STEM study on the morphological evolution of copper-based nanoparticles during high-temperature redox reactions.

Despite the broad relevance of copper nanoparticles in industrial applications, the fundamental understanding of oxidation and reduction of copper at the nanoscale is still a matter of debate and remains within the realm of bulk or thin film-based systems. Moreover, the reported studies on nanoparticles vary widely in terms of experimental parameters and are predominantly carried out using either ex situ observation or environmental transmission electron microscopy in a gaseous atmosphere at low pressure. Hence, dedicated studies in regards to the morphological transformations and structural transitions of copper-based nanoparticles at a wider range of temperatures and under industrially relevant pressure would provide valuable insights to improve the application-specific material design.

In situ QXAS study of sulfidation/oxidative regeneration reactions of zinc molybdate (ZnMoO) and ZnO-MoO materials.

Recent technologies such as those using coal, natural gas or biomass as fuel are often facing the challenge of removing H2S impurities. Among the various existing routes for sulfur removal, the conversion of transition metal oxides into sulfides is often considered for deep gas purification. The ideal regenerative system, preventing waste generation, should combine a high affinity material towards H2S and an easy way for its regeneration into the initial oxide form.

Use of polyols as particle size and shape controllers: application to boehmite synthesis from sol-gel routes.

Polyols were successfully used as size and shape controllers of oxide nanoparticles synthesized by soft chemistry in aqueous solution. The efficiency of acyclic polyols as a complexing agent depends obviously on the number of OH groups bonded to the carbon chain (and thus on the carbon chain length), but also on their stereochemistry. This innovating way to control morphology has been experienced for the synthesis of boehmite nanoparticles, whose morphology variations related to xylitol adsorption (C5 alditol) have been previously reported.

Growth of boehmite particles in the presence of xylitol: morphology oriented by the nest effect of hydrogen bonding.

The ability to design nanoparticles size and shape through the addition of simple and commercially available organic molecules is of particular interest in the catalytic domain because huge amounts of very fine powders are needed. The origin of this effect is all the more difficult to elucidate because the involved interactions are weak. In this paper, we have investigated the shaping of boehmite AlO(OH) nanoparticles in the presence of polyols like xylitol (C(5) alditol) by a combined experimental and theoretical approach.

Design of liquid-crystalline aqueous suspensions of rutile nanorods: evidence of anisotropic photocatalytic properties.

TiO2 rutile nanorods of average length L = 160 +/- 40 nm and average diameter D = 15 +/- 5 nm have been synthesized through a seed-mediated growth process by TiCl4 hydrolysis in concentrated acidic solution. These nanorods were dispersed in water to yield stable (aggregation-free) colloidal aqueous suspensions. At volume fractions phi > 3%, the suspensions spontaneously display a phase separation into an isotropic liquid phase and a liquid-crystalline phase identified as nematic by X-ray scattering.