thin polar facets of CuOnr1 probably easily penetrated into bacterial membranes. In addition, hexagonal ZnO sample (ZnOh2) possesses the highest total pore volume and the lowest particle size compared to the other ZnO samples. Consequently, ZnOh2 shows the highest antibacterial activities toward all bacteria under investigation. Contrary, the antibacterial activity of MgO does not significantly affected by the criteria of the prepared nanoparticles. It seems that the ability of MgO to launch the antibacterial process is quite low so the impact of their physical properties could not be detected.

Room-temperature growth (“farming”) and high-performance supercapacitor applications of highly crystalline CuO nanowires/graphene nanoplatelet nanopowders

We report a first-of-its-kind farming-like growth of nanopowders of CuO nanowires (NWs) via room-temperature thermal oxidation. Compared to conventional thermal annealing methods for producing copper oxide nanostructures, which require elevated temperatures (300–600 °C), the present method yields a large amount of highly crystalline CuO NW nanopowders at a much lower temperature (i.e., room temperature). Two-dimensional carbon nanostructures such as graphene nanoplatelets (GNPs) were used as supports for the growth of the CuO NWs. The GNPs were coated with Cu seed layers by the electroless plating method, which is suitable for mass production. After electroplating of Cu layers, the GNP supports were kept at room temperature and under constant humidity (50 or 60% relative humidity) for over 24 h, resulting in the dense wire-like morphology of copper oxide. Scanning electron microscopy, energy dispersive X-ray diffraction, X-ray diffraction, and Raman spectroscopy measurements revealed that the NWs consisted of highly crystalline monoclinic CuO. Once the NWs were formed, their morphology was stable for up to 168 h at room temperature. The as-prepared CuO nanopowders were tested as electrodes of electrochemical capacitors (or supercapacitors). In a three-electrode configuration, a working electrode made of CuO NWs exhibited an excellent mass-specific capacitance of 145 F g−1 at 5 mV s−1 in a 3 M KOH aqueous electrolyte. The growth of CuO nanopowders on GNPs illustrated in this study demonstrates a novel approach for the room-temperature synthesis of nanopowders, with promising applications in next-generation energy devices.

A novel impedimetric glucose biosensor based on immobilized glucose oxidase on a CuO-Chitosan nanobiocomposite modified FTO electrode

This research aims at elaborating on the construction of a novel nanostructured copper oxide (Nano-CuO) sputtered thin film on the conductive fluorinated-tin oxide (FTO) layer that was exploited to immobilize glucose oxidase (GOx) enzyme via chitosan for developing impedimetric glucose biosensing. The distinct Nano-CuO thin film was fabricated by reactive DC magnetron sputtering system at the optimized instrumental deposition conditions. The FTO/Nano-CuO/Chitosan/GOx biosensor containing several layers afforded excellent microenvironment for rapid biocatalytic reaction to glucose. Field emission-scanning electron microscopy (FE-SEM), Ultraviolet–Visible spectroscopy (UV–Vis), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were established the morphology of modified electrode's surface and electrochemical behavior of glucose on the fabricated biosensor. Characterization of the surface morphology and roughness of CuO thin film by FE-SEM exhibits cavities of the nanoporous film as an effective biosensing area for covalent enzyme immobilization. Invented FTO/Nano-CuO/Chitosan/GOx biosensor was employed for glucose determination using the impedimetric technique. The impedimetric outcomes display high sensitivity for glucose (0.261 kΩ per mM) detection within 0.2–15 mM and limit of detection as 27 μM. The declared biosensor has been applied as a careful, noncomplicated, and exact biosensor for recognition of glucose in the real samples analysis.