Search results for "CU2O"

Vibrational Properties of CuO and Cu4O3 from First-Principles Calculations, and Raman and Infrared Spectroscopy

2012

International audience; A combined experimental and theoretical study is reported on the vibrational properties of tenorite CuO and paramelaconite Cu4O3. The optically active modes have been measured by Raman scattering and infrared absorption spectroscopy. First-principles calculations have been carried out with the LDA+U approach to account for strong electron correlation in the copper oxides. The vibrational properties have been computed ab initio using the so-called direct method. Excellent agreement is found between the measured Raman and infrared peak positions and the calculated phonon frequencies at the Brillouin zone center, which allows the assignment of all prominent peaks of the…

Photoelectrochemical characterization of Cu2O-nanowire arrays electrodeposited into anodic alumina membranes

2007

Perfectly aligned nanowire arrays of polycrystalline Cu2O were grown by template-pulsed electrodeposition from a cupric acetate-sodium acetate bath into anodic alumina membranes (AAM). The photoelectrochemical behavior of arrays with different nanowire lengths (0.5 mu m and 2 mu m) was investigated in neutral solution, and the results compared to those pertaining to Cu2O films grown with the same procedure. Although all samples displayed the same indirect bandgap (similar to 1.9 eV), differences were observed both in photocurrent intensity and sign. The latter changed with potential and wavelength in different ways for nanowires and films, revealing a different defect concentration in the t…

Improved Cu2O/AZO Heterojunction by Inserting a Thin ZnO Interlayer Grown by Pulsed Laser Deposition

2019

Cu2O/ZnO:Al (AZO) and Cu2O/ZnO/AZO heterojunctions have been deposited on glass substrates by a unique three-step pulsed laser deposition process. The structural, optical, and electrical properties of the oxide films were investigated before their implementation in the final device. X-ray diffraction analysis indicated that the materials were highly crystallized along the c-axis. All films were highly transparent in the visible region with enhanced electrical properties. Atomic force and scanning electron microscopies showed that the insertion of a ZnO layer between the Cu2O and AZO films in the heterojunction enhanced the average grain size and surface roughness. The heterojunctions exhibi…

Photoelectrochemical Evidence of Cu2O/TiO2 Nanotubes Hetero-Junctions formation and their Physicochemical Characterization

2014

Cu2O/TiO2 nanotubes heterojunctions were fabricated by electrochemical deposition of cuprous oxide on TiO2 nanotubes arrays grown by anodizing. X-ray diffraction and Raman Spectroscopy analysis allows for identification of Cu2O, whose morphological features were studied by Scanning Electron Microscopy as a function of the charge circulated during the electrodeposition step. Photoelectrochemical measurements in aqueous solutions evidenced a red shift of the light absorption threshold of TiO2 nanotubes due to the presence of cuprous oxide even for very low circulated charges, while electrochemical impedance measurements proved a significant reduction of the electrode impedance due the presenc…

Photocatalysis of rhodamine B and methyl orange degradation under solar light on ZnO and Cu2O thin films

2020

We report the photocatalytic properties of ZnO and Cu2O thin films deposited on glass substrates at room temperature by DC sputtering and pulsed laser deposition. The photoactivity of the films was investigated through the degradation of rhodamine B (RhB) and methyl orange (MO) under solar light. In order to select the most suitable film of ZnO for the of RhB and MO degradation, the relationship between the characteristics (e.g. energy levels and defects concentration) of ZnO films and their effectiveness in the photocatalytic yield of RhB and MO been studied, where several films were deposited by using different oxygen partial pressures (PO2: 0.05–1.3 mbar), while Cu2O films were grown und…

Electrochemical fabrication of Cu2O/TiO2 nanotubes junctions with visible light photoactivity

2013

Redshift of absorption threshold of TiO2 Nanotubes due to Cu2O electrodeposition

2013

Bi-2212 and Y123 highly curved single-crystal-like objects: whiskers, bows and ring-like structures

2012

High-temperature superconducting objects of Bi2Sr2CaCu2O8 and Y Ba2Cu3O7 highly curved in the ab-plane, such as curved/kinked whiskers, bows and ring-like structures, were obtained within a solid?liquid?solid (SLS) grass-like growth mechanism. As-grown objects are crystals with three-dimensional epitaxy similar to conventional single crystals: they can be viewed as crystal parts ?cut? from a conventional rectangular crystal. Between our curved objects and conventional crystals, whiskers or thin films there are some differences in the superconducting properties induced only by the shape factors and no new physics is observed. Some details of the growth mechanism are discussed, emphasizing cu…