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We describe the generation and properties of TiO2-based macroscopic fibers designed for the photodecomposition of volatile organic compounds (VOC). We made use of a continuous industrially scalable extrusion process employing hybrid sols of amorphous titania nanoparticles, polyvinyl alcohol (PVA), and optionally latex nanoparticles. This process allowed for the continuous generation of hybrid TiO2/latex/PVA or TiO2/PVA macroscopic fibers. Upon thermal treatment in air, we obtained biphasic porous fibers containing the anatase phase of TiO2 with 10-15% of brookite. These fibers, which can be manufactured as several hundred meters of length reels, provide significantly improved phototocatalytic efficiency compared to our previous work. Their efficiency is now comparable to the commercial Quartzel®PCO photocatalyst for gas-phase acetone mineralization. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ceramic membranes were changed into hydrophobic gas/liquid contactors. [•] These membranes were tested for effective and complete CO2 injection. [•] Bubble-free dissolution of CO2 was demonstrated for all membranes. [•] Nano-coated hydrophobic membranes displayed a 10 times higher dissolution rate. [ABSTRACT FROM AUTHOR]

Abstract: Nb3Sn is a superconductor that exhibits higher performances than NbTi alloy currently used in superconducting magnets, regarding both the critical magnetic field and critical current. However, Nb3Sn is an intermetallic compound prepared by thermal treatment, which loses ductility and plasticity once reacted. Since organic materials cannot be used as insulating sheaths and applied before the thermal treatment required for the synthesis of Nb3Sn, a clay mineral-based organic-free sheath was prepared, which can be applied to Nb3Sn magnetic coils prepared by the wind & react method, before the thermal process. This process allows for facile shaping of the superconductor precursor, before reaction, along with the application of the insulating coating, the sintering of this coating being achieved by the thermal treatment required for the synthesis of Nb3Sn. This process has been designed for industrial developments and facile scale-up. The final material is an organic-free ceramic ribbon that can be stored before further use as an insulating sheath of Nb3Sn wires, and electrical and magnetic tests on both the material and a specific demonstrator made with a 20m superconducting reel, demonstrate that this material can be used as an insulating sheath, with no side-effect on superconductor properties. [Copyright &y& Elsevier]

Abstract: We used a new synthesis of TiO2 anatase 6nm nanocrystals prepared at room temperature (Hegazy and Prouzet, 2012 [10]) to explore the influence of different physical-chemical parameters on photocatalysis, and bench-tested the material against two commercial powders made of either pure anatase (Sigma™), or composite anatase–rutile particles (P25 Degussa™). The initial as-synthesised material demonstrates a low photocatalytic activity, which is greatly improved after thermal activation as a result of improved crystallinity without any drastic change in crystal size. The influence of several other parameters was studied, the resulting tests being compared with commercial products. The cumulative improvement provided by these different parameters led finally to a material that exhibits a higher photocatalysis compared to commercial anatase, and similar to the commercial material usually used for reference (P25). This study, which can apply to other titania materials, illustrates how the post-treatment and process adaptation can help to optimise an initial material. [Copyright &y& Elsevier]

TiO2 nanoparticles are a major component in many areas, and especially for dye-sensitized solar cells (DSSC) as a result of their electronic structure that allows them to collect the electrons transferred from the dye molecules after sunlight irradiation, as well as of their semiconducting properties, which provide the surface transport of these electrons up to the collecting electrode. However, for this application or others, the optimization of both structural and electronic properties of titanium oxide is still a challenge because it depends on both crystalline structure and material nano/mesostructure. We report how small (<6 nm) titanium oxide nanoparticles were synthesized by a single step method, with the anatase crystalline phase obtained at room temperature, and an opened nanostructure. A mixture design method was required to identify the precise composition that led to the suitable material. Mesoporous materials made of pure anatase nanocrystals were obtained with the suitable porosity (5 nm pore diameter, 190 m2/g, 0.3 mL/g porous volume) without any surfactant agent. Both the evolution of the crystal size and nature of the phases were studied as a function of heating temperatures ranging from 20 to 800 °C. These materials display a good thermal stability up to 400 °C, in term of crystal size, and up to 700 °C, regarding the crystalline phase. Finally, the study of their semiconducting properties as a function of the crystal size allowed us to confirm the previous theoretical models regarding the crystal size-dependence of band gap and to set the limit of the size quantum confinement effect around 7 nm. The parameters for the synthesis of mesoporous nanocrystalline anatase made of 4 nm nanocrystals were identified via a mixture design method. This surfactant-free room temperature synthesis gives mesoporous materials (5 nm pore size, 190 m2/g, 0.3 mL/g porous volume), which display band gap size quantum confinement, that were tested more specifically for dye-sensitized solar cell applications. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic behavior of molecular magnets-based nanocomposite materials was investigated as a function of the molecular materials’ concentration. These materials, made of transition metal ions connected via cyano-bridging ligands, Co3[Fe(CN)6]2, were synthesized simultaneously with MSU-type mesoporous silica as a confinement matrix. This synergetic synthesis led to Co3[Fe(CN)6]2 nanoparticles of ca. 2–3nm. Their magnetic properties were investigated as a function of their concentration. These analyses, including dc and ac vs temperature, as well as frequency measurements, reveal a superspin-glass like transition at low temperature. The aging and memory effects observed demonstrate that the superspin-glass behavior for nanocomposites containing the lowest amount of nanoparticles is due principally to spin frustration on the surface of the nanoparticles while for the nanocomposites containing the largest amount of nanoparticles, both surface spin-frustration and dipolar interparticle interactions influence the magnetic regime. [Copyright &y& Elsevier]