The optimization of the figure of merit of thermoelectric materials requires the simultaneous control of the material composition and microstructure. Assembly of nanoparticles obtained by a solution route is an attractive bulk fabrication method because size and shape of the nanoparticles can be tuned by variation of the synthesis conditions. Recently, new synthetic pathways were reported among which reducing agent assisted, surfactant free processes. We report here the evaluation of this method for the synthesis of Bi2TexSe3-x alloyed nanoparticles with varying selenium concentrations. X-ray diffraction studies conducted on powder and pellet samples show that two alloyed phases are present in the sample even at low selenium content. The careful study of the position of the diffraction peaks as function of the formulation shows that this behaviour could arise from the difference in reactivity of selenium and tellurium. Moreover, the electrical conductivity of the samples is shown to increase upon selenium addition while the Seebeck coefficient is reduced. Power factor shows an optimum value around 20% selenium content with a large tolerance in composition.

In here we depict the morphogenesis and associated properties of TiO2-based macroscopic fibers designed for the photodecomposition of volatile organic compounds (VOC). We employed a continuous industrially scalable extrusion-based process making the use of hybrid sols of amorphous titania nanoparticles, polyvinyl alcohol (PVA) and occasionally latex nanoparticles. This process allowed for the continuous generation of hybrid TiO2/latex/PVA or TiO2/PVA macroscopic fibers. Upon thermal treatment, biphasic porous fibers are obtained containing the anatase phase of TiO2 with 10-15% of brookite. These fibers, which can be manufactured under several hundred meter of length, are offering significantly improved phototocatalytic efficiency now comparable to the commercial Quartzel®PCO photocatalyst for gas-phase acetone mineralization.

Solution-based fabrication methods have been widely used for depositing uniform functional coatings. These coatings can be utilized in a variety of applications such as optoelectronics, biomedical, and energy. However, such fabrication techniques are not appropriate for directly depositing patterned micro/nano-scale features, which are required in many contact-based applications such as in MEMS.

In this work we propose the direct writing of hydrophobic silica-based sol-gel patterns with sustained functionality and their subsequent tribological characterization. Such an approach may be an advantageous alternative to current lithography-based methods due to the relative ease of processing and low material waste. This investigation involves the abrasive wear and frictional analysis of patterned fluorinated silica sol-gel coatings that are directly printed onto glass substrates with a robotically controlled pneumatic nozzle system. Such work sheds light on the tribological properties of lithography-free processed hydrophobic patterns for applications spanning from micromotors to biomedical fluidic devices.

A PbSe film was grown by chemical bath deposition on a thermally oxidized Si (111) substrate. Morphological change of the PbSe film during sensitization under the oxygen and iodine atmospheres was studied by SEM. The as-grown polycrystalline PbSe film consists of clusters of about 200nm in diameter. By the oxidation treatment for 30 min at 380°C, the clusters became joined together. On the other hand, recrystallization of new PbSe crystals with faceted surfaces occurred during the iodination treatment under an iodine plus nitrogen atmosphere at 380°C for different durations. This morphological change during the sensitization treatment might affect the electro-optical properties of the PbSe film.

We have developed a new method for controlling the size, crystallinity, and polydispersity of 100–2000 nm tetrafluoride phosphor particles. Five polyol-based deep eutectic solvents (DESs) were downselected out of a set of more than 130 candidates. We analyzed their benefits in synthesizing phosphor matrix particles of β-NaYF4, β-NaYbF4, and β-NaGdF4. We produced green (λmax = 540 nm) and blue/UV (λmax = 450 nm) upconverting phosphors in DES using Yb,Er and Yb,Tm codopants, respectively. The blue/UV phosphor reaction was scaled the up to 25 L, yielding nearly 400 g of high-quality, bright photoluminescent, β-phase product under mild conditions. We conclude that polyol-based DES systems offer a uniquely specialized and useful toolkit for phosphor synthesis.

The present work focuses on the polyol-mediated synthesis of pure and Mg-doped ZnO nanoparticles. The synthesized samples were characterized via X-ray diffraction, Fourier transformed infrared spectroscopy, ultraviolet visible spectroscopy and photoluminescence techniques. The Standard Plate Count was used to assess the bactericidal properties of the nanoparticles against E. coli at 1000 ppm and 1500 ppm of concentration. The capacity of the Zn-Mg oxides to generate singlet oxygen (SO) species was also evaluated. X-ray diffraction information evidenced the formation of ZnO-wurtzite; no diffraction peaks corresponding to isolated Mg-phases were detected. The average crystallite size of the Zn-Mg oxide nanocrystals was estimated in the 6nm - 7nm range. Infrared spectroscopy measurements confirmed the formation of the oxide with a Metal-Oxygen band centered on 536 cm-1; other bands associated to the functional groups of polyol by product were also observed. The exciton peak of UV spectrum suggests similarity in the particle size with the dopant addition. The effect of particle composition (i.e. doping level) on the corresponding generation of SO and bactericidal capacity is presented and discussed.

Designing bioactive materials, with controlled metal ion release, exerting significant bioactivity and associated low toxicity for humans, is nowadays one of the most important challenges for the scientific community. In this work, we propose a new material combining the well-known antimicrobial properties of copper nanoparticles (CuNPs) with those of bioactive chitosan (CS), a cheap natural polymer widely exploited for its biodegradability and nontoxicity. Here, we used ultrafast femtosecond laser pulses to finely fragment, via laser ablation, a Cu solid target immersed into aqueous CS solutions. Homogeneously dispersed copper-chitosan (Cu-CS) colloids were obtained by tuning the Cu/CS molar ratios, according to the initial chitosan concentration, as well as other experimental parameters. Cu-CS colloids were characterized by several techniques, like UV-Vis and X-ray Photoelectron spectroscopies (XPS). Transmission Electron Microscopy (TEM) was used to morphologically characterize the novel nanocomposites.