A novel route of colloidal chemistry: room temperature reactive interactions between titanium monoxide and silicon monoxide sols produced by laser ablation in liquid resulting in the formation of titanium disilicide.

In spite of advanced research on functional colloidal inorganic nanoparticles and their reactivity, room temperature reactive interactions between two different colloids have remained challenging so far. Laser ablation of titanium monoxide and silicon monoxide in ethanol and water allows the generation of TiO-derived and SiO-derived colloidal nanoparticles which were characterized for their stability, size distribution and zeta potentials with dynamic light scattering and after evaporation of solvent examined for their morphology, chemical and phase composition by scanning electron microscopy, Raman spectroscopy, high resolution transmission electron microscopy and electron diffraction and small angle X-ray scattering. Aqueous and ethanolic TiO-derived colloids consist of anatase and monoclinic TiO, while ethanolic SiO-derived colloids are composed of crystalline and amorphous Si, nanocrystalline Si and SiO2 and aqueous SiO-derived colloids contain, in addition to these phases, a high pressure form of cristobalite. Simple room temperature mixing of ethanolic TiO- and SiO-derived colloids allows the formation of TiSi2, which is a case of so far unreported room temperature reactive interactions between two colloidal species. All colloids absorb solar light and act as photocatalysts for methylene blue degradation. These findings present a challenge for further search for feasible room-temperature reactions between distinct colloidal particles and open the potential for green synthesis of other desirable and hardly achievable phases.

Synthesis, Characterization, and Gas Adsorption Performance of Amine-Functionalized Styrene-Based Porous Polymers.

In recent years, porous materials have been extensively studied by the scientific community owing to their excellent properties and potential use in many different areas, such as gas separation and adsorption. Hyper-crosslinked porous polymers (HCLPs) have gained attention because of their high surface area and porosity, low density, high chemical and thermal stability, and excellent adsorption capabilities in comparison to other porous materials. Herein, we report the synthesis, characterization, and gas (particularly CO2) adsorption performance of a series of novel styrene-based HCLPs. The materials were prepared in two steps. The first step involved radical copolymerization of divinylbenzene (DVB) and 4-vinylbenzyl chloride (VBC), a non-porous gel-type polymer, which was then modified by hyper-crosslinking, generating micropores with a high surface area of more than 700 m2 g-1. In the following step, the polymer was impregnated with various polyamines that reacted with residual alkyl chloride groups on the pore walls. This impregnation substantially improved the CO2/N2 and CO2/CH4 adsorption selectivity.

Chemical vapor deposition of germanium-rich CrGe x nanowires.

Chemical vapor deposition was applied to synthetize nanostructured deposits containing several sorts of nanoobjects (i.e., nanoballs, irregular particles, and nanowires). Analytical techniques, that is, high-resolution transmission electron microscopy, scanning electron microscopy, electron dispersive X-ray analysis, selected area electron diffraction, and X-ray photoelectron spectroscopy, showed that unlike nanoballs and particles composed of crystalline germanium, the layer was made of chromium germanide CrGe x . The nanowires possessed a complex structure, namely a thin crystalline germanium core and amorphous CrGe x coating. The composition of the nanowire coating was [Cr]/[Ge] = 1:(6-7). The resistance of the nanowire-deposit system was estimated to be 2.7 kΩ·cm using an unique vacuum contacting system.

Novel perspectives of laser ablation in liquids: the formation of a high-pressure orthorhombic FeS phase and absorption of FeS-derived colloids on a porous surface for solar-light photocatalytic wastewater cleaning.

A pulsed Nd : YAG laser ablation of FeS in water and ethanol produces FeS-derived colloidal nanoparticles that absorb onto immersed porous ceramic substrates and create solar-light photocatalytic surfaces. The stability, size distribution and zeta potential of the nanoparticles were assessed by dynamic light scattering. Raman, UV-Vis and XP spectroscopy and electron microscopy reveal that the sol nanoparticles have their outmost layer composed of ferrous and ferric sulphates and those produced in water are made of high-pressure orthorhombic FeS, cubic magnetite Fe3O4 and tetragonal maghemite γ-Fe2O3, while those formed in ethanol contain hexagonal FeS and cubic magnetite Fe3O4. Both colloids absorb solar light and their adsorption to porous ceramic surfaces creates functionalized ceramic surfaces that induce methylene blue degradation by daylight. The laser induced process thus offers an easy and efficient way for the functionalization of porous surfaces by photocatalytic nanoparticles that avoids aggregation in the liquid phase. The formation of an orthorhombic high-pressure FeS phase stable under ambient conditions is the first example of high-pressure structures produced by laser ablation in liquid without the assistance of an electric field.