Letteratura scientifica selezionata sul tema "CuO-Cu₂O/ZnO"

The polyvinyl alcohol-chitosan-ZnO/CuO nanoparticles film was researched. Synthesis, characterization, and its biological evaluation as an antibacterial of Staphylococcus aureus were the aims of this research. The biosynthesis of ZnO, CuO, and ZnO/CuO nanoparticles was done using the biological method. The polyvinyl alcohol-chitosan-ZnO/CuO nanoparticles film was synthesized using the casting method. All the products were characterized by FTIR spectroscopy, X-ray diffraction, and Scanning Electron Microscope (SEM). Polyvinyl alcohol-chitosan-ZnO/CuO nanoparticles film as a paper disk for the evaluation as an antibacterial agent through the agar disk diffusion method. The absorption bands of ZnO, CuO, and ZnO/CuO nanoparticles can be observed at 318, 274, and 252 nm, respectively. The peaks at wavenumbers 433-673 and 619 cm-1 were Zn-O and Cu-O groups, respectively. The Zn-O and Cu-O groups at ZnO/CuO nanoparticles can be observed at 474 and 619 cm-1. The appearance of Zn-O and Cu-O groups at film PVA-chitosan-ZnO/CuO nanoparticles indicates the wavenumber between 433 and 673 cm-1. The physical structure of ZnO, CuO, and ZnO/CuO nanoparticles is crystalline form. The crystallite size of ZnO, CuO, and ZnO/CuO nanoparticles was estimated at 1.0572, 6.6315, and 2.3333 nm respectively. The physical structure of film PVA-chitosan-ZnO/CuO nanoparticles is amorphous. The surface morphology of films C, D, and E was affected by the addition of chitosan and ZnO/CuO nanoparticles. The film of PVA-chitosan-ZnO/CuO nanoparticles (C, D and E) can act as an antibaterial agent of Staphylococcus aureus.The inhibition zone of film D is higher than A, B, C, and E.

The film of chitosan- ZnO/CuO nanoparticles was synthesized. This study were the synthesis and characterization of the chitosan-ZnO/CuO nanoparticles film and its effect as an antibacterial of Escherichia coli. The ZnO, CuO, and ZnO/CuO were biosynthesized by biological method and for the synthesis of the chitosan-ZnO/CuO nanoparticles film, the casting method was adopted. The product was analyzed by FTIR spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscope (SEM), respectively. The product of chitosan-ZnO/CuO nanoparticles film as paper disk and agar disk diffusion method was selected to study an antibacterial agent of this product. The Zn-O or Cu-O group was observed at a peak between 468-675 cm−1 for ZnO and 503 and 619 cm−1 for CuO nanoparticles, respectively. ZnO, CuO, and ZnO/CuO nanoparticles are in the crystalline form and it has a crystallite size of 13.21, 13.21, and 11.49 nm respectively. After interacting with chitosan, the metal nanoparticles such as ZnO, CuO, and ZnO/CuO nanoparticles can change the crystalline form of chitosan to be amorphous form. The addition of ZnO, CuO, and ZnO/CuO nanoparticles in the chitosan will change the surface morphology of chitosan. Chitosan-ZnO/CuO nanoparticles film can inhibit the growth of Escherichia coli bacteria.

Current-Voltage Characteristics of solar cells p-n junction ZnO and TiO₂ parallel in the Cu₂O layer has been determined using solar irradiation. Metal oxide has been used as a semiconductor material, such as ZnO and TiO₂ is an n-type semiconductor. The material has a gap energy of 3.37 eV and 3.2 eV. Thermal oxidation is applied to commercial Cu plates for 60 minutes to produce Cu₂O layers as p-type semiconductors. The process varies in temperature, namely 300, 400, and 500 °C. The process of thermal oxidation on Cu plates at a temperature of 300 °C increases the impurity in the Cu₂O layer. The impurity layer is CuO. Then the CuO layer formed decreases with increasing temperature thermal oxidation. CuO layer increases the efficiency of solar cells p-n junction TiO₂-ZnO parallel in the layer Cu₂O. The results of measurements with sunlight showed that the TiO₂-ZnO/Cu₂O (300) samples had the highest solar cell efficiency, which was 0.28 %.

A protective CuO layer on the Cu₂O quantum dots was prepared by simply heat-treating the Cu₂O/ZnO hetero-nanorod arrays in ambient air, which enhances the photovoltaic stability.

Compared to conventional metal oxide nanoparticles, metal oxide nanocomposites have demonstrated significantly enhanced efficiency in various applications. In this study, we aimed to synthesize zinc oxide–copper oxide nanocomposites (ZnO-CuO NCs) using a green synthesis approach. The synthesis involved mixing 4 g of Zn(NO3)2·6H2O with different concentrations of mangosteen (G. mangostana) leaf extract (0.02, 0.03, 0.04 and 0.05 g/mL) and 2 or 4 g of Cu(NO3)2·3H2O, followed by calcination at temperatures of 300, 400 and 500 °C. The synthesized ZnO-CuO NCs were characterized using various techniques, including a UV-Visible spectrometer (UV-Vis), photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis and Field Emission Scanning Electron Microscope (FE-SEM) with an Energy Dispersive X-ray (EDX) analyzer. Based on the results of this study, the optical, structural and morphological properties of ZnO-CuO NCs were found to be influenced by the concentration of the mangosteen leaf extract, the calcination temperature and the amount of Cu(NO3)2·3H2O used. Among the tested conditions, ZnO-CuO NCs derived from 0.05 g/mL of mangosteen leaf extract, 4 g of Zn(NO3)2·6H2O and 2 g of Cu(NO3)2·3H2O, calcinated at 500 °C exhibited the following characteristics: the lowest energy bandgap (2.57 eV), well-defined Zn-O and Cu-O bands, the smallest particle size of 39.10 nm with highest surface area-to-volume ratio and crystalline size of 18.17 nm. In conclusion, we successfully synthesized ZnO-CuO NCs using a green synthesis approach with mangosteen leaf extract. The properties of the nanocomposites were significantly influenced by the concentration of the plant extract, the calcination temperature and the amount of precursor used. These findings provide valuable insights for researchers seeking innovative methods for the production and utilization of nanocomposite materials.

CuO/ZnO composites are synthesized using a simple mechanochemical combustion method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) are used to characterize the prepared oxides. X-ray diffraction reveals that the prepared CuO/ZnO exhibit a wurtzite ZnO crystal structure and the composites are composed of CuO and ZnO. The strong peaks of the Cu, Zn, and O elements are exhibited in the EDX spectrum. The FTIR spectra appear at around 3385 cm−1 and 1637 cm−1, caused by O–H stretching, and 400 cm−1 to 590 cm−1, ascribable to Zn–O stretching. The photocatalytic performances of CuO/ZnO nanocomposites are investigated for the degradation of methylene blue (MB) aqueous solution in direct solar irradiation. The degradation value of MB with 5 wt % CuO/ZnO is measured to be 98%, after 2 h of solar irradiation. The reactive •O2− and •OH radicals play important roles in the photodegradation of MB. Mineralization of MB is around 91% under sunlight irradiation within 7 h. The photodegradation treatment for the textile wastewater using sunlight is an easy technique—simply handled, and economical. Therefore, the solar photodegradation technique may be a very effective method for the treatment of wastewater instead of photodegradation with the artificial and expensive Hg-Xe lamp.

CuO/ZnO/Al2O3 catalysts are commonly used for the methanol steam reforming reaction. The oxalate precursor of CuO/ZnO/Al2O3 catalysts were prepared via the co-precipitation method using oxalic acid as the precipitator, deionized water and ethanol as the solvent, and microwave radiation and water baths as aging heating methods, respectively. This suggests that ethanol selects the crystalline phase composition of oxalate precursors and limits their growth. Microwave irradiation prompted the isomorphous substitution between Cu2+ of CuC2O4 and Zn2+ of ZnC2O4 in the mother liquid; Zn2+ in ZnC2O4·xH2O was substituted with Cu2+ in CuC2O4, forming the master phase (Cu,Zn)C2O4 in the precursor. Moreover, the solid solution Cu-O-Zn formed after calcination, which exhibited nano-fibriform morphology. It has the characteristics of small CuO grains, a large surface area, and strong synergistic effects between CuO and ZnO, which is conducive to improving the catalytic performance of methanol steam reforming. The conversion rate of methanol reached 91.2%, the space time yield of H2 reached 516.7 mL·g−1·h−1, and the selectivity of CO was only 0.29%.

The process of fine-crystal CuO reduction by successive small portions of H 2 was studied through isothermal calorimetric, kinetic, adsorption-desorption, and stoichiometric measurements at 293-520 K and H 2 pressures up to 100 Pa under conditions when equilibrium within the solid was achieved at any instant. The CuO studied was in the form of the component of the CuO-ZnO-Al 2 O 3 system. The stoichiometry of the copper component reduced corresponded to Cu 4· OH 2.

The structural changes during activation by temperature-programmed reduction of a Cu/ZnO catalyst for methanol synthesis have been studied by severalin situtechniques. The catalyst is prepared by coprecipitation and contains 4.76 wt% Cu, which forms a substitutional solid solution with ZnO as determined by resonant X-ray diffraction.In situresonant X-ray diffraction reveals that the Cu atoms are extracted from the solid solution by the reduction procedure, forming metallic Cu crystallites. Cu is redispersed in bulk or surface Zn lattice sites upon oxidation by heating in air. The results are confirmed byin situelectron energy loss spectroscopy andin situresonant small-angle X-ray scattering. The average Cu particle size in the reduced catalyst as determined by the latter technique is ∼27 Å. The observed structural behaviour may have important implications for catalyst design and operation. More than one type of Cu particle with different origins may be present in Cu/ZnO catalysts with Cu loadings higher than the solubility limit of Cu in ZnO: particles formed by extraction of Cu from the (Zn,Cu)O solid solution and particles formed by reduction of CuO primary particles. The former type is highly dispersed and in intimate contact with the surface of the host ZnO particles. The possibility of re-forming the (Zn,Cu)O solid solution by oxidation may provide a means of redispersing Cu in a deactivated catalyst.

La croissance rapide de la population ainsi que l'industrialisation ont suscité des inquiétudes majeures quant à la disponibilité de l'énergie et à la pollution de l'environnement. La résolution de ces problèmes est au cœur de nombreuses recherches à l'échelle mondiale. L'énergie solaire, en tant que source d'énergie propre et pratiquement inépuisable, devrait être efficacement exploitée, notamment via des processus photocatalytiques, pour améliorer la dépollution environnementale. Les nanomatériaux hybrides, tels que ZnO/métal noble et ZnO/oxydes métalliques, se positionnent comme des candidats prometteurs pour atteindre ces objectifs car ils absorbent efficacement la lumière visible et permettent une séparation efficace des porteurs de charge. Ce mémoire est consacré au développement de nouveaux photocatalyseurs hétérostructurés pour la dégradation des polluants organiques. L'étude a exploré deux voies novatrices de synthèse de ZnO associé soit à des nanoparticules d'argent métallique soit à des oxydes de cuivre. Dans la première partie de cette mémoire, un procédé a été développé pour préparer des particules de ZnO d'environ 87 nm associées à des nanoparticules d'argent d'une taille moyenne de 2.7 nm. Cette stratégie met en œuvre la synthèse d'hydroxydes doubles lamellaires de zinc dopés à l'argent, suivie de la photodéposition des ions Ag+ en Ag(0), et enfin, la conversion par thermolyse de l'hydroxyde double lamellaire en oxyde de zinc. Dans la deuxième partie de la thèse, la photodéposition de nanoparticules de CuO-Cu₂O à la surface de ZnO a permis le développement d’hétérostructures avec une jonction p-n entre CuO-Cu₂O et ZnO. Les nouvelles méthodes de synthèse de catalyseurs hétérostructurés développées dans le cadre de cette thèse ont permis le développement de matériaux photocatalytiquement actifs pour la dégradation de polluants persistants en milieux aqueux. En termes de stabilité, ces catalyseurs peuvent être utilisés sur plusieurs cycles de dégradation sans perte notable d'efficacité. Le projet comporte également l'étude des différents paramètres expérimentaux afin d'optimiser les propriétés structurales, électroniques, optiques et photocatalytiques de ces matériaux
The fast growth of the population and industrialization have produced major concerns regarding energy availability and environmental pollution. Addressing these issues is at the forefront of global research. Solar energy, as a clean and almost infinite source, can be effectively harnessed through photocatalytic processes to contribute to environmental remediation. Hybrid nanomaterials, such as ZnO/noble metal and ZnO/metal oxides, emerge as promising candidates to achieve these goals due to their enhanced light absorption capability and excellent charge carrier separation. This thesis is dedicated to the development of new hybrid photocatalysts designed for the degradation of organic pollutants. The study explores two innovative synthesis pathways of ZnO, combined with photodeposited nanoparticles of metallic silver or copper oxide, onto ZnO. In the first part of the study, a solvothermal method was developed to prepare ZnO particles of approximately 87 nm associated with silver nanoparticles with an average size of 2.7 nm. This strategy involves the synthesis of silver-doped zinc double-layered hydroxides, followed by the photodeposition of Ag+ ions into Ag(0), and ultimately, the conversion through thermolysis of the double-layered hydroxide into ZnO. In the second part, the preparation via an environmentally friendly and easy photodeposition method was used to create heterostructured photocatalysts featuring a p-n junction between CuO-Cu₂O and ZnO. The novel synthesis methods for ZnO-based heterostructured catalysts developed in the framework of this thesis have led to the creation of nanohybrid materials exhibiting high efficiency in degrading persistent pollutants in aqueous environments. In terms of stability, these hybrid photocatalysts can be used over multiple degradation cycles without a significant loss of effectiveness. The project also involves the study of various experimental parameters to optimize the structural, electronic, and optical properties of the photocatalysts