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Since semiconductor-based photocatalysis uses solar energy as a free and sustainable energy source and inoffensive photocatalysts, it has been found to be a promising green approach to eliminating dyes, antibiotics, and other pharmaceuticals from water that has been contaminated. In this study, a distinctive magnetic separable Fe3O4-ZnO:V photocatalyst is reported. ZnO:V semiconductors have been produced by seed-assisted growth over preformed magnetite to develop Fe3O4-ZnO:V nanocomposites. The results indicated nanocomposites with the structure of Fe3O4, ZnO:V, according to the findings of the XRD, XPS, and HRTEM investigations. Additionally, magnetic studies revealed at room temperature, the nanocomposite exhibited superparamagnetic properties. Electrochemical Impedance Spectroscopy (EIS) was employed to characterize the ability of the Fe3O4-ZnO:V nanocomposites to transfer electrons. Furthermore, the impact of dopant on optical characteristics was evaluated. When exposed to rhodamine B (RhB), all the samples exhibited photocatalytic activity. Through the use of an ESR experiment and the spin-trapping technique, the existence of reactive oxygen species (ROS) at the solid–liquid interface was demonstrated, and their impact on the samples' photocatalytic activity was highlighted. After recycling, XRD, XPS, and SEM were performed to illustrate the stability of the material. The impact of V doping on the morphologic, structural, and compositional properties of magnetically separable Fe3O4-ZnO:V composite nanoparticles for photocatalytic applications is the innovative aspect of our work. [ABSTRACT FROM AUTHOR]

The hydrodesulphurization of a model component and equimolar ternary mixture of thiophene, 2-ethylthiophene and benzothiophene over sulphided CoMo/γ-Al2O3 and CoMo/γ-Al2O3-Nb2O5 catalysts were investigated in a fixed bed flow reactor. The catalysts were prepared by incipient wetness impregnation method and characterized by textural characteristics, total acidity and chemical species present on the catalysts surface. The characterization results showed that both CoMo/γ-Al2O3-Nb2O5 and sulphided CoMo/γ-Al2O3 catalysts exhibit a mesoporous structure with cylindrical pores open at both ends, evidenced by the IV type adsorption–desorption isotherm with a H1 hysteresis loop and have an average pore diameter between 3 and 4 nm. The chemical species present on the catalysts surface evaluated by XPS indicated that Co2+ and Mo4+ species are present in the sulfide form on both catalysts surfaces. In addition, there are also found oxidic species arising from incomplete reduction and sulphidation. The presence of niobium oxide in the catalytic support had a positive effect in leading to higher specific surface area (170 m2/g) and total acidity (0.421 meq/g) compared with CoMo/γ-Al2O3 catalyst (140 m2/g and 0.283 meq/g) respectively. The evaluation results from the hydrodesulfurization showed that CoMo/γ-Al2O3-Nb2O5 catalyst had a higher activity in hydrodesulphurization process of thiophene, 2-ethylthiophene and benzothiophene. The CoMo/γ-Al2O3-Nb2O5 catalyst eliminated sulfur from the single component feed (corresponding to 2380 ppm S) and reduced below 10 ppm, for the feed consisting in the equimolar ternary mixture of thiophene, 2-ethylthiophene and benzothiophene (2380 ppm S). The reactivity of thiophen compounds was reduced due to competitive adsorption. It was observed that benzothiophene inhibits the transformation of thiophene and 2-ethylthiophene. A mutual inhibition effect between sulfur compounds was also observed when thiophene, 2-ethylthiophene and benzothiophene were combined and tested over the CoMo/γ-Al2O3 catalyst. The inhibition effect had a lower intensity by introducing Nb2O5 in the catalyst support. [ABSTRACT FROM AUTHOR]

The rhenium effect on the performance of CoMoNi/γ-Al2O3 catalyst was studied in thiophene hydrodesulphurization. The unsulfided and freshly sulfided catalysts were characterized by N2 adsorption-desorption, IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and total acidity. The effects of reaction temperature, pressure, and liquid hourly space velocity (LHSV) on thiophene HDS performance shown that the activity of the CoMoNiRe/γ-Al2O3 catalyst for thiophene HDS was superior to that of the CoMoNi/γ-Al2O catalyst, which was mainly ascribed to the higher acidic functional groups. Based on Langmuir- Hinshelwood approach, a kinetic model for thiophene HDS over both catalysts have been developed. In this respect, two mechanisms have been considered, one hypothesizing that hydrogen is adsorbed on different active centers than thiophene (two-centers mechanism) and the other considering one type of active centers. Based on statistical reasons, the kinetic model considering two types of active centers proved to be more adequate in representing the experimental results. [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]

SnO2–TiO2 nanocomposites are prepared by growing TiO2 nanoparticles onto the preformed SnO2 nanoparticles. The SnO2 core nanoparticles ware obtained in the presence of two different surfactants, namely hexadecyltrimethyl ammonium bromide and polyethylene glycol 600 (PEG600), by chemical precipitation followed by a thermal treatment at 500 °C. The TiO2 was obtained directly on modified SnO2 nanoparticles by a sol–gel process. A sample without surfactants was prepared in the same conditions. The processes involved during annealing of precursors were revealed by TGA-FTIR. The crystalline and mesoporous structures of samples were evidenced by XRD, HRTEM and by N2 adsorption–desorption isotherms. XPS investigations highlighted the interface modifications due to the presence of cationic or anionic moieties resulted from the thermal decomposition of surfactants. Combined UPS and UV–Vis measurements allowed the determination of the oxidation energies, band gaps and energy bands alignment of nanocomposites. The photocatalytic activity based on reactive oxygen species (ROS) generation was studied toward degradation of RhB under visible-light irradiation and by the use of EPR coupled with spin-trapping technique. It was found that the generated ROS are only of ·OH type and, this specific process, is analyzed in terms of energy bands alignment. [ABSTRACT FROM AUTHOR]

Detailed theoretical and experimental investigations on the electronic and magnetic properties of the Heusler compounds Mn 2-x Co x VAl with L2 1 structure are presented. The samples have been examined by X-ray diffraction, magnetization measurements and X-ray photoemission. The magnetic measurements show that the Curie temperatures decrease with Co content, ranging between 771 K (x = 0) and 289 K (x = 1), while the magnetization of the samples follows the Slater-Pauling rule. Additionally, electronic band structure calculations using the Korringa-Kohn-Rostoker (KKR) Greens function method have been performed. The evolution of the half-metallic character with the Co content x in the Mn 2-x Co x VAl alloys is discussed based on the density of states (DOS) calculations. The influence of the Co doping on the individual magnetic moments of the Mn and V has been evidenced. Also, the small individual spin moments of Mn and V determined by theoretical calculations in MnCoVAl (x = 1) are confirmed by the Mn 3s and V 3s core level analysis of the X-ray photoemission spectroscopy investigations. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 –ZnS:Mn nanocomposites were prepared by two combined chemical precipitation routes and further characterized to prove the formation of composite structure. The formation mechanism was discussed according to sequential steps of the composite formation. The crystalline structure, morphology and magnetic properties of nanocomposites were identified by XRD, TEM-HRTEM and VSM analyses respectively. The presence of ZnS:Mn shell on Fe 3 O 4 surface was confirmed by XPS, EDX and EPR. The potential cytotoxicity of Fe 3 O 4 –ZnS:Mnx% nanocomposites has been investigated using human skin melanoma (A375) and normal human keratinocytes (HaCaT) cell lines. The cellular uptake on human skin melanoma (A375) was evidenced by CLFM and revealed that Fe 3 O 4 –ZnS:Mnx% nanocomposites penetrated the cells through endocytosis, in a concentration dependent manner. Hyperthermia measurements evidenced that Fe 3 O 4 –ZnS:Mnx% nanocomposites are adequate for magnetic hyperthermia applications. Except the latest case the Fe 3 O 4 –ZnS:Mnx% platforms are safe to use for biomedical applications as they show toxicity starting only from high concentration. [Display omitted] • Fe 3 O 4 –ZnS:Mnx% nanocomposites were prepared in two combined synthesis methods. • The formation mechanism are revealed. • The core-shell architecture was highlighted by XPS depth profile analysis. • Specific structure-magnetic properties are evidenced. • In vitro cytotoxicity and cellular uptake are tested. [ABSTRACT FROM AUTHOR]

The Oxygen Evolution Reaction (OER) is crucial in various processes such as hydrogen production via water splitting. Several electrocatalysts, including metal oxides, have been evaluated to enhance the reaction efficiency. Zeolitic Imidazolate Framework-67 (ZIF-67) has been employed as a precursor to produce Co3O4, showing high OER activity. Additionally, the formation of composites with carbon-based materials improves the activity of these materials. Thus, this work focuses on synthesizing ZIF-67 and commercial activated carbon (AC) composites, which were used as precursors to obtain Co3O4/C electrocatalysts by calculating ZIF-67/CX (X = 10, 30, and 50, the mass percentage of AC). The obtained materials were thoroughly characterized by employing X-ray powder diffraction (XRD), confirming the cobalt oxide structure with a sphere-like morphology as observed in the TEM images. The presence of oxygen vacancies was confirmed by infrared spectroscopy and EPR measurements. The electrocatalytic performance in the OER was investigated by linear sweep voltammetry (LSV), which revealed an overpotential of 325 mV at 10 mA cm−2 and a Tafel slope value of 65.32 mV dec−1 for Co3O4/C10, superior in activity to several previously reported studies in the literature and electrochemical stability of up to 8 hours. The reduced value of charge transfer resistance, high double-layer capacitance, and the presence of Co3+ ions justify the superior performance of the Co3O4/C10 electrocatalyst. [ABSTRACT FROM AUTHOR]

A Ga3+-substituted spinel magnetite nanoparticles (NPs) with the formula Ga0.9Fe2.1O4 were synthesized using both the one-pot solvothermal decomposition method (TD) and the microwave-assisted heating method (MW). Stable colloidal solutions were obtained by using triethylene glycol, which served as a NPs stabilizer and as a reaction medium in both methods. A narrow size distribution of NPs, below 10 nm, was achieved through selected nucleation and growth. The composition, structure, morphology, and magnetic properties of the NPs were investigated using FTIR spectroscopy, thermal analysis (TA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and magnetic measurements. NPs with the expected spinel structure were obtained in the case of the TD method, while the MW method produced, additionally, an important amount of gallium suboxide. The NPs, especially those prepared by TD, have superparamagnetic behavior with 2.02 μB/f.u. at 300 K and 3.06 μB/f.u. at 4.2 K. For the MW sample these values are 0.5 μB/f.u. and 0.6 μB/f.u. at 300 K and 4.2 K, respectively. The MW prepared sample contains a secondary phase and very small NPs which affects both the dimensional distribution and the magnetic behavior of NPs. The NPs were tested in vitro on amniotic mesenchymal stem cells. It was shown that the cellular metabolism is active in the presence of Ga0.9Fe2.1O4 NPs and preserves an active biocompatible cytoskeleton. [ABSTRACT FROM AUTHOR]

There is growing interest in the opportunities regarding construction and demolition wastes, such as glass and metal powders, for developing a circular economy and their transformation into new materials. This management and recycling of construction and demolition waste offers environmental benefits and conservation of natural resources. In this paper, new magnetic composite materials were prepared by wet chemical synthesis methods using crushed glasses and iron and steel waste powders as raw materials. The prepared iron–silicate composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis, infrared (IR), ultraviolet–visible, and electron paramagnetic resonance (EPR) spectroscopy, and magnetic measurements. The XRD data confirm the formation of varied crystalline phases of the iron ions. The presence of the Fe3O4 crystalline phase was detected in the composites containing the iron waste powders. The inspection of the SEM micrographs revealed slightly better homogeneity for the composite material containing larger amounts of iron waste and heterogeneous morphology with cracks and random crystallinity for the composite doped with steel waste. By doping with different contents of iron or steel waste powder, structural modifications in the silicate network and the formation of new bands in the IR spectra were evidenced. The UV-Vis spectra were characterized by the absorption peaks for both the tetrahedral and octahedral geometries of the Fe3+ ions and the octahedral coordination of the Fe2+ ions with oxygen anions. The EPR data show resonance lines with g ~2, 4.3, and 6.4, corresponding to the Fe3+ ions. Using hysteresis curves, the superparamagnetic properties of the iron–silicate composites were evidenced. [ABSTRACT FROM AUTHOR]

The rapid development of technological processes in various industrial fields has led to surface water pollution with different organic pollutants, such as dyes, pesticides, and antibiotics. In this context, it is necessary to find modern, environmentally friendly solutions to avoid the hazardous effects on the aquatic environment. The aim of this paper is to improve the photocatalytic performance of zinc oxide (ZnO) nanoparticles by using the plasmonic resonance induced by covering them with gold (Au) nanoparticles. Therefore, we evaluate the charge carriers' behavior in terms of optical properties and reactive oxygen species (ROS) generation. The ZnO-Au nanocomposites were synthesized through a simple chemical protocol in multiple steps. ZnO nanoparticles (NPs) approximately 20 nm in diameter were prepared by chemical precipitation. ZnO-Au nanocomposites were obtained by decorating the ZnO NPs with Au at different molar ratios through a reduction process. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) confirmed the simultaneous presence of hexagonal ZnO and cubic Au phases. The optical investigations evidenced the existence of a band-gap absorption peak of ZnO at 372 nm, as well as a surface plasmonic band of Au nanoparticles at 573 nm. The photocatalytic tests indicated increased photocatalytic degradation of the Rhodamine B (RhB) and oxytetracycline (OTC) pollutants under visible light irradiation in the presence of ZnO-Au nanocomposites (60–85%) compared to ZnO NPs (43%). This behavior can be assigned to the plasmonic resonance and the synergetic effects of the individual constituents in the composite nanostructures. The spin-trapping experiments showed the production of ROS while the nanostructures were in contact with the pollutants. This study introduces new strategies to adjust the efficiency of photocatalytic devices by the combination of two types of nanostructures with synergistic functionalities into one single entity. ZnO-Au nanocomposites can be used as stable photocatalysts with excellent reusability and possible industrial applications. [ABSTRACT FROM AUTHOR]

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]

The research investigated the effect of gold (Au-CM) and silver nanoparticles (Ag-CM) phytoreduced with Cornus mas fruit extract (CM) on a human colorectal adenocarcinoma (DLD-1) cell line. The impact of nanoparticles on the viability of DLD-1 tumor cells and normal cells was evaluated. Oxidative stress and cell death mechanisms (annexin/propidium iodide analysis, caspase-3 and caspase-8 levels, p53, BCL-2, BAX, NFkB expressions) as well as proliferation markers (Ki-67, PCNA and MAPK) were evaluated in tumor cells. The nanoparticles were characterized using UV–Vis spectroscopy and transmission electron microscopy (TEM) and by measuring zeta potential, hydrodynamic diameter and polydispersity index (PDI). Energy dispersive X-ray (EDX) and X-ray powder diffraction (XRD) analyses were also performed. The nanoparticles induced apoptosis and necrosis of DLD-1 cells and reduced cell proliferation, especially Ag-CM, while on normal cells, both nanoparticles maintained their viability up to 80%. Ag-CM and Au-CM increased the expressions of p53 and NFkB in parallel with the downregulation of BCL-2 protein and induced the activation of caspase-8, suggesting the involvement of apoptosis in cell death. Lipid peroxidation triggered by Ag-CM was correlated with tumor cell necrosis rate. Both nanoparticles obtained with phytocompounds from the CM extract protected normal cells and induced the death of DLD-1 tumor cells, especially by apoptosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • CoFe 2 O 4 -ZnO composites with three relative concentrations were prepared. • CoFe 2 O 4 has a degree of inversion of 0.7 with spin-up states above the valence band. • Ferrite proximity induces ferromagnetic coupling of oxygen vacancies (V O) in ZnO. • V O assisted spin-polarized photocatalytic Rhodamine B degradation is produced. In this work, magnetic heterostructures were obtained by the in-situ growth of various ZnO amounts on the preformed CoFe 2 O 4 nanoparticles. The X-ray diffraction characterization shows the presence of both ZnO and CoFe 2 O 4 crystalline phases, and the crystallite size is about 13–14 nm for both components. X-Ray Photoelectron Spectroscopy (XPS) analysis revealed a CoFe 2 O 4 inversion degree of 0.7. The composite samples demonstrated an extended absorption edge into the visible range. The sample's magnetic properties were investigated by vibrating-sample magnetometer (VSM) and correlated with Electron Paramagnetic Resonance (EPR) results. The magnetic behavior was attributed to the combination of CoFe 2 O 4 and ferromagnetic ZnO. The emergence of a ferromagnetic phase within ZnO was elucidated to originate from charge/spin transfer of spin-up polarized states from the CoFe 2 O 4 Fermi level into empty oxygen vacancies of ZnO. High efficiency in Rhodamine B (RhB) degradation under visible light was observed in the prepared composite materials, particularly with an optimal CoFe 2 O 4 -ZnO ratio of 1:5, achieving an 81 % degradation rate within 6 h. The proposed photodegradation mechanism, based on various spectroscopic and magnetic investigations, highlights the role of spin transfer and oxygen vacancies in facilitating reactive oxygen species (ROS) generation for pollutant degradation. [ABSTRACT FROM AUTHOR]

Abstract: Polydopamine coated magnetite nanoparticles are functionalized with azido groups by reaction with 4-azidobutylamine. The resulting nanoparticles allow straight forward Cu-catalyzed “click”-reaction with alkynes. In this way practically interesting functions can be tethered to the nanoparticles as exemplified by introducing biotin, glucose, proline or dansyl. The nanoparticles exhibit superparamagnetic behavior. [Copyright &y& Elsevier]

• Superparamagnetic CoFe 2 O 4 and MnFe 2 O 4 obtained by sol-gel synthesis at 1200 °C. • Crystallite size of ferrites increase with increasing annealing temperature. • Magnetic properties of ferrites increase with increasing annealing temperature. • NiFe 2 O 4 and CuFe 2 O 4 are paramagnetic, while ZnFe 2 O 4 is ferromagnetic at 1200 °C. In this work, the (Co 0.4 Mn 0.6 Fe 2 O 4) δ (SiO 2) 100-δ (δ = 0–100%) nanocomposites were synthesized via a modified sol-gel method followed by annealing at 200, 400, 700 and 1100 °C. The main purpose of this paper is to find a relationship between the nanoparticle structure and morphology and the magnetic parameters at different annealing temperatures and different ferrite contents embedded in the SiO 2 matrix. The powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were used to investigate the structural properties, such as crystalline phases, degree of crystallinity, crystallite size and the formation of chemical bonds, while transmission electron microscopy (TEM) was used to examine the morphological features of nanocomposites. The dependence of saturation and remanent magnetizations, coercivity and magnetic anisotropy on ferrite content embedded in SiO 2 matrix were investigated by vibrating sample magnetometry (VSM). The XRD data showed that the crystallite size increase with increasing annealing temperature and amount of ferrite content embedded in the SiO 2 matrix. The SiO 2 matrix exhibits diamagnetic behavior with a small ferromagnetic fraction, Co 0.4 Mn 0.6 Fe 2 O 4 embedded in SiO 2 matrix presents superparamagnetic-like behavior, while unembedded Co 0.4 Mn 0.6 Fe 2 O 4 a high-quality ferromagnetic type behavior. [ABSTRACT FROM AUTHOR]

Z-scheme heterojunctions comprising Zn x Fe 3-x O 4 @poly(L-DOPA)@ZnO (ZF@PD@ZnO) were synthesized using solvothermal and precipitation techniques. The study aimed to investigate the impact of the poly(L-DOPA) electron transfer mediator on the photocatalytic performance of Zn x Fe 3-x O 4 @ZnO (ZF@ZnO) nanocomposites under visible light irradiation. X-ray diffraction (XRD) and HRTEM analysis confirmed the formation of heterostructures, identifying the crystalline phases of both ZnO and zinc ferrite. BFTEM images revealed a polyhedral shape for all samples, with a tendency toward mild agglomeration. The partial inversion of the zinc ferrite cubic spinel structure was evidenced by FT-IR, XPS, and VSM analyses. Zinc ferrite was found to be ferromagnetic, with cation distributions between tetrahedral (A) and octahedral (B) positions as [ Zn 0.6 2 + Fe 0.4 3 + ] A [ Fe 0.4 2 + Fe 1.6 3 + ]B O 4. The samples exhibited notable photocatalytic activity against Rhodamine B, serving as a model contaminant. Furthermore, the stability and reusability of the samples were examined. Additionally, the study elucidated the photocatalytic mechanism produced by the ternary Z-scheme ZF@PD@ZnO, involving spin-polarized charge carriers. Energy band alignment was evaluated by combining ultraviolet photoelectron spectroscopy (UPS) with UV-Vis spectroscopy. The interplay between band alignment and reactive oxygen species (ROS) generation was discussed in correlation with EPR results. Enhanced ROS generation under visible light illumination, observed in the ZF@PD@ZnO nanocomposite, is mainly due to the addition of the conductive poly(L-DOPA) layer, acting as an electron transfer mediator in the Z-scheme heterojunction, ensuring enhanced charge separation. [Display omitted] • Novel Z-scheme Zn x Fe 3-x O 4 @poly(L-DOPA)@ZnO heterojunctions were prepared. • Poly(L-DOPA) represents an electron transfer mediator. • The samples have superparamagnetic behavior at room temperature. • All samples show photocatalytic activity against RhB under visible irradiation. • The mechanism of photodegradation process was elucidated. [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]

Carbon-based materials are currently at the forefront of materials research due to their outstanding physical, mechanical and electrical properties and exceptional catalytic/electro-catalytic activities. The ability to be dispersed in various polymer matrix leads to a new class of polymer nanocomposites with a wide range of applicability (e.g. food packaging, biosensors, water treatment or drug delivery). The main goal of this study was to provide a facile, rapid, inexpensive way for the green, single-step and large-scale preparation of chitosan/graphene nanomaterial, through electrochemical exfoliation of graphite rods, without the use of any organic solvent. The obtained nanocomposite was characterized from morphological and structural point of view. The X-Ray Diffraction investigation indicates that the obtained material appears as a mixture of few-layer graphene (FLG - 73.75%), multi-layer graphene (MLG - 22.38%) and a small chitosan contribution (3.87%). Furthermore, the applicability of chitosan/graphene-glassy carbon modified electrode for accurate detection and quantification of Sunset Yellow was also reported. As expected, the modified electrode exhibits a wide linear range (2 × 10 −7 - 10 −4  M) and low detection limit (LOD = 6.66 × 10 −8  M; S/N = 3). [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 decomposition of succinate type precursors obtained by a modified sol-gel method using cobalt and iron nitrates, 1,4-butanediol and tetraethylorthosilicate, followed by the formation of single phase cobalt ferrite embedded in the silica matrix by annealing at 400–1100 °C was studied. The thermal analysis indicated the formation temperature of succinate type precursors, while the Fourier transform infrared spectroscopy (FT-IR) data confirmed the formation of the precursors in the pores of silica matrix. The formation of CoFe 2 O 4 was investigated by X-ray diffraction and FT-IR, the size and shape of the nanoparticles by transmission electron microscopy, while the resulted microstructures by scanning electron microscopy. The crystallinity and crystallites size increased with the annealing temperature. The hysteresis loops revealed a direct relationship between annealing temperature and saturation magnetization in constant coercive field. The particle size of ferrite powders is critically dependent on the annealing temperature. [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]

The influence of the CoFe 2 O 4 nanoparticles concentration in silica matrix on the structural and magnetic properties of xCoFe 2 O 4 /(100−x)SiO 2 nanocomposites with x=10, 30, 50, 70 and 90 was studied. Magnetic CoFe 2 O 4 nanoparticles dispersed in silica matrix was obtained by sol-gel method, followed by annealing at 1100 °C. The X-ray diffraction pattern and FT-IR spectra revealed the single spinel ferrite structure for all samples. The FT-IR spectra also suggested the formation of the amorphous silica matrix. The results showed that the increase of cobalt ferrite concentration (x) in the silica matrix leads to high crystallinity, specific surface area and particle size. The magnetic CoFe 2 O 4 nanoparticles have spherical shapes and size in the 6–35 nm range. The Mössbauer measurements were fitted with two Zeeman sextets, indicating that all the samples were completely magnetically ordered. The vibrating sample magnetometer studies showed that the saturation magnetization (Ms) and coercivity (Hc) of the CoFe 2 O 4 nanocrystals embedded in silica matrix possessed a linear relationship with the mean crystallite size. Also, the saturation magnetization of the studied nanocomposites increases with the increase of cobalt ferrite concentration (x) in the silica matrix. [ABSTRACT FROM AUTHOR]

MWCNT decorated with undoped and Cu or Mn-doped TiO 2 nanoparticles were synthesized successfully. PXRD patterns show the diffraction plans specific to MWCNT, anatase, and rutile phases of TiO 2. The ratio between anatase and rutile phases differs from sample to sample. Through EPR spectroscopy, the defect and the valence states of the dopant ions in the TiO 2 lattice were shown and correlated with XPS results. The morphology of the samples was analyzed by SEM and TEM. The photocatalytic activity of the samples was evaluated against RhB aqueous solution under UV irradiation. The sample containing Cu2+ ions has the best photocatalytic performance. The photocatalytic mechanism was explained based on the correlation of structural characteristics, optical properties, ROS species generation, and scavenger experiments. The electrochemical performance of the SPE electrode modified with MWNCT-TiO 2 :Cu towards RhB detection was tested, and the obtained sensitivity is higher than that corresponding to bare SPE. [Display omitted] • MWCNT decorated with undoped and Cu or Mn doped TiO 2 were synthesized. • The doping influence the stabilization of a certain polymorphic phase of TiO 2. • EPR evidenced the defect and valence states of dopant ions from TiO 2 lattice. • All samples show photocatalytic activity Cu doping ensuring the best performances. • The Cu doped sample works as sensor material for electrochemical RhB detection. [ABSTRACT FROM AUTHOR]

Co x Fe 3− x O 4 ( x =0.5–2.5) magnetic nanoparticles were synthesized via redox reaction between cobalt nitrate, iron nitrate and 1-4-butanediol using five Co/Fe molar ratios, followed by calcination at 1000 °C. Single phase nanoscaled cobalt ferrite was obtained at x =1.0 and at slight Co excess ( x =1.5), while at high Co/Fe molar ratios ( x =2.0 and x =2.5) the prevailing phase was CoO accompanied by CoFe 2 O 4 traces. The highest values of coercive field and saturation magnetization were obtained for the sample at x =1.0, while the lowest values were obtained in the sample with the highest Co excess ( x =2.5). The results indicated that the used synthesis route was suitable for the synthesis of cobalt ferrite with moderate saturation magnetization and high coercive field values. [ABSTRACT FROM AUTHOR]

Four N-doped graphene materials with a nitrogen content ranging from 8.34 to 13.1 wt.% are prepared by the ball milling method. This method represents an eco-friendly mechanochemical process that can be easily adapted for industrial-scale productivity and allows both the exfoliation of graphite and the synthesis of large quantities of functionalized graphene. These materials are characterized by transmission and scanning electron microscopy, thermogravimetry measurements, X-ray powder diffraction, X-ray photoelectron and Raman spectroscopy, and then, are tested towards the oxygen reduction reaction by cyclic voltammetry and rotating disk electrode methods. Their responses towards ORR are analysed in correlation with their properties and use for the best ORR catalyst identification. However, even though the mechanochemical procedure and the characterization techniques are clean and green methods (i.e., water is the only solvent used for these syntheses and investigations), they are time consuming and, generally, a low number of materials can be prepared, characterized and tested. In order to eliminate some of these limitations, the use of regression learner and reverse engineering methods are proposed for facilitating the optimization of the synthesis conditions and the materials' design. Thus, the machine learning algorithms are applied to data containing the synthesis parameters, the results obtained from different characterization techniques and the materials response towards ORR to quickly provide predictions that allow the best synthesis conditions or the best electrocatalysts' identification. [ABSTRACT FROM AUTHOR]

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of organic pollutants has been established as one of the most effective and affordable technique to solve the environmental contamination issues. The present work was focused on the development of Cu doped ZnO-MWCNT nanocomposites designated for photodegradation of three water organic pollutants namely rhodamine (RhB) dye, phenol and oxytetracycline (OTC) antibiotic. The nanocomposite samples, with MWCNTs: ZnOCu weight ratios of 1:1, 1:3 and 1:5 were prepared and characterized using modern techniques. XRD revealed the presence of both MWCNT and ZnO crystalline phases in composites. The specific bands of MWCNT and ZnO composite components were highlighted by FT-IR. EPR and XPS spectroscopy showed the presence of Cu2+ ions inside the ZnO lattice. SEM and TEM images provided evidence of the attaching and distribution along the nanotubes of Cu doped ZnO nanoparticles with spherical form and diameter around 20 nm. The energy band gap of nanocomposites decreased with the increase of MWCNT amount. The PL emissions gradually quenched by increasing MWCNT content due to electron-hole recombination delays, which favors photocatalytic activity. Evaluation of nanocomposites as photocatalysts for degradation of the three types of pollutant solutions under visible irradiation demonstrated that all samples possessed photocatalytic activity. The best photocatalytic performance was acquired using MWCNT-ZnOCu-3 sample with degradation rates of 76%, 55% and 91% for RhB, OTC and phenol solutions, respectively. The mechanism of photocatalytic activity was elucidated based on the scavenger experiments, reactive oxygen species involved in this process and in correlation with energy bands alignment and gap states. The degree of mineralization of pollutant solutions obtained via total organic carbon analysis was evaluated. • Cu doped ZnO-MWCNT was prepared and characterized with modern techniques. • The attaching of Cu doped ZnO nanoparticles on MWCNT was confirmed by SEM and TEM. • The samples are able to degrade different types of pollutants under visible light. • The mechanism of photocatalytic activity was elucidated. • TOC analysis confirms that RhB molecules break into inorganic species. [ABSTRACT FROM AUTHOR]

In order to limit the photogenerated charges recombination and to ensure an efficient photocatalytic degradation of RhB pollutant, a MWCNT-ZnO:Fe composite material was designed. Fe doped ZnO Nps grouped into quasi-spherical structures of about 100–250 nm were grown in situ on MWCNTs using sol-gel method. The XPS and UPS analysis allowed the identification of both Fe2+ and Fe3+ ionic species at substitutional and surface positions. The substitutional Fe3+ will generate an inverse Burstein-Moss effect and, as a result, the Fermi level is will be pushed down towards the valence band by 0.7, 0.45 and 0.29 eV for 2, 3 and 5% Fe doping respectively. The Fe doped samples show ferromagnetic behavior as determined from both ESR and magnetization measurements. The ferromagnetic order, the inverse Burstein-Moss effect, and the hole capture into the MWCNT valence band favors the charge separation of photogenerated e-h pairs and the reactive oxygen species (ROS) generation in ZnO. The proposed energy bands setup allowed to elucidate both ferromagnetic order formation and the photodegradation mechanism. Thus, an Fe doping degree of 5% ensured, besides the highest magnetization, a 97% photodegradation efficiency and a pollutant mineralization degree of 92%. Image 1 • Fe doped ZnO Nps grouped into quasi-spherical structures were grown in situ on MWCNT. • XPS measurement reveals that Fe2+ and inner/surface Fe3+ ions coexist in samples. • Inner Fe3+ is responsible for ferromagnetism and photogenerated e-h pairs separation. • Surface Fe3+ influence the photodegradation efficiency by O 2 − generation. • The best photocatalytic performance was obtained for MWCNT-ZnO:Fe5% sample (97%). [ABSTRACT FROM AUTHOR]

• CNT-COOH/MnO 2 /Fe 3 O 4 nanocomposite prepared is a new adsorbent. • The adsorption process depends on pH, temperature, time, adsorbent dose, drugs concentration. • High adsorption capacity of ibuprofen and paracetamol was obtained on CNT-COOH/MnO 2 /Fe 3 O 4. The nanocomposite CNT-COOH/MnO 2 /Fe 3 O 4 was synthesized and characterized by different techniques, namely X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis, magnetic measurement, point of zero charge and hydrophobicity index. Analyzes revealed the groups -COOH, MnO 2 and Fe 3 O 4 attached to the carbon nanotubes, the acidic character of the obtained nanocomposite and its stability. The surface area for the obtained nanocomposite was 114.2 m2 g−1. The prepared nanocomposite was used for adsorption of ibuprofen and paracetamol from aqueous solution. Isotherm, kinetic and thermodynamic parameters were determined for predicting the ibuprofen and paracetamol adsorption on synthetized nanocomposite. The equilibrium data obtained from adsorption were well represented by Langmuir model and kinetics data were well fitted by the pseudo-second order model. The maximum adsorption capacity obtained for ibuprofen and paracetamol was 103.093 mg g−1, 80.645 mg g−1 respectively. The thermodynamic analysis showed that the adsorption process for both pollutants was spontaneous and endothermic. The synthetized nanocomposite can be a suitable new absorbent for ibuprofen and paracetamol removal from aqueous solutions due to its high adsorbing capacity and it can be separated by an external magnetic field. [ABSTRACT FROM AUTHOR]

N-doped graphene-ZnO hybrid materials with different N-doped graphene:ZnO wt% ratios (1:10; 1:20; 1:30) were prepared by a simple and inexpensive sol-gel method. The materials denoted NGr-ZnO-1 (1:10), NGr-ZnO-2 (1:20), and NGr-ZnO-3 (1:30) were investigated with advanced techniques and their morpho-structural, photocatalytic, and electrocatalytic properties were reported. Hence, pure N-doped graphene sample contains flakes with the size ranging from hundreds of nanometers to micrometers. In the case of all NGr-ZnO hybrid materials, the flakes appear heavily decorated with ZnO nanoparticles, having a cauliflower-like morphology. The X-ray powder diffraction (XRD) investigation of N-doped graphene sample revealed that it was formed by a mixture of graphene oxide, few-and multi-layer graphene. After the ZnO nanoparticles were attached to graphene, major diffraction peaks corresponding to crystalline planes of ZnO were seen. The qualitative and quantitative compositions of the samples were further evidenced by X-ray photoelectron spectroscopy (XPS). In addition, UV photoelectron spectroscopy (UPS) spectra allowed the determination of the ionization energy and valence band maxima. The energy band alignment of the hybrid materials was established by combining UV–Vis with UPS results. A high photocatalytic activity of NGr-ZnO samples against rhodamine B solution was observed. The associated reactive oxygen species (ROS) generation was monitored by electron paramagnetic resonance (EPR)-spin trapping technique. In accordance with bands alignment and identification of radical species, the photocatalytic mechanism was elucidated. [ABSTRACT FROM AUTHOR]