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The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were evidenced by X-ray diffraction (XRD). X-ray Photoelectron spectroscopy (XPS) revealed the presence of both 2+ and 3+ valence states of Fe ions in a ratio of approximately 0.5. The electron paramagnetic resonance EPR spectroscopy sustained the presence of Fe3+ ions in the ZnO lattice and evidenced oxygen vacancies. Transmission electron microscopy (TEM) images showed the attachment and distribution of Fe-doped ZnO nanoparticles along the nanotubes with a star-like shape. All of the samples exhibited absorption in the UV region, and the absorption edge was shifted toward a higher wavelength after the addition of MWCNT component. The photoluminescence emission spectra showed peaks in the UV and visible region. Visible emissions are a result of the presence of defects or impurity states in the material. All of the samples showed photocatalytic activity against the Rhodamine B (RhB) synthetic solution under UV irradiation. The best performance was obtained using the MWCNT:ZnO-Fe(1:5) nanocomposite samples, which exhibited a 96% degradation efficiency. The mechanism of photocatalytic activity was explained based on the reactive oxygen species generated by the nanocomposites under UV irradiation in correlation with the structural and optical information obtained in this study. [ABSTRACT FROM AUTHOR]

Nanocomposites based on half-metallic FePt (L10) magnetic nanoparticles coated with the semiconducting conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) show a significant reduction in the magnetic coercivity. This study adopts a physical approach based on chemical potential equalization at the interface. The underlying charge/spin transfer mechanism unveils an imbalance: only spin-down polarized electrons are allowed to be transferred from the semiconductor to the half-metal (spin-down) conduction band, while spin-up states remain blocked at the interface. This process determines an excess of spin-up states on the P3HT side, and due to a RKKY mechanism, this effective spin system becomes ferromagnetic polarized. Due to this proximity effect, the conjugate polymer becomes exchange coupled to the hard magnetic FePt (L10) phase, thus reducing the coercivity of the half-metal. These processes make this type of composite suitable for magnetic recording applications. [ABSTRACT FROM AUTHOR]

Composite Fe3O4-SnO2 nanoparticles were synthesized by growing SnO2 nanoparticles on the surface of previously prepared Fe3O4 nanoparticles. First, Fe3O4 nanoparticles were prepared by chemical precipitation of precursors followed by the obtaining of SnO2 nanoparticles by chemical precipitation or sol-gel process. The composite nanoparticle samples were characterized by using X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM) and X-Ray photoelectron Spectroscopy (XPS) techniques. Also, electrochemical behaviour was recorded. The results revealed that by adjusting the composition of components one can control the properties of composite nanoparticles. [ABSTRACT FROM AUTHOR]

SnO2 nanoparticles were successfully synthesized by precipitation method, in the presence of hexadecyltrimethyl ammonium bromide (CTAB) and polyethylene glycol 600 (PEG 600) as surfactants. The obtained SnO2 nanoparticles were characterized by X-ray diffraction (XRD), porosity and surface area measurements (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS). Also, photocatalytic properties toward degradation of Rhodamine B (RhB) were investigated. It was found that morpho-structural properties are influenced by the preparative conditions of doped SnO2 nanoparticles. [ABSTRACT FROM AUTHOR]

SnO2 nanoparticles were successfully synthesized by precipitation method, in the presence of hexadecyltrimethyl ammonium bromide (CTAB) and polyethylene glycol 600 (PEG 600) as surfactants. The obtained SnO2 nanoparticles were characterized by X-ray diffraction (XRD), porosity and surface area measurements (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS). Also, photocatalytic properties toward degradation of Rhodamine B (RhB) were investigated. It was found that morpho-structural properties are influenced by the preparative conditions of doped SnO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Interface modified SnO 2 -TiO 2 composite nanoparticles were produced in two stages: first SnO 2 nanoparticles were prepared by chemical precipitation in the presence of polyvinylpyrrolidone (PVP) and thermally treated at 500 °C then TiO 2 was deposited on top of modified SnO 2 and followed by a final annealing. As a consequence SnO 2 –TiO 2 composite nanoparticles get crystallized while PVP is decomposed into monomer units and other attached smaller molecular fragments. TGA coupled with FT-IR spectroscopy confirmed the presence of monomers and other moieties as a result of PVP thermal fragmentation. The crystalline phases and composition of the two oxides were evidenced by X-ray diffraction, HRTEM and XPS. It was found that specific surface area of the composites increases with the increase in the initial amount of PVP. Also, the oxidation potential of the TiO 2 shell, as determined by UV photoelectron spectroscopy (UPS), significantly decreases as the PVP quantity increase and further modifies the band alignment between SnO 2 and TiO 2 components. Additionally, both XPS and UPS spectra as well as EPR investigations indicate the presence of many localized states inside the band gap of TiO 2. With a moderate PVP content the combined effects of band alignment, gap localized states and porosity make possible an increased number of reactive oxygen species (ROS) generation thus increasing photocatalytic activity against RhB dye solution under visible irradiation. The photocatalytic mechanism was elucidated based on the identification of radical species involved and in accordance with energy bands alignment, gap states, and porosity. Besides water purification by photocatalysis, SnO 2 –TiO 2, as ROS generating heterostructures may be used in applications like antibacterial and antitumoral, deodorizing, air purifying, self-cleaning, gas sensing, as well as in hydrogen production. [ABSTRACT FROM AUTHOR]

In this study, photocatalytic Fe 3 O 4 -TiO 2 : Gd berry-like pseudo-core-shell (BL-PCS) nanoparticles with various Gd doping content for wastewater treatment were prepared. Their characteristics were evaluated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS). The results show that Gd 3 + ions are incorporated in the TiO 2 lattice. A secondary phase of FeTiO 3 was observed for undoped and low Gd doping level, phase which is no longer present for high doping content. By TEM and XPS depth profile analysis it was showed that a BL-PCS structure is formed. All the samples have superparamagnetic behavior. The optimum concentration of Gd dopant which assures the best photocatalytic performance on the RhB degradation under visible light irradiation was obtained. The photocatalytic degradation was examined by varying the operational parameters such as: catalyst amount and irradiation time. The photocatalyst can be easily separated from solution due to its magnetic component and presents a good stability with a minor loss of efficiency after 4 repeated cycles. According to the analysis of the reaction intermediates and final products, a mechanism of photodegradation was proposed. Additionally, electron paramagnetic resonance (EPR) study on the ability of Fe 3 O 4 -TiO 2 : Gd to generate reactive oxygen species was conducted and shows that hydroxyl radical and superoxide anion radical are generated under light irradiation, radicals which are involved in the photocatalytic process. [ABSTRACT FROM AUTHOR]

The present work highlights on efficacy of three types of green synthesized magnetite nanoparticles (Fe3O4 NPs) for the removal of a mixture of seven antibiotics, namely piperacillin (PIP), tazobactam (TAZ), sulfamethoxazole (SUL), tetracycline (TET), trimethoprim (TRI), ampicillin (AMP) and erythromycin (ERY) from aqueous media. Fe3O4 NPs were prepared through an environmentally friendly, facile and economical synthetic route which uses aqueous peel extracts of lemon (Citrus limon), black grapes (Vitis vinifera) and cucumber (Cucumis sativus), and were denoted as Fe3O4(lem), Fe3O4(grp) and Fe3O4(cum), respectively. The magnetic nanoparticles were characterized by XRD, FTIR, SEM, TEM, BET, XPS, and VSM techniques. A Box-Behnken design approach was employed in order to identify the optimum conditions for removal of selected antibiotics. The concentration of antibiotics was determined using high-performance liquid chromatography coupled with diode array detector and mass spectrometer (HPLC-DAD–MS) analysis. The Langmuir, Freundlich and Temkin adsorption isotherm models were used for description of the adsorption equilibrium of studied antibiotics and kinetic studies were conducted. Overall, Fe3O4 NPs synthesized with extracts exhibited high removal (>90%) of studied antibiotics, excepting SUL and TRI, and likewise demonstrated higher efficiency for the purpose of antibiotics removal than Fe3O4 NPs synthesized by a previously reported conventional method. [ABSTRACT FROM AUTHOR]