Template-assisted fabrication of magnetically responsive hollow titania capsules

Magnetically recyclable reduced graphene oxide nanosheets/magnetite-palladium aerogel with superior catalytic activity and reusability

A two-step method was employed to synthesize reduced graphene oxide nanosheets/magnetite-palladium (rGSs/Fe₃O₄-Pd) aerogel, with excellent catalytic activity and recyclability. Firstly, graphene oxide nanosheet (GS) hydrogels were formed by the self-assembly of GSs during the hydrothermal process. Meanwhile, hematite (α-Fe₂O₃) and Pd nanoparticles (NPs) were synthesized and anchored onto the surface of the hydrogel. During heat-treatment, GSs were reduced to rGSs, while nonmagnetic α-Fe₂O₃NPs were converted to magnetic Fe₃O₄ NPs. The as-obtained rGSs/Fe₃O₄-Pd aerogel displayed a three-dimensional interconnected hierarchical porous architecture, which was rich in mesopores and macropores. Such a structure was suitable for catalysis, since it not only improved the mass diffusion and transport, but also readily exposed the catalytic Pd NPs to the reactants. The typical reduction of 4-nitrophenol was chosen as a model reaction to evaluate the catalytic performance of the aerogel. As anticipated, both the reaction rate constant and turn over frequency of the aerogel were much higher than those of the commercial Pd/C catalyst. Moreover, due to incorporation of Fe₃O₄ NPs, the rGSs/Fe₃O₄-Pd aerogel could be magnetically separated from the reaction solution and reused, without obvious loss of catalytic activity.

Correction: Hood, M.A., et al. Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles. Materials 2014, 7, 4057-4087

In [1], several sentences were repeated three times on pages 4062, 4063 and 4065. In addition, many references were incorrect. The errors were introduced by the editorial office during the editing process. We apologize for this mistake and any inconvenience this may have caused to authors and readers. The corrected manuscript is given below.[...].

Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles

This article reviews the recent advances and challenges in the preparation of polymer/inorganic hybrid nanoparticles. We mainly focus on synthetic strategies, basing our classification on whether the inorganic and the polymer components have been formed in situ or ex situ, of the hybrid material. Accordingly, four types of strategies are identified and described, referring to recent examples: (i) ex situ formation of the components and subsequent attachment or integration, either by covalent or noncovalent bonding; (ii) in situ polymerization in the presence of ex situ formed inorganic nanoparticles; (iii) in situ precipitation of the inorganic components on or in polymer structures; and (iv) strategies in which both polymer and inorganic component are simultaneously formed in situ.

Synthesis of magnetic rattle-type nanostructures for use in water treatment

A hydrothermal technique to simultaneously remove a SiO2 template and crystallize a TiO2 outer layer was used to create magnetically separable, hollow rattle-type nanoparticles consisting of a magnetic Fe3O4 core contained within a hollow TiO2 shell. Fe3O4 cores approximately 240 nm in diameter were synthesized, subsequently coated by SiO2 and finally coated with TiO2. This was followed by a hydrothermal treatment to selectively etch the silica, resulting in rattle-type particles with a final outer shell diameter of approximately 390 nm. The product of hydrothermal treatment were rattle-type particles with increased crystallinity and a 68% increase in surface area. Characterization confirmed the ability to etch a hard SiO2 template through use of a simple and benign thermal treatment with pure water, while simultaneously introducing a crystalline phase into the TiO2 active layer. The potential of the particles to be employed as a catalyst in UV induced advanced water treatment for removal of organic contaminants was evaluated through a colorimetric photocatalytic degradation assay using methylene blue as a model contaminant. The ability of the particles to be magnetically separated from solution after treatment and recycled for consecutive treatment cycles was then demonstrated. This technique for selectively removing a hard SiO2 template while simultaneously crystallizing a TiO2 shell avoids the use of hazardous chemical etchants or complex processing, rendering the synthesis of hierarchical, multimaterial, hollow, porous rattle-type particles a simple, attractive, and environmentally friendly "one-pot" technique for potential industrial application.

Controlled synthesis of heterogeneous metal-titania nanostructures and their applications

We describe a new synthetic approach to heterogeneous metal-TiO(2) nanomaterials based on conversion of Ti(3+) to hydrous TiO(2) occurring uniquely on the nanostructured metallic surfaces such as Pt, Au, and Ni nanowires and nanoparticles. The TiO(2) growth mechanism was studied by designing an electrochemical cell. A variety of heterogeneous metal-TiO(2) nanostructures, such as segmented metal-TiO(2) nanowires, core-shell metal-TiO(2) nano/microparticles, and composite metal-TiO(2) nanotubes, can be fabricated by varying the morphology of the seeding metal nanostructure or controlling selective TiO(2) growth on different surfaces of the metallic nanomaterial. Altering the reaction time and Ti(3+) concentration allows the TiO(2) segment lengths or TiO(2) shell thicknesses to be finely tuned. Coaxial Au-TiO(2) nanorod arrays were demonstrated to be fast lithium-ion storage materials, while the core-shell Ni-TiO(2) nanoparticles exhibited excellent photodegradation properties as magnetic recyclable photocatalysts.

Alkaline hydrothermal synthesis of homogeneous titania microspheres with urchin-like nanoarchitectures for dye effluent treatments

The heterogeneous photocatalysis technique to treat dye effluents demands micrometer-sized titania aggregates with one-dimensional nanostructures, which possess high photocatalytic activity and at the same time facilitate the catalyst-recovery from a slurry system. In this study, the solution remained after interactions between metallic Ti and hydrogen peroxide was subjected to an alkaline hydrothermal treatment. Microspheres with extremely uniform sizes of ca. 2 μm in diameter were achieved after a subsequent proton exchange followed by calcination in air. The microspheres were urchin-like aggregates of radially assembled nanowires, which consisted of chain-like anatase single crystallites with an average diameter of 20-25 nm. The homogeneous microspheres calcinated at 600°C possessed a surface area of 45.4m(2)/g and exhibited an excellent activity to assist photodegradation of rhodamine B in water, which is significantly higher than that of P25 titania nanoparticles. Because of the much easier recovery of the photocatalyst, the homogeneous microspheres synthesized herein may find practical applications in efficient photocatalytic treatments of dye effluents.