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In this work, flower-like molybdenum disulfide (MoS2) microspheres were produced with polyethylene glycol (PEG) to form MoS2-PEG. Likewise, gold nanoparticles (AuNPs) were added to form MoS2-PEG/Au to investigate its potential application as a theranostic nanomaterial. These nanomaterials were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoelectron X-ray spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), cyclic voltammetry and impedance spectroscopy. The produced hierarchical MoS2-PEG/Au microstructures showed an average diameter of 400 nm containing distributed gold nanoparticles, with great cellular viability on tumoral and non-tumoral cells. This aspect makes them with multifunctional characteristics with potential application for cancer diagnosis and therapy. Through the complete morphological and physicochemical characterization, it was possible to observe that both MoS2-PEG and MoS2-PEG/Au showed good chemical stability and demonstrated noninterference in the pattern of the cell nucleus, as well. Thus, our results suggest the possible application of these hybrid nanomaterials can be immensely explored for theranostic proposals in biomedicine. [ABSTRACT FROM AUTHOR]

The preparation of titanium dioxide nanoparticles doped with nitrogen for application as a photocatalyst in the decomposition of azo dyes was optimized by factorial planning. Five variables were evaluated and the results showed that the stirring method of the reaction medium, the nitrogen source and the calcination temperature are the determining parameters that affect the photocatalytic activity. With this methodology, it was possible to obtain an optimized photocatalyst (K1) with high surface area and high mineralization efficiency (100%) of the dye Ponceau 4R under solar irradiation. K1, its non-doped version and the worst photocatalyst obtained by the factorial planning (K2) were characterized by several techniques to rationalize the different behaviors. The observed mineralization rate constants under artificial UV-A radiation were in the order of 10−2, 10−4 and 10−3 min−1, respectively, for K1, K2 and the non-doped oxide. As shown by N2 sorption isotherms, the powders exhibited large variations in porosity as well as in the specific surface area, with values ranging from 63.03 m2 g−1 for K1 to 12.82 m2 g−1 for K2. Infrared spectra showed that the calcination of the doped oxides between 300 and 500 °C leads to considerable loss of the nitrogen content, which is corroborated by XPS measurements that also indicate the presence of oxygen vacancies on their surfaces. Nanosecond transient absorption measurements show that the electron–hole half-lifetime in K1 is 870 ns, ca. two times longer than that observed for the other photocatalysts. Additionally, dye degradation studies under solar radiation reveal that K1 is ca. 28% faster than the non-doped TiO2 under similar conditions. This higher photoactivity for K1 is attributed to its extended visible light absorption and the optimized morphological and electronic properties. [ABSTRACT FROM AUTHOR]

Abstract: The optical, electrical and structural properties of SnOare responsible for a large number of technological 2 applications such as gas sensors, optical-electonic devices, varistors and displays. In this paper, we report the preparation of SnO thin films deposited on glass, quartz and silicon substrates by the technique of sol-gel dip-2coating. The films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ellipsometry and Mössbauer spectroscopy. We combine the experimental results with ab initio all-electrons calculations, using the density functional theory within the framework of the full-potential linear augmented plane waves method, in order to extract hyperfine parameters. The results show that the synthesis method is able to produce good quality films and that the theory can be helpful to determine quantities difficult to be measured experimentally. [Copyright &y& Elsevier]

Abstract: TiO2 thin films, employed in dye-sensitized solar cells, were prepared by the sol–gel method or directly by Degussa P25 oxide and their surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of adsorption of the cis-[Ru(dcbH2)2(NCS)2] dye, N3, on the surface of films was investigated. From XPS spectra taken before and after argon-ion sputtering procedure, the surface composition of inner and outer layers of sensitized films was obtained and a preferential etching of Ru peak in relation to the Ti and N ones was identified. The photoelectrochemical parameters were also evaluated and rationalized in terms of the morphological characteristics of the films. [Copyright &y& Elsevier]

Abstract: In the present work, amorphous niobium oxides with 5% (w/w) vanadium or molybdenum isomorphically substituted into the material structure were synthesized. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that vanadium and molybdenum were incorporated into the niobium oxide structure with concomitant changes in the morphologic and catalytic properties. Catalytic studies on the conversion of residual glycerin generated during biodiesel production in the presence of H2O2 showed enhanced efficiency of ether formation with the vanadium-containing material. The NbV/ethanol/glycerin/250°C system was found to convert 80% of glycerin. Experiment-planning studies in conjunction with the analysis of the surface response via gas chromatography–mass spectrometry (GC–MS) aided in the determination of the optimal conditions. The catalytic tests monitored by GC–MS showed the formation a mixture of ethers obtained by the condensation of glycerol. Furthermore, it was observed that the modification of the catalyst directs the formation of larger molecules such as ketone mainly in the catalyst containing vanadium. [Copyright &y& Elsevier]