Hydrophobic Nanoreactor Soft‐Templating: A Supramolecular Approach to Yolk@Shell Materials

Abstract

wileyonlinelibrary.comin the fi elds of heterogeneous catalysis, [1][2][3][4] electrocatalysis, [ 2,5,6 ] gas sensing, [ 7,8 ] battery development, [ 9,10 ] and drug delivery. [ 5,11 ] Yolk@shell materials are composed of single (or multiple) nanoscaled cores of a material A encapsulated inside a hollow nanosphere of a material B (A@void@B, in short A@B). Depending on the envisioned application, the surrounding hollow shell can be dense or porous (permeable) allowing control of the interactions between the core and the outer environment.For many applications, it has been shown that yolk@shell nanocomposites feature enhanced properties as a result of their unique structure on the nanometer scale. In the fi eld of heterogeneous catalysis for example, it has been demonstrated that supported metal nanoparticle (M NP ) catalysts with a yolk@shell structure are highly resistant against temperature and/or reaction induced M NP sintering, thus preserving the catalysts activity. As such, a variety of yolk@shell nanocatalysts have been designed, including M NP @carbon, [12][13][14] M NP @silica, [ 2,15 ] Au NP @TiO 2 , [ 16 ] and Au NP @ZrO 2 , [ 17,18 ] all superior in terms of catalytic activity and stability when compared to their non-yolk@shell counterparts.Despite their proven potential, the application of yolk@shell structures remains however limited due to challenging and Due to their unique morphology-related properties, yolk@shell materials are promising materials for catalysis, drug delivery, energy conversion, and storage. Despite their proven potential, large-scale applications are however limited due to demanding synthesis protocols. Overcoming these limitations, a simple softtemplated approach for the one-pot synthesis of yolk@shell nanocomposites and in particular of multicore metal nanoparticle@metal oxide nanostructures (M NP @MO x ) is introduced. The approach here, as demonstrated for Au NP @ ITO TR (ITO TR standing for tin-rich ITO), relies on polystyrene-block -poly(4vinylpyridine) (PS-b -P4VP) inverse micelles as two compartment nanoreactor templates. While the hydrophilic P4VP core incorporates the hydrophilic metal precursor, the hydrophobic PS corona takes up the hydrophobic metal oxide precursor. As a result, interfacial reactions between the precursors can take place, leading to the formation of yolk@shell structures in solution. Once calcined these micelles yield Au NP @ITO TR nanostructures, composed of multiple 6 nm sized Au NPs strongly anchored onto the inner surface of porous 35 nm sized ITO TR hollow spheres. Although of multicore nature, only limited sintering of the metal nanoparticles is observed at high temperatures (700 °C). In addition, the as-synthesized yolk@shell structures exhibit high and stable activity toward CO electrooxidation, thus demonstrating the applicability of our approach for the design of functional yolk@shell nanocatalysts.

Functionalization of Hollow Nanomaterials for Catalytic Applications: Nanoreactor Construction

“…A typical catalytic process comprises of diffusion, adsorption/desorption, and surface reaction, which should be fully taken into account for the reactor design. By precisely tuning the microstructural parameters via the controllable synthetic methods, the entire catalytic process becomes manageable on the rational designed hollow nanomaterials . As shown in Figure , there are several tunable structural sections in spatial extent for the further functionalization, such as, exterior surface, interior surface, pore structure in the shell, void, etc.…”

Magneto‐Mechanical Surfaces Design

“…Nanocomposites are dispersions of magnetic nanoparticles (MNP) in a typically polymeric matrix. The range of available MNPs is in permanent growth, from new rare earth magnetic compositions, to novel superparamagnetic particles with functional coatings, or even particle clusters of controlled size and multifunctionality, Table summarizes some of the most common magnetic nanoparticles employed for this purpose.…”

Trendbericht Technische Chemie

“…25) Interessant als Materialklasse sind Kombinationen klassischer Trägermaterialien in der Schale, etwa SiO 2 , und Aktivmaterial im Kern. [26][27][28] 29) Neue Trends zeigen sich vor allem in der Übertragung der regelmäßigen Porenstruktur geordneter mesoporöser Materialien auf andere Materialklassen wie Metalle, Karbide, Nitride und Kohlenstoffe. [30][31][32][33] Problematisch beim Optimieren von Stofftransport und Reaktion sind neben der Materialsynthese vor allem komplexe Reaktionen, etwa die Fischer-Tropsch-Synthese.…”