Monodisperse α-Fe₂O₃@SiO₂@Au core/shell nanocomposite spheres: synthesis, characterization and properties

Abstract

A new hybrid spherical structure α-Fe(2)O(3)@SiO(2)@Au with a size of about 141 nm was designed, with a hematite cubic core surrounded by a thick silica shell and further decorated with gold nanoparticles. The monodisperse α-Fe(2)O(3)@SiO(2) spheres were first prepared by a sol-gel process based on the modified Stöber method. Subsequently, the surface of the α-Fe(2)O(3)@SiO(2) particles was functionalized by-NH(2) functional groups. The electrostatic attraction of -NH(2) groups will attach the negatively charged Au nanoparticles to the amino-functionalized α-Fe(2)O(3)@SiO(2) nanospheres in order to prepare α-Fe(2)O(3)@SiO(2) monodisperse hybrid spheres. The M(H) hysteresis loop for α-Fe(2)O(3)@SiO(2) and α-Fe(2)O(3)@SiO(2)@Au spheres indicates that the nanocomposite spheres exhibit superparamagnetic characteristics at room temperature. The optical properties and the application of these hybrid nanocomposites as catalysts for the conversion of CO to CO(2) have also been studied.

Oxidische Nanomaterialien: Von der Synthese über den Mechanismus zur technologischen Innovation

“…Dieser Bildungsmechanismus erfordert eine sorgfältige Einstellung des pH-Werts im Bereich zwischen 3 und 4, um sicherzustellen, dass beide Teilchensorten entgegengesetzt geladen sind (Abbildung 17). Obwohl die erhaltenen kristallinen Anatas-Nanopartikel bereits eine gute Haftung an den siliciumoxidüberzogenen [319] Oxidische Nanomaterialien Angewandte Chemie struiert. [320,321] …”

Design and Synthesis of an Au@MIL‐53(NH2) Catalyst for a One‐Pot Aerobic Oxidation/Knoevenagel Condensation Reaction

“…[13] Therefore, the immobilization of Au NPs on porous supports is regarded as one of the most practical ways to address this problem. Inorganic materials such as SiO 2 , [14,15] TiO 2 , [16,17] and porous carbon [18,19] and organic materials such as poly(4-vinylpyridine), [5] poly(ethylene glycol) dimethacrylate [20] and polyaniline [21] have been utilized as supports to deposit Au NPs. Recently, metal-organic frameworks (MOFs) have been studied as important functional materials due to their tunable crystalline structures and features such as porosity, high surface area and structural flexibility.…”

One-step deposition of Au nanoparticles onto chemically modified ceramic hollow spheres via self-assembly

“…Apart from Au-'Si' composites, the preparation of multifunctional Au-'Si'-Fe composite spheres has also received more attention [30][31][32][33][34][35][36][37]. Au-'Si'-Fe composite spheres are useful as magnetic drug delivery vectors or catalyst supports [32].…”

“…Au-'Si'-Fe composite spheres are useful as magnetic drug delivery vectors or catalyst supports [32]. These type of structures can be built layer-by-layer (LBL) [33][34][35][36], or by covering the 'Si' surface with a single layer made up of Au and iron oxide [30,31]. The LBL approach involves coating the iron oxide-based magnetic NPs with a layer of either 'Si', followed by an over coat of Au NPs [34][35][36], or Au-'Si' core-shell NPs [33].…”

“…These type of structures can be built layer-by-layer (LBL) [33][34][35][36], or by covering the 'Si' surface with a single layer made up of Au and iron oxide [30,31]. The LBL approach involves coating the iron oxide-based magnetic NPs with a layer of either 'Si', followed by an over coat of Au NPs [34][35][36], or Au-'Si' core-shell NPs [33]. The Au layer may adsorb by seeded growth [31,34,35], or direct deposition of Au NPs [30].…”