CuO Nanostructures Research Articles

Preparation and characterization of structural properties for TiO2 and CuO nanostructures by sol-gel technique

The nano-powder synthesis of titanium dioxide nanoparticles (TiO2 NPs) from industrial titanium dioxide and sodium hydroxide and copper oxide nanoparticles (CuO NPs) from copper nitrate and citric acid by sol-gel technique. Powder X-ray diffraction (XRD), EDS, FESEM and TEM were used to characterize the resulted nano materials which are titanium dioxide nanoparticles and copper oxide nanoparticles. The characterization measurements prove that the titanium dioxide nanoparticles were prepared with an average crystallite size of 17.25 nm, while the average crystallite size of copper oxide nanoparticles were found to be 15.33 nm. According to SEM investigation, the crystalline form appeared as a sphere like nanostructure or nano cluster, with the resulting nanoparticles having a polyhedral shape. TEM analysis at the nanoscale confirmed the spherical morphology of the produced copper oxide nanoparticles and titanium dioxide nanoparticles. However, the method that used here for the preparation of copper oxide nanoparticles and titanium dioxide nanoparticles could be considered a very promising method for such preparation.

Direct growth of three-dimensional nanoflower-like structures from flat metal surfaces.

Here we report on a facile top-down approach for the direct growth of Co3O4 hierarchical nanoflowers from a bulk Co surface via chemical etching and thermal annealing. The effect of the annealing temperature was investigated, showing that amorphous Co3O4 was formed at 250 °C, while crystalline Co3O4 with notable oxygen vacancies was created at 550 °C. The formed 3D nanostructures exhibited excellent oxygen evolution reaction (OER) activities with a low overpotential of 0.34 V at 10 mA cm-2 and high durability. The proposed novel approach was further demonstrated by the direct growth of 3D NiO and CuO nanostructures on Ni and Cu substrates.

A Symmetry-Based Approach to the Characterization of Complex Surface Morphologies: Application in Cuo and Nio Nanostructures

A Symmetry-Based Approach to the Characterization of Complex Surface Morphologies: Application in Cuo and Nio Nanostructures

Rietveld analysis of X-ray diffraction pattern of sol-gel synthesized copper oxide nanoparticles

We adopted a cost-effective sol-gel method to synthesize copper oxide (CuO) nanoparticles. Formation of well crystalline CuO nanostructures without any impurity was confirmed from the X-ray diffraction (XRD) pattern of the prepared materials. It is also evident that no CuO phase is present in the material. The growth of the nanocrystal was found to be anisotropic as revealed from the intensities of the diffraction peaks. The crystallite size was calculated using the Scherrer formula. It was further observed that the variation of precursor concentration leads to change in the crystallite size. We performed a detail chemistry of this precursor concentration dependence of the growth. Various structural parameters like crystallite size, strain, dislocation density, lattice parameters and specific surface area were calculated from the analysis of the X-ray diffraction pattern. Rietveld simulation for detail analysis of the structure of the synthesized CuO nanoparticles revealed the monoclinic unit cell with lattice parameters : a=4.705511Å, b=3.439857Å, c=5.148335Å, α=γ=90° and β=99.403°. The other Rietveld fitting parameters were also evaluated. The values of Rp, Rwp and Rexp were found to be 4.127%, 5.329% and 4.723% respectively with a χ value of 1.128 which justifies the goodness of fitting.

Sapindus mukorossi seed shell extract mediated green synthesis of CuO nanostructures: an efficient catalyst for C–N bond-forming reactions

An effective biogenic approach is proposed to synthesize size-tunable CuO nanostructures using seed shell extract of Sapindus mukorossi plant to use as efficient catalysts for conjugate addition of amines to acrylonitrile under ambient conditions.

Leaf-like copper oxide mesocrystals by collagen-assisted biomineralization show attractive biofunctional and electrochemical properties

A robust one-pot strategy based on collagen-templated biomineralization has been developed to create hierarchical CuO nanostructures with a good electrochemical performance.

Influence of manganese and nickel doping on optical and electric properties of CuO nanostructures for optoelectronic applications

Influence of manganese and nickel doping on optical and electric properties of CuO nanostructures for optoelectronic applications

Influence of Manganese and Nickel doping on Optical and Electric Properties of CuO Nanostructures for Optoelectronic Applications

Influence of Manganese and Nickel doping on Optical and Electric Properties of CuO Nanostructures for Optoelectronic Applications

Synthesis and chemoresistive sensitivity to hydrogen of nanostructured CuO films

Highly porous CuO films up to 1 μm thick consisting of vertically oriented nanowires ~ 50 nm in diameter were synthesized by copper evaporation in a vacuum arc discharge in an argon/oxygen atmosphere followed by deposition on heated substrates. The phase composition and polycrystalline nature of the films were confirmed by X-ray diffraction. On the example of gaseous hydrogen H2 at a sensor operating temperature of 300oC, sensory characteristics of CuO films were studied. The qualitative mechanism of the effect of gas on the electrical characteristics of the nanostructured CuO film is described. Keywords: copper oxide, vacuum arc, nanowires, gas sensor.

Синтез и хеморезистивная чувствительность к водороду наноструктурированных пленок CuO

Highly porous CuO films up to 1 µm thick, consisting of vertically oriented nanowires ~50 nm in diameter, were synthesized by copper evaporation in a vacuum arc discharge in an argon/oxygen atmosphere followed by deposition on heated substrates. The phase composition and polycrystalline nature of the films were confirmed by X-ray diffraction. On the example of gaseous hydrogen H2, at a sensor operating temperature of 300 °C, the sensory characteristics of CuO films were studied. The qualitative mechanism of the effect of gas on the electrical characteristics of the nanostructured CuO film is described.

Copper oxide nanoleaves covered with loose nickel oxide nanoparticles for sensitive and selective non-enzymatic nitrite sensors

In this work, we developed a new method for preparing copper oxide (CuO) nanostructures, designed and prepared a CuONiO modified fluorine-doped SnO2 transparent conductive glass (FTO) electrode for electrochemical sensor to effectively detect the nitrite. The leaf-shaped CuO nanostructures grow uniformly on the FTO electrode, resulting in the increased contact area and reduced transfer resistance. The NiO nanoparticles effectively dispersed in the gaps between the leaves can further improve the electron transfer and reduce the diffusion resistance. The electrochemical results demonstrated that the prepared electrode exhibited high sensitivity (7.2 mA mM−1 cm−2), broad linear range (0.001–1.8 mM) and low detection limit (0.013 μM). Moreover, the prepared sensor also reflected good reproducibility, stability and anti-interference in the detection of actual samples, which provides a good application prospect for metal oxides used in water quality and environmental monitoring.

Determination of the Influence of Various Factors on the Character of Surface Functionalization of Copper(I) and Copper(II) Oxide Nanosensors with Phenylboronic Acid Derivatives.

In this work, we attempt to determine the influence of the oxidation state of copper [Cu(I) vs Cu(II)], the nature of the interface (solid/aqueous vs solid/air), the incubation time, and the structure of N-substituted phenylboronic acids (PBAs) functionalizing the surface of copper oxide nanostructures (NSs) on the mode of adsorption. For this purpose, 4-[(N-anilino)(phosphono)-S-methyl]phenylboronic acid (1-PBA) and its two analogues (2-PBA and bis{1-PBA}) and the copper oxide NSs were synthesized in a surfactant-/ion-free solution via a synthetic route that allows controlling the size and morphology of NSs. The NSs were characterized by scanning electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, and X-ray diffraction, which confirmed the formation of spherical Cu2O nanoparticles (Cu2ONPs) with a size of 1.5 μm to 600 nm crystallized in a cubic cuprite structure and leaf-like CuO nanostructures (CuONSs) with dimensions of 80–180 nm in width and 400–700 nm in length and crystallized in a monoclinic structure. PBA analogues were deposited on the surface of the copper oxide NSs, and adsorption was investigated using surface-enhanced Raman spectroscopy (SERS). The changes in the orientation of the molecule relative to the substrate surface caused by the abovementioned factors were described, and the signal enhancement on the copper oxide NSs was determined. This is the first study using vibrational spectroscopy for these compounds.

Antibacterial Activity of CuO Nanoparticles Synthesized by Justicia adhatoda Leaf Extract

Aims: To determine the antibacterial activity of CuO nanoparticles (CuO NPs) synthesized by Justicia adhatoda leaf extract.
 Study Design: Synthesis, characterization and antibacterial activity determination of CuO NPs.
 Place and Duration of Study: PG and Research Department of Chemistry, V.O.Chidambaram College, Tuticorin, Tamilnadu, India, between April 2019 and April 2020.
 Methodology: CuO NPs were synthesised using Justicia adhatoda leaf extract. UV-Visible spectroscopy was used to characterize CuO NPs. The role of biomolecules in plant extract in the formation of the CuO NPs was identified using Fourier transform infrared spectroscopy. The particle size and lattice properties of CuO NPs were determined using XRD. The surface morphology of CuO NPs was studied using SEM. The presence of Cu and O in CuO NPs was confirmed using EDAX analysis. Bacterial antimicrobial activity was investigated.
 Results: An absorbance band at 285 nm in the UV–visible spectrum clearly revealed the formation of CuO NPs. In the FTIR, CuO NPs had a distinct absorption peak at 608 cm-1, confirming metal–oxygen stretching in Cu-O nanostructures. The presence of crystalline CuO NPs was confirmed by XRD patterns, and they were found to be spherical in shape with a size range of 23.21–37.57 nm, as evidenced by FESEM. The biosynthesized CuO NPs exhibited a strong antibacterial activity against Staphylococcus epidermidis and Bacillus cereus bacteria.
 Conclusion: Justicia adhatoda leaf extract mediated CuO NPs have shown significant antibacterial activity and they are considered potent antibacterial agents.

Characterization of octahedral Cu2O nanostructures grown on porous silicon by electrochemical deposition

Cuprous oxide (Cu2O) nanostructures on porous silicon (PSi) were obtained by an electrochemical deposition method. The effects of current density and deposition time on structural, optical and I–V characteristics of PSi/Cu2O nanostructures were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) methods, diffuse reflectance spectra and current-voltage (I–V) measurements. SEM analysis revealed that the shape of Cu2O nanostructures was mostly truncated octahedral and pyramid, and their size increased with increasing deposition time and current density. From XRD analysis, it was found that Cu2O nanostructures were polycrystalline, cubic phase and their preferential orientation was along the [111] direction. In addition, it was found that with increasing current density, the average crystallite size of Cu2O nanostructures decreased, whereas FWHM, micro deformation and dislocation values increased. The diffuse reflectance spectra indicated that the average reflectivity of PSi/Cu2O samples obtained in 30 and 60 min deposition times are about 19%. The current-voltage (I–V) measurements of PSi/Cu2O samples at room temperature (300 K) and in the dark environment revealed that samples exhibited rectifier properties and behaved like a typical p-n junction diode. In addition, it was found that the I–V parameters obtained from thermionic emission and Cheung's model are found to depend on the deposition time and current density. The PSi/Cu2O sample prepared at 0.5 mA/cm2 for 60 min had the smallest ideality factor and series resistance among all samples. The values of ideality factor and barrier height were determined using the conventional thermionic emission (TE) model and Cheung's model and the obtained results have been compared with each other.

Alteration of pool boiling heat transfer on metallic surfaces by in situ oxidation

The critical heat flux during pool boiling has been investigated for a range of applications including electrical power generation and thermal management. Reported experimental CHF values during pool boiling of water on flat metallic surfaces, however, show a large discrepancy across studies. Here, we address this discrepancy in CHF values by accounting for oxidation of metallic surfaces during boiling. We studied the effect of in situ oxidation on flat Cu and Ni surfaces by changing the duration that samples were held in saturated water before conducting boiling experiments. The morphology and chemical composition of surfaces after the boiling experiments were analyzed by atomic force microscopy and X-ray photoelectron spectroscopy, respectively. Cu surfaces showed gradually increasing CHF values as the duration in saturated water increased, which could be attributed to the increase in roughness due to the formation of Cu2O nanostructures. Conversely, Ni surfaces showed relatively stable CHF and morphology as a nearly flat layer of NiO formed, with one exception: formation of a highly wetting hydroxide, Ni(OH)2, on a Ni coupon held in saturated water for 24 h resulted in a uniquely high CHF value, signifying the importance of surface chemistry in addition to morphology. The fundamental mechanisms resulting in the wide spread of CHF values on metallic surfaces elucidated in this work will lead to more accurate estimation of CHF as well as a deeper mechanistic understanding of CHF values on engineered surfaces.

A Promising Three-Step Heat Treatment Process for Preparing CuO Films for Photocatalytic Hydrogen Evolution from Water.

Copper (II) oxide (CuO) nanostructures were prepared on fluorine-doped tin oxide (FTO) using a three-step heat treatment process in a sol–gel dip-coating method. The precursor used for the dip-coating process was prepared using copper acetate, propan-2-ol, diethanolamine, and polyethylene glycol 400. Dip-coated films in layers of 2, 4, 6, 8, and 10 were prepared by drying each layer at 110 and 250 °C for 10 and 5 min, respectively, followed by calcination at 550 °C for 1 h. The films were applied toward photocatalytic hydrogen evolution from water. The X-ray diffraction (XRD) pattern of the films confirmed the tenorite phase of pure CuO. Raman spectroscopy revealed the 1Ag and 2Bg phonon modes of CuO, confirming the high purity of the films produced. The CuO films absorb significant photons in the visible spectrum due to their low optical band gap of 1.25–1.33 eV. The highest photocurrent of −2.0 mA/cm2 at 0.45 V vs reversible hydrogen electrode (RHE) was recorded for CuO films consisting of six layers under 1 sun illumination. A more porous surface, low charge transfer resistance, and high double-layer capacitance at the CuO/electrolyte interface observed for the films consisting of six layers contributed to the high photocurrent density attained by the films. CuO films consisting of six layers prepared using the conventional two-step heat treatment process for comparative purposes yielded 65.0% less photocurrent at 0.45 V vs RHE compared to similar films fabricated via the three-step heating method. The photocurrent response of the CuO nanostructures prepared using the three-step heat treatment process is promising and can be employed for making CuO for photovoltaic and optoelectronic applications.

Room Temperature Surface Oxidation by Alkalization of Binder Free CuO Nanostructured Electrode for Enhanced Supercapacitive Performance

AbstractThe copper oxide (CuO) nanostructures are synthesized via facile oxidation of Cu foil in an aqueous KOH solution at room temperature. A precleaned Cu foil immersed in a 0.1 M aqueous KOH solution for different time periods (36–72 h) systematically converts its surface into nanochained to rice husk morphology and then agglomerated dense nanoclusters. The impact of immersion time on the morphology and consequently supercapacitor performance is studied. The CuO nanostructure synthesized at an immersion time of 60 h shows a maximum specific capacitance of 302 Fg–1 at a scan rate of 2 mV s−1. The capacitance retention reaches up to 87% after 2000 cycles.

Comparative Studies on Synthetic Strategies for the Growth of CuO Nanostructures and Their Significant Impact on Supercapacitive Performance

AbstractThe copper oxide (CuO) nanostructures are synthesized by various simple and cost‐effective chemical methods. The morphology of metal oxide nanostructures depends on the synthetic strategy. The electrochemical behavior primarily depends on the morphology of the electrode. The significant impact of synthetic strategy on the structural, morphological, and subsequently on the supercapacitive performance of CuO nanostructures is studied. The chemical bath deposition (CBD) leads to well defined growth of 1D nanostructures, while the intermittent growth process (successive ionic layer adsorption and reaction, SILAR) leads to nanoparticulate morphology. CBD grown CuO nanorods have shown comparatively higher capacitance (207 F g−1) than CuO nanoparticles (147 F g−1) at current density of 2 A g−1.

Hierarchical CuO nanostructured materials for acetaldehyde sensor application

A nanocrystalline CuO with mixed morphologies (nanorods, nanoplates and nanoparticles) were prepared using simple room temperature wet chemical synthesis route. The nanostructured CuO material was characterized using FESEM, TEM, EDS, elemental mapping, UV–visible spectroscopy, and BET surface area techniques for various physicochemical characteristics. The gas sensor device was fabricated using CuO nano-powder and its acetaldehyde gas sensing properties was investigated. The CuO sensor showed excellent sensing response towards 20–100 ppm acetaldehyde. The acetaldehyde response of the CuO sensor was recorded at various operating temperatures as well as concentrations. The responses of 418% and 115% were noted for 100 ppm and 20 ppm acetaldehyde concentration at 180 °C respectively. The higher selectivity of the CuO sensor was observed towards acetaldehyde among various gases. The transient response of the sensor was observed to be consistent with concentrations. The dynamic repetitive response of the sensor was tested at 100 ppm acetaldehyde that revealed to be same. The sensor's stability was tested and observed to be quite stable. A brief acetaldehyde sensing mechanism for CuO sensor was elucidated. The easy and large-scale formation of CuO nanostructures without growth controlling surfactants, and the good selectivity of the high response acetaldehyde sensor at relatively low operating temperatures may pave pathway for future gas sensor technology.

Plasma-enhanced thermal growth of copper oxide nanostructures on anode of glow discharge setup

Plasma-enhanced growth of copper oxide nanostructures is widely explored in science and manufacturing, since it provides the flexibility, productivity, and cost-effectiveness necessary to meet the growing demands of customers. However, in the field of growth of metal oxide nanostructures, thermal methods still prevail in plasma methods in spite of long production time up to ten hours. Radiofrequency and microwave plasma sources were applied to grow CuO nanostructures, which are of high interest in various branches of industry, and allowed obtaining a large variety of the nanostructures, and nanowires in particular. At that, high price of the equipment limits the implementation of the results and urges to find cheaper plasma-enhanced method of growth. For this purpose, a common glow discharge plasma setup was engaged to grow the nanostructures in an oxygen atmosphere on surfaces of samples installed on the anode of the electric circuit designed to sustain the glow discharge. An additional heater was mounted under the anode. The proposed combination allowed conducting the growth process under conditions of the delivery of the necessary heat flux and removal the excessive ion flux that can destroy the growing nanostructures because of sputtering. In the first set of experiments, the additional heater was not used, and the observed nanostructures were presented by grains (2D) of about 370 nm in diameter and 80 nm in thickness. This structure is supposedly formed because of action of the internal stresses in the oxide layer. After turning on the heater, the nanowires (1D) were the only nanostructures observed in the experiment, and since no nanowires were found in a case of heating the anode without plasma ignition, one can consider the plasma as a factor determining the nanowire growth.