Synthesis of small Ni-core-Au-shell catalytic nanoparticles on TiO2 by galvanic replacement reaction

We report the first preparation of small gold–nickel (AuNi) bimetallic nanoparticles (<5 nm) supported on titania by the method of galvanic replacement reaction (GRR), evidenced by the replacement of Ni atoms by Au atoms according to the stoichiometry of the reaction. We showed that this preparation method allowed not only the control of the gold and nickel contents in the samples, but also the formation of small bimetallic nanoparticles with strained core–shell structures, as revealed by aberration-corrected scanning transmission electron microscopy in combination with energy-dispersive X-ray spectroscopy mapping. The catalytic characterization by the probe reaction of semi-hydrogenation of butadiene showed that the resulting nickel-based nanocatalysts containing a small amount of gold exhibited higher selectivity to butenes than pure nickel catalysts and a high level of activity, closer to that of pure nickel catalysts than to that of pure gold catalysts. These improved catalytic performances could not be explained by a mere structural model of simple core–shell structure of the nanoparticles. Instead, they could come from the incorporation of Ni within the gold surface and/or from surface lattice relaxation and subsurface misfit defects

Ecodesign of ordered mesoporous silica materials

International audienceCharacterized by a regular porosity in terms of pore size and pore network arrangement, ordered mesoporous solids have attracted increasing interest in the last two decades. These materials have been identified as potential candidates for several applications. However, more nvironmentally friendly and economical synthesis routes of mesoporous silica materials were found to be necessary in order to develop these applications on an industrial scale. Consequently, ecodesign of ordered mesoporous silica has been considerably developed with the objective of optimizing the chemistry and the processing aspects of the material synthesis. In this review, the main strategies developed with this aim are presented and discussed

Mesoscopic superstructures of flexible porous coordination polymers synthesized via coordination replication

The coordination replication technique is employed for the direct conversion of a macro- and mesoporous Cu(OH)2-polyacrylamide composite to three-dimensional superstructures consisting of the flexible porous coordination polymers, Cu2(bdc)2(MeOH)2 and Cu2(bdc)2(bpy) (bdc2- = 1, 4-benzenedicarboxylate, bpy = 4, 4′-bipyridine). Detailed characterization of the replicated systems reveals that the structuralization plays an important role in determining the adsorptive properties of the replicated systems, and that the immobilization of the crystals within a higher-order architecture also affects its structural and dynamic properties. The polyacrylamide polymer is also found to be crucial for maintaining the structuralization of the monolithic systems, and in providing the mechanical robustness required for manual handling. In all, the results discussed here demonstrate a significant expansion in the scope of the coordination replication strategy, and further confirms its utility as a highly versatile platform for the preparation of functional three-dimensional superstructures of porous coordination polymers

Novel 8-Oxotheaspiranes and Dihydro Analogues Possessing a Partly Fluorinated Ring

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Mechanically stable, hierarchically porous Cu3(btc)2 (HKUST-1) monoliths via direct conversion of copper(ii) hydroxide-based monoliths.

The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc(3-) = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors

Thermosensitive and drug-loaded ordered mesoporous silica: a direct and effective synthesis using PEO-b-PNIPAM block copolymers

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Synthesis of poly(ethylene oxide)-b-poly(N-isopropylacrylamide) by RAFT polymerization and their utilization as structure directing agents for the preparation of functionalized mesoporous silica

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Synthesis of double hydrophilic block copolymers by ATRP and their assembly induced by complexation

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Porous Nickel‐Alumina Derived from Metal‐Organic Framework (MIL‐53): A New Approach to Achieve Active and Stable Catalysts in Methane Dry Reforming

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