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Seeing the atomic configuration of single organic nanoparticles at a sub-Å spatial resolution by transmission electron microscopy has been so far prevented by the high sensitivity of soft matter to radiation damage. This difficulty is related to the need to irradiate the particle with a total dose of a few electrons/Å2, not compatible with the electron beam density necessary to search the low-contrast nanoparticle, to control its drift, finely adjust the electron-optical conditions and particle orientation, and finally acquire an effective atomic-resolution image. On the other hand, the capability to study individual pristine nanoparticles, such as proteins, active pharmaceutical ingredients, and polymers, with peculiar sensitivity to the variation in the local structure, defects, and strain, would provide advancements in many fields, including materials science, medicine, biology, and pharmacology. Here, we report the direct sub-ångström-resolution imaging at room temperature of pristine unstained crystalline polymer-based nanoparticles. This result is obtained by combining low-dose in-line electron holography and phase-contrast imaging on state-of-the-art equipment, providing an effective tool for the quantitative sub-ångström imaging of soft matter. [ABSTRACT FROM AUTHOR]

Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical-chemical properties and functionalities, are used in disparate technological fields, including photovoltaics, sensing, environmental remediation and energy storage. In this paper, the preparation of thin films consisting of anatase-phase TiO2 nanorods deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique and their characterization in terms of morphology, elemental composition and wettability are presented and discussed. Particular attention is paid to the effects of the laser fluence, varied over a broad range (F = 25, 50, 100 mJ/cm2), and to the role of the capping surfactants bound to the surface of the nanorod precursors. Whereas increasing fluence favored a partial removal of the surface-bound surfactants, a post-growth UV-light-driven photocatalytic treatment of the films was found to be necessary to reduce the incorporated fraction of organics to a further substantial extent. It was noteworthy that, under our experimental conditions, the distinctive surface patterns and roughness that commonly degrade the morphology of films deposited using the MAPLE technique were not observable. This previously unreported experimental evidence was rationalized on the basis of the interaction dynamics between solvent/solute droplets ejected from the laser-irradiated target and the rough surfaces of the growing film. [ABSTRACT FROM AUTHOR]

A dual soft-templating method was developed to produce highly crystalline and mesoporous TiO2-SiO2 nanocomposites. Pluronic F127 as the structure-directing agent and pure cellulose as the surface area modifier were used as the templating media. While Pluronic F127 served as the sacrificing media for generating a mesoporous structure in an acidic pH, cellulose templating helped to increase the specific surface area without affecting the mesoporosity of the TiO2-SiO2 nanostructures. Calcination at elevated temperature removed all the organics and formed pure inorganic TiO2-SiO2 composites as revealed by TGA and FTIR analyses. An optimum amount of SiO2 insertion in the TiO2 matrix increased the thermal stability of the crystalline anatase phase. BET surface area measurement along with low angle XRD revealed the formation of a mesoporous structure in the composites. The photocatalytic activity was evaluated by the degradation of Rhodamine B, Methylene Blue, and 4-Nitrophenol as the model pollutants under solar light irradiation, where the superior photo-degradation activity of Pluronic F127/cellulose templated TiO2-SiO2 was observed compared to pure Pluronic templated composite and commercial Evonik P25 TiO2. The higher photocatalytic activity was achieved due to the higher thermal stability of the nanocrystalline anatase phase, the mesoporosity, and the higher specific surface area. [ABSTRACT FROM AUTHOR]

In this work, an experiment was carried out in order to exploit the physical properties of an electrode structure with nanometric gap to enable the operation of MOX sensors at low temperature independently from the gas sensing properties of the adopted active material. The 100 nm-gap fingers gas sensor array was fabricated by using electron beam and UV optical lithography onto 4″ silicon wafers (guaranteeing high process yield). SnO2 nanoparticles (NPs) synthesized by sol–gel/solvothermal method were trapped between the nanogap electrodes by dielectrophoresis, and scanning electron microscopy and atomic force microscopy surface analysis were used to investigate the semiconducting NPs dispersion between the nanogap fingers. Nanogap SnO2 NPs based-sensor responses to acetone and ethanol in dry air carrier gas at near room temperatures were reported, discussed, and compared with those obtained from 5 μm gap gas sensors (comparable to standard microgap commonly used in commercial sensors) functionalized with the same sensing material. The nanogap sensors exhibited better performance compared to the microgap ones, and larger response to ethanol than to acetone. For the lowest investigated gas concentration (10 ppm), the ethanol response (Rair/Rgas) increased with temperature from 2.56 at 50 °C to 17.91 to 100 °C, respectively from 1.56 to 3.92 for acetone. The best nanogap sensor responses were found at 100 °C with Rair/Rgas ≈ 38 for 150 ppm of ethanol, and Rair/Rgas ≈ 10 for 150 ppm of acetone. The experimental measurements confirmed the adopted theoretical model correlation between the sensor responses and the electrodes separation gap. [ABSTRACT FROM AUTHOR]

Dy- and Tb-doped CeO2-Ni cermets for highly active solid-oxide fuel-cell (SOFC) anodes were fabricated by a one-pot electrodeposition process. Undoped, singly-doped, and co-doped powders were synthesized in an X-ray amorphous state, heat treated in air, and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) at different crystallization stages. In particular, in situ TEM analyses were carried out during heating in an oxygen atmosphere, in order to follow the evolution of structure and morphology and to understand the role of the dopants. The key structural effect of dopants was the inhibition of grain coarsening during heat treatment. Functional tests were carried out with micro-single chamber SOFCs, fed with a CH4/O2 mixture, the anodes of which were prepared with the CeO2-Ni powders synthesized in this study. A correlation was established between the electrocatalytic performance and the morphology of the anodic material, pinpointing that the finer and more homogeneous nanocrystalline structure of the doped powders results in better-defined and more active catalytic sites, thus improving the performance of the cell.ᅟ [ABSTRACT FROM AUTHOR]