Colloidal Cu2O Research Articles

Integrating Cu2O Colloidal Mie Resonators in Structurally Colored Butterfly Wings for Bio-Nanohybrid Photonic Applications.

Colloidal Cu2O nanoparticles can exhibit both photocatalytic activity under visible light illumination and resonant Mie scattering, but, for their practical application, they have to be immobilized on a substrate. Butterfly wings, with complex hierarchical photonic nanoarchitectures, constitute a promising substrate for the immobilization of nanoparticles and for the tuning of their optical properties. The native wax layer covering the wing scales of Polyommatus icarus butterflies was removed by simple ethanol pretreatment prior to the deposition of Cu2O nanoparticles, which allowed reproducible deposition on the dorsal blue wing scale nanoarchitectures via drop casting. The samples were investigated by optical and electron microscopy, attenuated total reflectance infrared spectroscopy, UV-visible spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry. It was found that the Cu2O nanoparticles integrated well into the photonic nanoarchitecture of the P. icarus wing scales, they exhibited Mie resonance on the glass slides, and the spectral signature of this resonance was absent on Si(100). A novel bio-nanohybrid photonic nanoarchitecture was produced in which the spectral properties of the butterfly wings were tuned by the Cu2O nanoparticles and their backscattering due to the Mie resonance was suppressed despite the low refractive index of the chitinous substrate.

Characteristics of copper oxide and tin oxide nanoparticles produced by using pulsed laser ablation method and their application as an antibacterial agent

The synthesis of copper oxide (CuO) and tin oxide (SnO2) nanoparticles was successfully carried out using the neodymium yttrium aluminum garnet (Nd:YAG) laser ablation method. In this study, a laser beam was focused on the surface of high-purity (99.9%) Cu and Sn plates placed into deionized water (DIW) and 0.2% carboxymethyl cellulose (CMC) liquid media, respectively, to produce colloidal CuO and SnO2 nanoparticles. CuO and SnO2 nanoparticle colloids were successfully produced with greenish and brownish colors, respectively. The colloidal nanoparticles produced in CMC media are more stable. Thus, the antibacterial test on E. coli bacteria uses CuO and SnO2 samples in CMC media. Antibacterial assessments were carried out using disc diffusion and liquid dilution methods equipped with total plate counting (TPC) techniques, with a sample variation of 26 ppm CuO, 78 ppm SnO2, and a CuO-SnO2 mixture of 5:56 ppm and 19:19 ppm samples. The results of the disc diffusion test yielded the diameter of the bacterial inhibition zone. The diameter of the inhibition zone in CuO 26 ppm, SnO2 78 ppm, and CuO-SnO2 5:56 ppm and 19:19 ppm samples, respectively, were 7.43 mm, 6.39 mm, 7.18 mm, and 6.54 mm, while the liquid dilution test equipped with TPC produced the percentage of bacterial degradation, respectively, of 98.93%, 97.60%, 98.47%, and 97.73%. The results show that all variations had the effectiveness of inhibiting and killing bacteria. From the results of various bacterial tests, colloidal CuO nanoparticles are more effective than the SnO2 nanoparticles.

Novel Copper Oxide Bio-Nanocrystals to Target Outer Membrane Lectin of Vancomycin-Resistant Enterococcus faecium (VREfm): In Silico, Bioavailability, Antimicrobial, and Anticancer Potential.

In present study, we used Olea europaea leaf extract to biosynthesize in situ Copper Oxide nanocrystals (CuO @OVLe NCs) with powerful antibacterial and anti-cancer capabilities. Physio-chemical analyses, such as UV/Vis, FTIR, XRD, EDX, SEM, and TEM, were applied to characterize CuO @OVLe NCs. The UV/Vis spectrum demonstrated a strong peak at 345 nm. Furthermore, FTIR, XRD, and EDX validated the coating operation's contact with colloidal CuO @OVLe NCs. According to TEM and SEM analyses, CuO @OVLe NCs exhibited a spherical shape and uniform distribution of size with aggregation, for an average size of ~75 nm. The nanoparticles demonstrated a considerable antibacterial effect against E. faecium bacterial growth, as well as an increased inhibition rate in a dose-dependent manner on the MCF-7, PC3, and HpeG2 cancer cell lines and a decreased inhibition rate on WRL-68. Molecular docking and MD simulation were used to demonstrate the high binding affinity of a ligand (Oleuropein) toward the lectin receptor complex of the outer membrane to vancomycin-resistant E. faecium (VREfm) via amino acids (Leu 195, Thr 288, His 165, and Ser 196). Hence, our results expand the accessibility of OVLe's bioactive components as a promising natural source for the manufacture of physiologically active components and the creation of green biosynthesis of metal nanocrystals.

Detection of low-level humic acid in water using room temperature-synthesized copper (I) oxide colloids

Abstract

Thermal decomposition of ammonium perchlorate catalyzed with CuO nanoparticles

Abstract Ammonium perchlorate (APC) is the most common oxidizer in use for solid rocket propulsion systems. However its initial thermal decomposition is an endothermic process that requires 102.5 J·g−1. This manner involves high activation energy and could render high burning rate regime. This study reports on the sustainable fabrication of CuO nanoparticles as a novel catalyzing agent for APC oxidizer. Colloidal CuO nanoparticles with consistent product quality were fabricated by using hydrothermal processing. TEM micrographs demonstrated mono-dispersed particles of 15 nm particle size. XRD diffractogram demonstrated highly crystalline material. The synthesized colloidal CuO particles were effectively coated with APC particles via co-precipitation by using fast-crash solvent–antisolvent technique. The impact of copper oxide particles on APC thermal behavior has been investigated using DSC and TGA techniques. APC demonstrated an initial endothermic decomposition stage at 242 °C with subsequent two exothermic decomposition stages at 297.8 °C and 452.8 °C respectively. At 1 wt%, copper oxide offered decrease in initial endothermic decomposition stage by 30%. The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 53%. These novel features can inherit copper oxide particles unique catalyzing ability for advanced highly energetic systems.

Facile synthesis of CuO nanoparticles deposited zeolitic imidazolate frameworks (ZIF-8) for efficient photocatalytic dye degradation

Herein, we investigated the synthesis and characterization of new CuO nanoparticles (CuO NPs) deposited Zeolitic Imidazolate Frameworks (ZIF-8) photocatalyst with higher catalytic ability for dye degradation. ZIF-8 cubes (∼ 80 nm) were synthesized via a sol-gel method. CuO NPs were deposited on the cubic ZIF-8 surfaces through in-situ nucleation and growth process. The structures and morphology of the CuO NPs/ZIF-8 nanocomposites were established with the results of PXRD analysis, transmission electron microscopic (TEM) images, optical properties, FT-IR spectroscopy and thermo gravimetric analysis (TGA). The as-synthesized material was selected as a photocatalyst to decompose rhodamine 6G (Rh6G) dye. The ultra-small colloidal CuO nanoparticles (~ 5 nm) deposited ZIF-8 photocatalyst exhibited efficient photocatalytic activity for Rh6G degradation under sunlight irradiation. The Rh6G degradation followed a pseudo-first-order kinetics model. Nanocomposite containing 5-wt% of CuO nanoparticles content exhibits highest photocatalytic activity towards dye degradation. The CuO NPs deposited ZIF-8 also worked effectively over a wide pH range from 5.0 to 12.0 and showed high degradation efficiency in alkaline environment. Rh6G dye degradation is enhanced significantly in H2O2 solution. The possible pathway for photocatalytic degradation of Rh6G dye in nanocomposites was proposed. The results indicated that nanocomposites can be used as a highly efficient photocatalyst to decompose organic pollutants.

Nanothermite colloids: A new prospective for enhanced performance

Abstract Nanothermites (metal oxide/metal) can offer tremendously exothermic self sustained reactions. CuO is one of the most effective oxidizers for naonothermite applications. This study reports on two prospectives for the manufacture of CuO nanoparticles. Colloidal CuO particles of 15 nm particle size were developed using hydrothermal synthesis technique. Multiwalled carbon nanotubes (MWCNTs) with surface are 700 m2/g was employed as a substrate for synthesis of CuO-coated MWCNTs using electroless plating. On the other hand, aluminium particles with combustion heat of 32000 J/g is of interest as high energy density material. The impact of stoichiometric nanothermite particles (CuO/Al & Cuo-coated MWCNTs/Al) on shock wave strength of Al/TNT nanocomposite was evaluated using ballistic mortar test. While CuO-coated MWCNTs decreased the shock wave strength by 15%; colloidal CuO enhanced the shock wave strength by 30%. The superior performance of colloidal CuO particles was correlated to their steric stabilization with employed organic solvent. This is the first time ever to report on fabrication, isolation, and integration of stablilized colloidal nanothermite particles into energetic matrix where intimate mixing between oxidizer and metal fuel could be achieved.

Stabilized super-thermite colloids: A new generation of advanced highly energetic materials

One of the great impetus of nanotechnology on energetic materials is the achievement of nanothermites (metal-oxide/metal) which are characterized by massive heat output. Yet, full exploitation of super-thermites in highly energetic systems has not been achieved. This manuscript reports on the sustainable fabrication of colloidal Fe2O3 and CuO nanoparticles for thermite applications. TEM micrographs demonstrated mono-dispersed Fe2O3 and CuO with an average particle size of 3 and 15nm respectively. XRD diffractograms demonstrated highly crystalline materials. SEM micrographs demonstrated a great tendency of the developed oxides to aggregate over drying process. The effective integration and dispersion of mono-dispersed colloidal thermite particles into energetic systems are vital for enhanced performance. Aluminum is of interest as highly energetic metal fuel. In this paper, synthesized Fe2O3 and CuO nanoparticles were re-dispersed in isopropyl alcohol (IPA) with aluminum nanoparticles using ultrasonic prope homogenizer. The colloidal thermite peraticles can be intgegrated into highly energetic system for subsequent nanocomposite development. Thanks to stabilization of colloidal CuO nanoparticles in IPA which could offer intimate mixing between oxidizer and metal fuel. The stabilization mechanism of CuO in IPA was correlated to steric stabilization with solvent molecules. This approach eliminated nanoparticle drying and the re-dispersion of dry aggregates into energetic materials. This manuscript shaded the light on the real development of colloidal thermite mixtures and their integration into highly energetic systems.

Comparison of CuO nanoparticle and CuO/MWCNT nanocomposite for amplification of chemiluminescence immunoassay for detection of the hepatitis B surface antigen in biological samples

Nowadays, chemiluminescent immunoassay (CLIA) has gained increasing attention in different fields, including clinical diagnosis and environmental monitoring because of its high sensitivity and specificity, simple equipment and wide linear range. In this study, the colloidal CuO nanoparticles and CuO/MWCNT nanocomposite as the efficient nanocatalysts were introduced and compared for amplification of the luminol CLIA system. In the present work, we applied the antibody-nanomaterials conjugate without horseradish peroxidase (HRP) enzyme as the CLIA reaction catalyst. The CuO nanoparticles-antibody conjugates and CuO/MWCNT nanocomposite-antibody conjugates were prepared using the covalent binding. The results show that CuO nanoparticles and CuO/MWCNT nanocomposite enhance the luminol chemiluminescence intensity, significantly. Under the optimal conditions, the calibration plot for the standard sample of the hepatitis B surface antigen and chemiluminescence intensity was approximately linear within the range of 3.5×10−9–2.5×10−6 and 2.2×10−9–5.0×10−6gml−1. The limit of detection for the assay using CuO nanoparticles and CuO/MWCNT nanocomposite were 1.8 and 0.85ngml−1, respectively, which these results were comparable to that achieved of the enzyme-linked immunosorbent assay. The present CLIA method based on the new antibody-nanomaterials conjugates and chemiluminescence system has introduced for first time and offered great promise for simple and sensitive analysis of biological samples.

Thiol Adsorption on and Reduction of Copper Oxide Particles and Surfaces.

The adsorption of 1-dodecanethiol at room temperature and at 75 °C on submicron cuprous and cupric oxide particles suspended in ethanol has been investigated by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy. Thiol adsorption occurs in all cases via Cu-S bond formation, with partial dissolution of CuO at 75 °C and formation of a copper-thiolate complex replacement layer. Regardless of temperature, the surface of the CuO particles is essentially completely reduced to either Cu2O or metallic copper, as evidenced by loss of the characteristic Cu(2+) XPS features of dried powder samples. Companion ultrahigh-vacuum studies have been performed by dosing clean, oxygen-dosed, and ozone-treated single crystal Cu(111) with methanethiol (MT) gas at room temperature. In the latter case, the surface corresponds to CuO/Cu(111). XPS confirms MT adsorption in all cases, with an S 2p peak binding energy of 162.9 ± 0.1 eV, consistent with methanethiolate adsorption. Heating of MT-covered Cu(111) and oxygen-dosed Cu(111) leads to decomposition/desorption of the MT by 100 °C and formation of copper sulfide with an S 2p binding energy of 161.8 eV. Dosing CuO/Cu(111) with 50-200 L of MT leads to only partial reduction/removal of the CuO surface layers prior to methanethiolate adsorption. This is confirmed by ultraviolet photoelectron spectroscopy (UPS), which measures the occupied states near the Fermi level. For both the colloidal CuO and single crystal CuO/Cu(111) studies, the reduction of the Cu(2+) surface is believed to occur by formation and desorption of the corresponding dithiol prior to thiolate adsorption.

Colloidal Moderate-Refractive-Index Cu₂O Nanospheres as Visible-Region Nanoantennas with Electromagnetic Resonance and Directional Light-Scattering Properties.

Moderate-refractive-index dielectric nano-spheres are found to possess strong electric and magnetic dipole resonances in the visible region. Owing to the overlap of the electric and magnetic dipole resonances, moderate-refractive-index dielectric nanospheres exhibit directional forward scattering at the strongest scattering peak. Such directional scattering is experimentally observed on colloidal Cu2O nanospheres, which are readily prepared through wet-chemistry methods.

Synthesis of Vertically Conformal ZnO/CuO Core–Shell Nanowire Arrays by Electrophoresis-Assisted Electroless Deposition

Vertically conformal ZnO/CuO core–shell nanowire (NW) arrays with high aspect ratios were synthesized by electrophoresis-assisted electroless deposition (EAELD) of CuO onto preformed ZnO NWs. Using this method, conformal CuO seeds were successfully formed on long ZnO NWs by the electrostatic attachment of colloidal Cu2O NPs under the solution and subsequent thermal oxidation. Using the CuO seeds, conformal CuO shell to core ZnO NWs were successfully fabricated by kinetic-limited deposition in the solution, which overcame the inherent diffusion limitations of conventional electroless deposition. This experimental evidence and thermodynamic modeling results are presented to validate the proposed EAELD mechanism. The vertically conformal hetero-nanostructure arrays developed in this work are a promising platform for applications such as solar cells and catalysts because of the maximized junction areas and active sites.

Synthesis and optical properties of colloidal CuO nanoparticles

Copper oxide nanoparticles of sizes ranging from 1 to 25nm were synthesized using a colloid microwave-thermal method, where the average size of CuO nanoparticles can be tailored by controlled microwave treatment time. The particle size was found to significantly decrease as the microwave processing time increases and can be controlled to have narrow size distributions. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the sizes of the prepared nanoparticles. The UV–visible absorption spectra of the nanoparticles are blue-shifted with the size reduction, and this is attributed to quantum-confinement (QC) effect. Furthermore, the photoluminescence spectra showed UV and visible emissions, and were red shifted with increasing particles size and excitation wavelength. While the former observation confirms the QC effect and corroborates the results of UV–visible absorption spectra, the latter one is attributed to selective near band-edge excitonic transitions associated with defect states.

Electro-optical and magnetic properties of monodispersed colloidal Cu2O nanoparticles

A facile synthesis of colloidal cuprous oxide (Cu2O) nanoparticles has been reported via co-precipitation route. Crystalline structure/phase identification, surface morphology, particles size/shape were investigated through X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques, respectively. Transmission electron microscope investigations reveal that the synthesized nanoparticles are uniform and having spherical shape with average size of ∼6nm. The optical properties were probed through Fourier transform infrared spectroscopy, Raman spectroscopy and ultraviolet–visible spectroscopy. Energy band gap studies of the Cu2O nanoparticles reveal the possibility of both, direct and indirect optical transitions. Magnetic properties of the synthesized nanoparticle have been measured through vibrating sample magnetometer technique and the obtained result shows that the synthesized nanoparticles posses weak ferromagnetic nature at room temperature. Electrochemical response studies of Cu2O/indium tin oxide electrode have been carried out using cyclic voltammetry and electrochemical impedance spectroscopy. It is observed that the electrode prepared using the colloidal Cu2O nanoparticle shows excellent selectivity and sensitivity for these measurements, which can further be utilized for an efficient electrochemical based biosensor applications.

Photoelectrochemical studies on colloidal copper (I) oxide/modified with some organic semiconductors: Incentive for use of nanoparticle systems

Colloidal Cu2O solutions were used to explore photonic activities at the semiconductor/electrolyte interface. Fluorescence spectroscopic studies were performed on Cu2O colloidal particles modified with some conjugated organic monomers such as 2-amino-phenyl pyrrole (2-APPy), tri-phenyl amine (TPA), or 2-thionyl pyrrole (2-Th-Py) to investigate the quantum absorbance efficiency at this inorganic/organic interface (IOI). Our study shows that colloidal p-type Cu2O possesses a bandgap with direct transition of ≈ 2·2 eV and indirect transition of 1·85 eV. The recorded rates of charge injection into colloidal Cu2O, k ct, were 2·31 × 109 s−1, 5·05 × 108 s−1, and 7·22 × 108 s−1 for 2-APPy, TPA and 2-Th-Py, respectively. The studied systems show more stability in colloidal form than in thin solid form. Results were interpreted using the optical and electrical parameters of the organic monomer such as ionization potential (IP), electron affinity (EA) and energy bandgap (Eg), and the barrier height at the IOI interface. Stability of the colloidal system is attributed to the physical dimensions of the photoactive system. The nano-colloidal particle offers a condition where its size is less than √Dt.

Formation of Colloidal CuO Nanocrystallites and Their Spherical Aggregation and Reductive Transformation to Hollow Cu2O Nanospheres

In this work, we demonstrate that cuprous oxide Cu(2)O nanospheres with hollow interiors can be fabricated from a reductive conversion of aggregated CuO nanocrystallites without using templates. A detailed process mechanism has been revealed: (i) formation of CuO nanocrystallites; (ii) spherical aggregation of primary CuO crystallites; (iii) reductive conversion of CuO to Cu(2)O; and (iv) crystal aging and hollowing of Cu(2)O nanospheres. In this template-free process, Ostwald ripening is operative in (iv) for controlling crystallite size in shell structures and thus for precisely tuning the optical band gap energy (E(g)) of resultant semiconductor nanostructures. For the first time, a wealth of colorful Cu(2)O hollow nanospheres (outer diameters in 100-200 nm), with variable E(g) in the range of 2.405-2.170 eV, has been fabricated via this novel chemical route. Considering their unique hollow structure and facile tuning in band gap energy, the prepared Cu(2)O hollow spheres can be potentially useful for harvesting solar energy in the visible range. Possibility of fabrication of Cu-Cu(2)O nanocomposites has also been discussed.

Formation and Absorption Spectrum of Copper Nanoparticles from the Radiolytic Reduction of Cu(CN)2-

Colloidal copper particles (20−100 nm) are formed in the γ-irradiation of aqueous solutions of KCu(CN)2, which also contain methanol or 2-propanol as OH scavenger. The radiation chemical yield is of the order of 0.1 Cu atoms formed per 100 eV absorbed radiation energy and decreases with increasing concentration of excess KCN. A reduction mechanism is proposed, in which the hydrated electron reacts with Cu(CN)2-, whereas organic radicals attack a copper-I species, possibly colloidal Cu2O, present in low concentration by partial hydrolysis of Cu(CN)2-. Free copper atoms do not appear as intermediates in this mechanism. The optical absorption spectrum of Cu particles of different size is also reported; it contains the plasmon band in the 560−580 nm region and a UV band at 222 nm and becomes flatter with increasing particle size. The copper particles have almost spherical shape when formed at high irradiation dose rates but exhibit very pronounced polyhedra and rodlike contributions at low-dose rates.

Formation of Fractal Clusters of Colloidal Copper Hydrous Oxides

AbstractThe fractal dimensions of colloidal particles of copper hydrous oxides in the presence of natural occurring anionic exopolymers are reported from measurements using both small‐angle X‐ray‐ and static light scattering techniques. The power law decay of the structure factor [S(k) ∼ k −D] of colloidal copper hydrous oxides dispersions can be explained in terms of fractal geometry. D is found to be 2.15 ± 0.05 for Cu(OH)2, and for colloidal Cu2O·x H2O aggregates a value of 1.75 ± 0.07 was determined.

Formation of Colloidal Copper Hydroxides and Oxides Biopolymeric Interfaces

ABSTRACTLight sensitive colloidal particles of copper hydrous oxides were prepared at interfaces of exopolymeric materials. Dislike copper oxide or hydroxide nanoclusters were obtained which might be useful as p-type semiconductors. The colloidal Cu2O xH2O and Cu(OH)2 particles reveal fractal dimensions of D = 2.15 ±0.05 for Cu(OH)2 and D= 1.75 ±0.07 for Cu2O xH20.

Mechanism of Red Colour Formation in Photosensitive and Normal Copper-Ruby Glasses

Absorption spectra relating to the photosensitive copper-ruby and normal copper-ruby glasses revealed a strong absorption band at 560 mμ. The shapes of the absorption curves for the photosensitive copper-ruby and normal copper-ruby glasses were almost similar. Electron microscopic study also revealed the presence of the particles of colloidal copper in the size range of 20–60 mμ both in photosensitive as well as in the normal copper-ruby glasses. The results obtained showed that the red colour formation in copper-ruby glasses was due to the presence of the particles of colloidal copper, and not due to the particles of colloidal Cu2O.