Seed Layer-Assisted Chemical Bath Deposition of Cu2O Nanoparticles on ITO-Coated Glass Substrates with Tunable Morphology,Crystallinity, and Optical Properties

A seed layer-assisted chemical bath deposition method performed at low temperature has been developed to grow uniform and high-quality crystal cuprous oxide (Cu₂O) nanoparticles on transparent conductive/glass substrates. The annealing process by continuous beam (CW) of CO₂ laser was used prior to growing the Cu₂O nanoparticles. In this study, the controlled synthesis of Cu₂O films was investigated by controlling the growth temperatures at 55 °C, 60 °C, 65 °C, and 70 °C, respectively. The modified seeding substrate reflect enhanced structural properties with laser annealing temperature of 450 ℃. In addition, Cu₂O nanoparticles with flower-like stricter show a greater density containing a smaller particle with 75 nm average dimension and flower particle size was about 85 nm. Results suggest an effective synthesis route for developing high-quality Cu₂O nanoparticles for optical and electronic applications.

     

Synthesis of pure Cu2O thin layers controlled by in-situ conductivity measurements

An easy synthesis route for cuprous oxide (Cu₂O) nanoparticles is reported via thermal annealing improved and controlled by in-situ conductivity measurements. The crystalline structure, phase transition, surface morphology and particle size/shape, were investigated through X-ray diffraction, a conductivity setup and scanning electron microscopy, respectively. X-ray diffraction patterns revealed that initial metallic Cu nanoparticles were transformed to Cu₂O nanoparticles with high purity, under specific conditions critically dependent on the temperature and annealing duration. This transformation was also dependent on the film thickness and atmospheric composition in the test chamber during the annealing process.     

Green sonochemical synthesis of cupric and cuprous oxides nanoparticles and their optical properties

Nanoparticles of cupric oxide (CuO) and cuprous oxide (Cu₂O) with various morphologies were synthesized by a green sonochemical process without any surfactants and templates. The Cu₂O nanoparticles with the truncated cubic, cubic octahedral and octahedral morphologies were prepared via the deoxidation of the CuO nanoparticles. The Cu₂O and CuO samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible absorption spectroscopy (UV–vis). The experimental results indicate that the molar ratio of sodium hydroxide to copper sulfate affects the morphology and size of the CuO and Cu₂O nanoparticles produced by the sonication. The band gap energy of CuO nanoparticles was 1.45–1.75 eV, the morphology had a great effect on the optical properties of CuO. The Cu₂O nanoparticles had broad emission peaks at the visible region, and the band gap energy was estimated to be 1.95–2.09 eV. The growth mechanisms of the CuO and Cu₂O nanoparticles are discussed.     

Fabrication of cubic PtCu nanocages and their enhanced electrocatalytic activity towards hydrogen peroxide

Cubic PtCu nanocages (NCs) were successfully synthesized through a redox reaction using cuprous oxide (Cu₂O) as a sacrificial template and reducing agent. The porous PtCu NCs were composed of amounts of PtCu nanograins with an average particle size of 2.9 nm. The electrocatalytic performance of the PtCu NC electrode towards H₂O₂ was studied by cyclic voltammetry (CV) and chronoamperometry. The prepared PtCu NC electrode exhibited excellent electrocatalytic activity towards H₂O₂, with a wide liner range from 5 μM to 22.25 mM, a relatively high sensitivity of 295.3 μA mM^-1 cm^-2, and a low detection limit of 5 μM (S/N = 3). The hollow porous nanostructure has potential applications in biosensors.     

Surfactant-free synthesis of Cu2O hollow spheres and their wavelength-dependent visible photocatalytic activities using LED lamps as cold light sources

A facile synthesis route of cuprous oxide (Cu₂O) hollow spheres under different temperatures without the aid of a surfactant was introduced. Morphology and structure varied as functions of reaction temperature and duration. A bubble template-mediated formation mechanism was proposed, which explained the reason of morphology changing with reaction temperature. The obtained Cu₂O hollow spheres were active photocatalyst for the degradation of methyl orange under visible light. A self-designed equipment of light emitting diode (LED) cold light sources with the wavelength of 450, 550, and 700 nm, respectively, was used for the first time in the photocatalysis experiment with no extra heat introduced. The most suitable wavelength for Cu₂O to photocatalytic degradation is 550 nm, because the light energy (2.25 eV) is closest to the band gap of Cu₂O (2.17 eV). These surfactant-free synthesized Cu₂O hollow spheres would be highly attractive for practical applications in water pollutant removal and environmental remediation.     

溶剂热法可控合成纳米氯化亚铜

以氯化铜为铜源,甲醇、乙醇、异丙醇等为溶剂和还原剂,采用溶剂热法制备纳米氯化亚铜,探讨了温度、时间、还原剂等条件对所得氯化亚铜的形貌、粒径大小、物相组成的影响。结果表明,以乙醇、异丙醇为溶剂,在120~180℃反应24~48 h,Cu Cl纳米颗粒可在2~50 nm范围内有效调控。     

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C₁₆-iron oxide (PHEA-C₁₆-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C₁₆-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C₁₆-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C₁₆. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C₁₆-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C₁₆-iron oxide nanoparticles. Therefore, PHEA-C₁₆-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes.     

Preparation and application of (Cu2O-Ag)@TA composite nanomaterials with enhanced stability and photocatalytic antibacterial activity

Food spoilage caused by bacterial growth is a serious threat to human health, so food preservation technology with long-acting antibacterial effect has been widely studied. In this work, (Cu₂O-Ag)@TA heterojunction composite antibacterial material with a core-shell structure was synthesized to improve the stability of Cu₂O. Morphological characterization shows that silver nanoparticles are uniformly distributed on the surface of Cu₂O microspheres, (Cu₂O-Ag)@TA has a core-shell structure, the particle size is about 300 nm, and the thickness of the tannic acid shell is about 6 nm. In addition, (Cu₂O-Ag)@TA exhibits excellent dispersibility and stability, it can stably release Cu²⁺ within 14 days and has enhanced reactive oxygen species release performance, thus achieving excellent antibacterial properties, with a minimum inhibitory concentrations of 96 μg ml⁻¹ against Escherichia coli and Staphylococcus aureus. In addition, adding (Cu₂O-Ag)@TA into the LbL-PVA/CS/FA composite film can improve the mechanical properties and antibacterial ability of the composite film, providing a feasible solution for new biodegradable antibacterial packaging materials.     

Fabrication of nanometer-to-micron sized Cu2O single crystals by electrodeposition

Nanometer-to-micron sized cuprous oxide (Cu₂O) single crystals were fabricated on Au/Pd sputter-coated silicon wafer and stainless steel cathode substrates by electrodeposition in CuSO₄ at pH 4.0 at room temperature (25 °C) with no additives. The Cu₂O crystals were generally of an octahedral shape with sizes ranging from 100 nm to 400 nm on Si wafer, and 1 μm to 3 μm on stainless steel substrates respectively. Very small crystals of a spherical shape were also observed under low applied voltage. Transient crystal shapes observed on the cathode near the electrolyte surface suggest that growth slows down once {1 1 1} free surfaces are formed, and this explains the robust observation of the octahedral crystal shape. The effect of electrodeposition parameters such as deposition voltage and deposition time on the size of the crystals and their coverage on the substrates was investigated. Apart from the cathode, similar octahedral Cu₂O nanocrystals were also found to deposit on the Cu anode used. This work provides a method to fabricate Cu₂O crystals on both electrodes in a single step.     

New versatile synthesis for low dimension superparamagnetic YBa2Cu3O7−x nanoparticles

This paper describes the synthesis and characterization of YBa₂Cu₃O_7−x (YBCO) nanoparticles obtained through an environmentally friendly chemistry approach. Y-, Cu- acetates and Ba trifluoroacetate were used for the synthesis of the precursor gel. Moreover, sucrose and pectin reagents were added as chelating agents inducing the formation of small size oxide nanoparticles. The thermal decomposition process of the precursor powder was investigated by thermal analysis correlated with mass spectrometry. The chemical nature, structure and morphology of the particles were investigated by X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy. According to XRD analysis the nanoparticles have an orthorhombic structure and the average diameter between 18–30 nm, additionally confirmed by TEM measurements. The superparamagnetic behavior at room temperature of the YBCO nanoparticles has been clearly evidenced by magnetization measurements. Furthermore, the effect of the annealing atmosphere on the magnetic properties has been studied.     

Size controlled synthesis of Pd nanoparticles inspired from the Wacker reaction and their catalytic performances

A novel and facile strategy for the synthesis of size-controlled Pd nanoparticles employing C₂H₄ as the reducing agent was inspired from the Wacker reaction. Uniform Pd nanoparticles with the size ranging from 3 nm to 50 nm were successfully synthesized by using different types of capping agents and optimizing the synthesis parameters. Pd nanoparticles with different sizes exhibit a size-dependent catalytic performance in the aerobic oxidation of benzyl alcohol that could be reasonably attributed to the surface blocking effect exerted by the capping agent chemisorbed on their surfaces and the likely electronic effect.     

Creating dual charge transfer channels to collaborative enhance the photocatalytic bacteriostatic efficiency and photocorrosion resistance of Cu2O based nanocomposites

Cuprous oxide (Cu₂O), as one of the traditional photocatalytic antifouling agents, has its own defects for practical applications such as rapid recombination of carriers, serious photocorrosion (Cu₂O changing into CuO) and explosive release of cuprous ions. Herein, a novel ternary interfacial heterojunction (Cu₂O/C/CCN) was prepared by carbon doping of g-C₃N₄ followed by in-situ carbon film covering and Cu₂O loading. Compared with pure Cu₂O and Cu₂O/g-C₃N₄, Cu₂O/C/CCN presented more powerful broad-spectrum and long-term photocatalytic antibacterial properties against S. aureus and P. aeruginosa, and the antibacterial rate remained at approximately 94.28% and 90.54%, respectively, even after storage 30 days. The high antibacterial rate of the Cu₂O/C/CCN can be attributed to the high photocatalytic performance and stable and continuous release of cuprous ions. The carbon doping of g-C₃N₄ could adjust its band gap and promote more efficient photoexcited carrier generation and transfer by the formation of delocalized large π bonds like “electron bridge” as the first charge transfer channel. The existence of carbon film between g-C₃N₄ and Cu₂O can build the second highly efficient charge transfer channel for the separation of photoexcited carriers by forming a Z-scheme interfacial heterojunction. DFT calculation and fluorescence spectrum results showed that more active electrons on CCN tend to transfer to Cu₂O through the two nonradiative decay pathways. The highly efficient carrier transport and separation can also greatly reduce the 15.3% generation of CuO compared to Cu₂O/g-C₃N₄. The more negative reduction potential further promoted the ROS generation for sterilization. In addition, the loading of Cu₂O on 2D C/CCN can reduce the contact area between Cu₂O and solution and then slow the release rate of cuprous ions by 75% compared to Cu₂O. Therefore, Cu₂O/C/CCN has great potential for practical antifouling applications.     

Fabrication and characterization of a new MRI contrast agent based on a magnetic dextran–spermine nanoparticle system

This study aims to fabricate and formulate a new magnetic resonance imaging (MRI) contrast agent based on a dextran?Cspermine nanoparticulate system loaded with super paramagnetic iron oxide nanoparticles (SPION). SPION-loaded spermine?Cdextran nanoparticles were prepared according to a procedure based on the ionic gelation of dextran?Cspermine with sodium tripolyphosphate (TPP) anions. The effects of process parameters such as pH, concentration of spermine dextran, TPP to dextran?Cspermine and SPION to dextran?Cspermine weight ratios, and TPP addition rate were fully investigated to find the optimized formulation through the response surface methodology. At the optimum condition, 75% of the magnetic iron oxide nanoparticles added to the polymeric solution were entrapped in dextran?Cspermine nanoparticles. Samples were investigated by transmission electron microscopy. The mean particle size of the nanoparticles determined by particle size analyzer was found to be 65?nm at the optimum condition with zeta potential of +90?mV. The SPION-loaded dextran?Cspermine nanoparticle formulation has the same superparamagnetic properties as SPIONs and at same iron concentration the saturation magnetization (Ms) of the SPION-loaded dextran?Cspermine nanoparticles was larger than SPIONs. In vitro MRI was performed with gradient echo and spin-echo sequences at 1.5?T. By increasing of iron concentration, the T ₂ relaxation times were reduced. Thus, indicating that the saturation magnetization and r ₂ and $ r_{2}^{*} $ relaxivities were enhanced, and the contrast effects were improved in comparison to commercial SPIONs.     

Shape-controlled synthesis of submicro-sized cuprous oxide octahedra

Monodisperse submicro-sized cuprous oxide (Cu₂O) octahedra are successfully prepared in large quantities assisted by the capping reagent poly(vinyl pyrrolidone) (PVP-K30, MW=58 000) and the formation mechanism of Cu₂O octahedra is analyzed.     

Continuous synthesis of metal nanoparticles in supercritical methanol

Metal nanoparticles were synthesized continuously in supercritical methanol (scMeOH) without using reducing agents at a pressure of 30 MPa and at various reaction temperatures ranging 150-400 °C. Wide angle X-ray diffraction (WAXD) analysis revealed that metallic nickel (Ni) nanoparticles were synthesized at a reaction temperature of 400 °C while mixtures of nickel hydroxide (α-Ni(OH)₂) and metallic Ni were produced at lower reaction temperatures of 250-350 °C. In contrast, metallic silver (Ag) nanoparticles were produced at reaction temperatures above 150 °C while metallic cupper (Cu) nanoparticles were produced at reaction temperatures above 300 °C. Mixtures of copper oxide (CuO and Cu₂O) and metallic Cu were produced at lower reaction temperatures of 250 °C. Scanning electron microscopy (SEM) showed that the particles size and morphology changed drastically as the reaction temperature increased. The average diameters of Ni, Cu and Ag particles synthesized at 400 °C were 119 ± 19 nm, 240 ± 44 nm, and 148 ± 32 nm, respectively. The scMeOH acted both as a reaction medium and a reducing agent. A possible reduction mechanism in scMeOH is also presented.     

Novel Microwave-Assisted Synthesis of Renewable-Resource Based Carbon-Magnetite Nanocomposites

Abstract

Magnetic carbon-iron oxide nanoparticles have been synthesized using tannin, a renewable resource material, in combination with a microwave-based thermolytic process without the addition of any inert or reducing gas during the synthesis. The predominant iron oxide species present in these particles has been determined by XRD and FT-IR to be magnetite (Fe₃O₄). These iron oxide nanoparticles are embedded within a carbon matrix in small clusters generally ≤100 nm in size. The resulting powder is approximately 48% (w/w) magnetite, and has been characterized by magnetic susceptibility and SQUID analysis.     

Mineral wool fibers incorporated with cuprous oxide for visible light photocatalytic inactivation of Escherichia coli

Mineral wool fibers (MWF) commonly used in building insulation and decoration are incorporated with cuprous oxide particles at room temperature to inactivate Escherichia coli (E. coli). X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet–visible diffuse reflection absorption spectroscopy (UV–vis/DRS) are employed to characterize the photocatalytic composites and the bactericidal effects are assessed by UV–visible spectrophotometry. Cuprous oxide particles with a size of 100 nm can be immobilized effectively on the surface of the MWF. The MWF improves the optical properties of cuprous oxide and red-shifts the band gap thereby enhancing the utilization efficiency of visible light. The Cu₂O/MWF composites deliver excellent photocatalytic performance in the inactivation of E. coli. After illumination for 24 h, more than 95% of the bacteria are inactivated and the materials are suitable for indoor antibacterial applications.     

Room-Temperature Electrochemical Assembly of Copper/Cuprous Oxide Nanocomposites

Nanocomposite films of copper metal and cuprous oxide, Cu₂O, are electrodeposited at room temperature from alkaline solutions of copper(II) lactate. The electrode potential oscillates spontaneously if the films are deposited galvanostatically. The oscillation period is a function of pH, varying from 69 seconds at pH 8.7 to 11 seconds at pH 9.7. No oscillations are observed if the pH is below 8.5 or above 10. The phase composition of films deposited at 0.5 mA/cm² is a function of pH. The composition varies from nearly pure copper (93 mole%) at pH 8, to 42 mole% copper at pH 9.5, to pure cuprous oxide when the pH exceeds 10. The observation of quasi-periodic potential oscillations suggests that the nanocomposites are layered. The calculated faradaic thickness of cuprous oxide is 5–8 nm, and the thickness of the copper layer is 1–11 nm. The thickness of each of the layers increases as the pH is lowered.     

Size‐Dependent Crystal Properties of Nanocuprite

Cuprite nanoparticles from 9 nm to 1 μm with narrow size distribution (±7%) are prepared by two different methods. The lattice parameter increases up to 0.2% as the crystallite size decreases to 9 nm from micron size. X‐ray Absorption Near Edge Spectroscope study of our copper oxide nanoparticles shows mostly Cu (I) with increasing concentration of Cu (II) as decreasing crystal sizes. The size effect in Cu(II)/Cu(I) ratio indicates that at smaller crystal size, the Cu₂O tends to be more oxidized at higher charge state with Cu(I)‐O bond. Thus, the lattice expansion can be explained by the presence of longer Cu (II)‐O bond than Cu (I)‐O bond and/or oxygen interstitials in nanocuprite.     

Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source

Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl₄ and PdCl₂ on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles.