CuO Nanopowder Research Articles

Photoelectrochemical Hydrogen Production by Screen-Printed Copper Oxide Electrodes

In this work, copper oxides-based photocathodes for photoelectrochemical cells (PEC) were produced for the first time by screen printing. A total 7 × 10−3 g/m2 glycerine trioleate was found as optimum deflocculant amount to assure stable and homogeneous inks, based on CuO nano-powder. The inks were formulated considering different binder amounts and deposited producing films with homogenous thickness, microstructure, and roughness. The as-produced films were thermally treated to obtain Cu2O- and Cu2O/CuO-based electrodes. The increased porosity obtained by adding higher amounts of binder in the ink positively affected the electron transfer from the surface of the electrode to the electrolyte, thus increasing the corresponding photocurrent values. Moreover, the Cu2O/CuO system showed a higher charge carrier and photocurrent density than the Cu2O-based one. The mixed Cu2O/CuO films allowed the most significant hydrogen production, especially in slightly acid reaction conditions.

Simulation of sinusoidal enclosure filled with nanoparticles enhanced PCM

Freezing of NEPCM within a tank has been investigated by means of Galerkin approach. NEPCM is mixture of water and CuO nano-powders with fraction of 0.04. In calculation of features of NEPCM, two shapes of nano-powders were utilized. Due to time dependent process, one source term was added to energy equation. Two important features of utilized technique are automatic time step and adaptive grid. Nice agreement with experimental data was illustrated. Influences of shape factor and amplitude of adiabatic wall have been examined. Choosing Platelet powder instead of sphere can accelerate the process about 8.344% when A = 0.1. Besides, with rise of A, the freezing time grows about 44.991% when m = 3. The efficient case in term of freezing time is case with A = 0.1 and m = 5.7 in which 198.27 s needs to reach full freezing.

Improved synthetic method of Benzo[a]pheno-selenazinium phototherapeutic agents

Benzo[a]phenoselenazinium dyes are excellent photodynamic therapeutic agents that have a red absorption (660 nm), high singlet oxygen quantum yield (>0.8), and good water-solubility and liposolubility. Bis-(3-diethylaminophenyl) diselenide, the most important intermediate for the synthesis of benzo[a]phenoselenazinium dyes, is previously prepared in one pot through 3 steps, during which special care is needed for the preparation of Grinard reagent and toxic selenium vapor. In this work, we employed CuO nanopowder to directly couple haloaniline with selenium to obtain pure bis-(3-diethylaminophenyl) diselenide (one step) under a mild condition with a high reaction yield without the need of column chromatography. Four benzo[a]phenoselenazinium dyes, 5a-d, were easily prepared using the improved synthesis method; and their phototoxicity in living cells were investigated. The improved method could be employed in large-scale synthesis of benzo[a]phenoselenazinium dyes, thereby may stimulate the photodynamic study of this type of photosensitizer.

Investigation of Microstructural Features, Phase Composition, and Magnetic Characteristics of YBCO-Based Composites and Additives of CuO Non-Superconducting Component Prepared in Low-Pressure Arc Discharge Plasma

A method making it possible to form HTS ceramics of non-superconducting coating consisting of self-organizing CuO crystals, whose sizes are less than the coherence length, i.e., within several tens of nanometers, has been developed. It has been shown that the combination of self-organizing structures in the form of whiskers and nanoparticles which arise as a result of combined sintering of YBa2Cu3O(7–x) powders and electric arc CuO nanopowders results in a significant increase in the current density and appearance of peak effect at high magnetic fields. Very high current density arises from the complex vortex pinning, where whisker defects provide high pinning energy and nanoparticles suppress flux creep. The morphology of such structures can be controlled by a simple change in the concentration of nanodisperse additives. It has been shown that 20 wt % of CuO additive is optimal.

Synthesis and optical properties of copper oxide nanoparticles: effect of solvents

Nanocrystalline copper oxide (CuO) powder was synthesized through solid-state co-precipitation technique using copper sulfate pentahydrate and sodium hydroxide pellets as a source materials. Crystalline nature and surface morphology of the sample are studied through x-ray diffraction, field emission scanning electron microscopy, energy dispersive x-ray, and Fourier transform infrared spectroscopy. Optical properties of synthesized CuO nanopowder were investigated by UV–Vis absorption and photoluminescence spectroscopy. X-ray diffraction study reveals that CuO nanoparticles are in monoclinic structure and crystalline size is found to be around 15 nm as estimated from Debye-Scherrer formula. FESEM measurement confirms that the particles are in almost irregular shape, and some nanorod-like structures are noticed. FTIR spectrum confirms the formation of high-quality and pure CuO nanoparticles. The effect of various solvents on optical properties of CuO nanoparticles is studied. From UV–Vis absorption measurement, a strong quantization along with varying band edges in different solvents was observed. It is seen from photoluminescence spectra that the intensity of emission as well as emission peak wavelength changes with solvents.

Phase change process of nanoparticle enhanced PCM in a heat storage including unsteady conduction

Abstract Thermal energy release process during solidification of water has been simulated in current investigation. Time-linked equation was solved via Galerkin approach and automatic time step has been considered. To augment thermal characteristics, NEPCM has been fabricated by embedding copper oxide in to water. Low deviation with experimental data confirms the accuracy of current code. With reduce of concentration of nanomaterial, process prolonged and higher temperature of domain has been reported. Selecting greater shape factor yields to stronger conduction mode which can result unit with lower solidification time. There was an approximate 1.34% reduction in discharging time with augment of shape factor and such percentage reaches to 4.6% for nanomaterial with 0.04 volume fraction. There is reducing tendency in time of solidification with augment of concentration of nanomaterial and outputs showed that 14.39% reduction for platelet CuO nano powders. Energy released reduces as time augments due to reduction in mass of liquid phase.

Solidification of PCM with nano powders inside a heat exchanger

Abstract Present research was devoted to modeling investigation of paraffin solidification within a wavy channel. Paraffin was mixed with CuO nano powders and creates NEPCM. Changing the surface of duct and working PCM is the main factors of this paper for improving the performance. The outer duct contains NEPCM and air within inner side can be warmer due to discharging process. The outputs indicate that wavy duct has better performance than the straight one due to its shorter solidification duration. Utilizing wavy duct and NEPCM can help the solidification and enhance the rate of process about 38%. Inclusion of nanomaterial leads to lower discharging time.

Cost-effective sol-gel synthesis of porous CuO nanoparticle aggregates with tunable specific surface area

CuO nanoparticles (NPs) are applied in various key technologies, such as catalysis, energy conversion, printable electronics and nanojoining. In this study, an economic, green and easy-scalable sol-gel synthesis method was adopted to produce submicron-sized nanoporous CuO NP aggregates with a specific surface area > 18 m²/g. To this end, a copper-carbonate containing precursor was precipitated from a mixed solution of copper acetate and ammonia carbonate and subsequently calcinated at T ≥ 250 °C. The thus obtained CuO nanopowder is composed of weakly-bounded agglomerates, which are constituted of aggregated CuO NPs with a tunable size in the range of 100–140 nm. The CuO aggregates, in turn, are composed of equi-axed primary crystallites with a tunable crystallite size in the range of 20–40 nm. The size and shape of the primary CuO crystallites, as well as the nanoporosity of their fused CuO aggregates, can be tuned by controlled variation of the degree of supersaturation of the solution via the pH and the carbonate concentration. The synthesized submicron-sized CuO aggregates can be more easily and safely processed in the form of a solution, dispersion or paste than individual NPs, while still offering the same enhanced reactivity due to their nanoporous architecture.

Investigation of catalyzed thermal recycling for glass fiber‐reinforced epoxy using fluidized bed process

An investigation of the effect of metal catalysts on thermal recycling of glass fiber‐reinforced epoxy was carried out within a fluidized bed system. CuO nanopowder was integrated with epoxy to assess its ability in reducing the epoxy thermal stability and in turn reducing the typical temperatures required thermal recycling for epoxy composites. It was found that the CuO was able to significantly accelerate the thermal degradation of the selected epoxy. The CuO loading of 5 wt% of epoxy provided the largest reduction in thermal stability and activation energy of the second stage of decomposition. It was also demonstrated that the addition of CuO did not negatively affect epoxy mechanical properties or curing and in fact increased the epoxy glass transition temperature. When applied to glass fiber‐epoxy (GF‐epoxy) recycling within the fluidized bed process, glass fibers were recycled at just 400°C with a yield of up to 59%. POLYM. COMPOS., 40:3510–3519, 2019. © 2019 Society of Plastics Engineers

Structure and optical properties of nanoparticles obtained by pulsed laser ablation of copper in gases

Nano-powders of different composition and structure were obtained by nanosecond pulsed laser ablation (Nd:YAG laser, 7 ns, 1064 nm, 20 Hz, 200 mJ) of a metallic copper target in a simple flow reactor at atmospheric pressure. The crystal structure, nanoparticles’ shape, and surface morphology were shown to depend on the gaseous media used (Ar, N2, CO2). CuO nanopowders with a specific surface area 50 m2/g were synthesized by pulsed laser ablation in carbon dioxide and after annealing in air. The optical properties of the obtained powders were also investigated.

Optical characterization of tungsten doped CuO nanoparticles produced through Micro-EDM

Abstract Study of doped nanoparticles draws more attention by many researchers due to its excellent properties. In this investigation, optical performance is carried out of tungsten doped CuO nanoparticles produced through Micro-EDM process. Pure and tungsten doped CuO nano powders (5, 10, 15, 20 and 25 % of W) have been produced by varying frequency of micro-EDM. The produced tungsten doped CuO nanoparticles were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. The size of nanoparticles is depicted by UV-Vis spectroscopy which indicate smaller size nanoparticles are fabricated at 30V.

Embedding CuO Nanoparticles in PDMS-SiO2 Coating to Improve Antibacterial Characteristic and Corrosion Resistance

The purpose of this paper was to develop the hydrophobic nanocomposite coatings of polydimethylsiloxane (PDMS)-SiO2-CuO to improve biocompatibility, corrosion resistance and antibacterial property of 316 L stainless. In this research, after synthesize of CuO and SiO2 nanopowders using wet-chemical approaches, PDMS-SiO2-CuO coatings consisting of various amounts of CuO nanoparticles were developed using dip-coating process. The nanocomposite coatings were characterized with regard to the structural and physical properties, corrosion resistance, antibacterial activity and cellular interactive responses. The results showed that incorporation of CuO nanoparticles <2 wt% improved the corrosion resistance of 316 L stainless steel. At higher CuO nanoparticle contents (>1 wt%), the agglomeration of nanoparticles and their cytotoxic effects resulted in reduced antibacterial characteristics and MG63 cell viability and proliferation. In summary, PDMS-SiO2-CuO nanocomposite coating with significant antibacterial and anticorrosion behavior could be a promising coating for biomedical implants.

Solar thermal conversion and thermal energy storage of CuO/Paraffin phase change composites

A nanofluid phase change material (PCM) is prepared by adding a small amount of CuO nanopowders to paraffin, for use in solar thermal conversion, thermal storage, and thermoelectric applications. Results show that adding CuO nanopowders to paraffin can greatly improve the solar thermal conversion capacity by enhancing the light absorption ability of PCMs. The steady temperature increased with increasing mass fraction of CuO NPs at low mass concentrations (0–0.1%). The largest increase was about 2.3 times that of the pure paraffin with comparable latent heat. In the solar thermoelectricity experiments, the open-circuit voltage improved (1.35 V) with the CuO/Paraffin composite (fm = 0.1%) under the same conditions, and was almost 1.8 times that of the pure paraffin. More importantly, a unique feature of the CuO/Paraffin composite PCM is the extension of thermal release, which enables the continuation of the voltage output when the solar simulator is switched off. The introduction of a very low mass concentration of CuO nanopowders can endow the composite PCMs with strong solar absorption ability, and contribute to realizing efficient solar thermal and solar thermoelectric energy conversion and storage. This provides a new prospect for solar radiation usage efficiency and direct solar energy conversion and utilization.

Combustion Characteristics of Physically Mixed 40 nm Aluminum/Copper Oxide Nanothermites Using Laser Ignition.

This paper reports on the ignition and flame propagation characteristics of aluminum/copper oxide (Al/CuO) nanothermite at different packing density, manufactured from 40 nm commercial Al and CuO nanopowders. A 3.5 W continuous wave laser was used to ignite the samples in argon at atmospheric pressure, and a high speed camera captured the flame propagation. The high speed images revealed that the fast laser heating creates significant material ablation, followed by heat transfer along the heated surface. The bulk ignition occurs near the edge of the top surface, followed by the self-sustained burning. Lightly pressed powders (90% porosity) ignited in ~0.1 ms and the burning front propagated at around 200 m/s, while the dense pellets (40–60% porosity) ignited in ~1 ms and the burning front propagated at around 10 m/s. These results indicate that the reaction mechanism changes from mass convection to heat diffusion with increasing the packing density. The ignition and burn speeds of these Al/CuO nanothermites at different equivalence ratios (ERs), along with SEM images of pre- and post-combustion, illustrate that the homogeneity of the mixture is a critical parameter for optimizing the performance. The Al rich mixtures show significantly lower ignition delays and higher burn speeds.

Synthesis of Copper Oxide Nanopowder by Microwave Method

Copper oxide nanopowder was successfully synthesized by microwave method. Copper acetate and sodium hydroxide were used as the starting precursors. The microwave power was set to 800 Watt for 2-6 min and fine black nanopowder was obtained. The nanopowder was milled and dried at 80 °C for 12 h. The structure was identified by X-ray diffractometer (XRD). A monoclinic single phase of CuO nanopowder structure was obtained without calcination steps. The morphology was investigated by scanning electron microscope (FESEM). The particle was irregular in shape and agglomerated. The chemical composition was determined by energy dispersive X-ray spectrometer (EDXS). The chemical compositions showed the characteristic X-ray energy of copper (Kα=8.048 keV) and oxygen (Kα=0.525 keV), respectively. The functional group was investigated by fourier transform infrared spectrometer (FTIR). The functional groups of the vibration Cu-O bending showed the wavenumber at 491-615 cm-1.

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.

Localization and transfer of charge carriers in CuO nanopowder by impedance spectroscopy

Particular electro-physical characteristics of CuO nanopowder were investigated by impedance spectroscopy using a sensor based on interdigitated structure in the frequency range from 1 Hz to 100 MHz. The results of investigation were considered. Simulation of impedance spectra by equivalent electric circuits was carried out for numerical approximations of the frequency dependences of the dielectrical permittivity and conductivity. Electric charge accumulation of on the boundaries of nanoparticles and near the metal electrodes of the sensor was revealed. It was shown that a double electric layer is formed near the electrodes, which leads to the appearance of anomalously large values of dielectrical permittivity and an increase in the conductivity in the low-frequency region. The obtained results can be explained by proton conductivity in the nanopowder caused by moisture which is adsorbed on the surface of the nanoparticles. It was shown that after high-temperature annealing of CuO nanopowders, accumulation of electric charges was not observed. It was established that hopping or polaron conductivity occurs in the annealed CuO samples, which increases with increasing electric field frequency according to the power law with a fractional exponent.

Preparation of w–cu nano-composite powders with high copper content using a chemical co-deposition technique

A novel chemical co-precipitation was used to produce W-70%Cu nanocomposite powders with coating structure. The precursors consistingofCuC2O4·xH2O and WO3·2H2O were first synthesizedusing copper nitrate, ammoniummetatungstate(AMT) and oxalicacid as the raw materials at 80 °C for 1.5 h when the concentrations of the reactants were 0.8 mol/L and the hydrogen ion concentration was 1.2 mol/L. The precursors were calcined to produce the powders with different phase componentsandmicrostructureatvarious temperatures.The CuWO4 and CuO nano-powders were obtained at 300 °C, which is colder than the traditional reaction temperature (1000 °C) of CuO + WO3 = CuWO4. However, the cubic Cu2Oand Cu2WO4 could beformed when the calcining temperature was 600 °C. The hydrogen reduction results show that the calcined powder is reduced to obtain W-Cu composite powder at 750 °C and 800 °C. In reduction process, volatile WO2(OH)2 through chemical vapor transport(CVT) continuously spreads to the copper surface and is reduced to form W and the coated particle is eventually formed. This particle is Cu particle coated by W phase and the interface between W and Cu phases is semi-coherent. It is found that the average particle size of the reduced powder is 30–50 nm observed by TEM images.

Effect of ultrasonic treatment of the mechanically mixed nanosized CuO–MgO solids on their catalytic properties in the CO oxidation

ABSTRACTThe ultrasonic and the combined ultrasonic/mechanochemical treatments were used for the 1% СuO–MgO catalyst preparation by a simple mechanical mixing of the CuO nanopowder with MgO. Results of the XRD and TEM studies show that the ultrasonic treatment significantly increases the CuO nanoparticle size. The CO oxidation study reveals that the impact of the force treatments caused by the ultrasonic and the combined ultrasonic/mechanochemical activation leads to the catalyst deactivation due to the CuO nanoparticles agglomeration.

Experimental investigation of transparent parabolic trough collector based on gas-phase nanofluid

An experimental study on new high temperature parabolic trough collector (PTC), with transparent receiver tube, based on gas-phase nanofluid, has been carried out for the first time in this work. Two-axes solar tracking PTC, with 4m2 reflecting surface has been realized. Besides, two coaxial quartz tubes, with vacuum in the inner space were used as receiver pipe, with air-dispersed CuO nano-powders as working fluid. The aim of this work was to investigate the technological issues related to the use of gas-based nanofluid coupled with transparent quartz receiver and to evaluate the performance of the first prototype, comparing numerical and experimental results. The experimental campaign highlighted a critical issue related to nanopowder deposition within the receiver pipe, due to humidity. Moreover, in a day of measurement, the fluid temperature higher than 145°C has been maintained for about 10h, reaching a maximum value of 180°C, with a mean efficiency of about 65%.