Structural investigations of the xTeO-(1-x)GeO (x=0, 0.2, 0.4, 0.6, 0.8 and 1) tellurite glasses: A composition dependent Raman spectroscopic study

International audienceRaman spectra of xTeO-(1-x)GeO (x=0, 0.2, 0.4, 0.6, 0.8 and 1) germanium tellurite glasses were measured and analyzed in an effort to follow the structural changes caused by mixing two typical glass-formers. Systematic Raman intensity measurements have been performed in an effort to elucidate the composition induced structural changes and a possible mechanism that accounting for these changes was proposed. The network structure of the glass is characterized by TeO trigonal bipyramid mixed with TeO trigonal pyramid units, while GeO tetrahedral units are also present. Changing the GeO content results to conversion of the TeO units to TeO units with a neutral doubly-bridged oxygen atom, while the existence of charged terminal oxygen atoms is questionable. The measured relative Raman intensities are semi quantitatively correlated to the transformation of the TeO trigonal bipyramid into TeO trigonal pyramids

Photocatalysis as an advanced reduction process (ARP): The reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites

TiO2 photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO2 P25 as a precursor material. Based on these nanotubular substrates, TiO2/CoFe2O4 (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (˜100 m2/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process. © 2018 Elsevier B.V