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A facile method of coating polystyrene (PS) particles with organo-silica and their functionalization was presented. By adding the organo-silane precursor into PS aqueous solution in presence of ammonia, an organo-silica shell could be coated on PS particles directly. This method has several characteristics. First, only one process, one precursor and one solvent were used. Second, the organic groups could be varied from methyl, propyl, vinyl, to mercaptopropyl. The third is the tunable shell thickness with a high monodispersity. The organo-silica shells are further functionalized. The PS@vinyl-SiO 2 particles were used to assemble colloidal crystals, and further modified with bromine, resulting in tunable photonic band gaps. PS@mercaptopropyl-SiO 2 particles allow the encapsulation of Au nanoparticles. The resulting 2.2 nm Au particles were stable at 550 °C and well-distributed in the whole SiO 2 shell with a loading up to 20 wt%. [ABSTRACT FROM AUTHOR]

UV dye DMT-doped silica films were prepared by sol–gel process with dioxane as the cosolvent. Luminescence quenching was not observed even if the DMT concentration in the visibly transparent silica film is as high as 1.26×10−2 M. The emission peaks centered at ∼375 nm for the films show red-shift of 35–45 nm, comparing with that of the cyclohexane solution of DMT. The fluorescence quantum efficiency of the films centered at ∼590 nm are larger than those at ∼375 nm. [Copyright &y& Elsevier]

About 15 years ago, the Ryoo group described the synthesis of CMK-5, a material consisting of a hexagonal arrangement of carbon nanotubes. Extension of the surface casting synthesis to oxide compositions, however, was not possible so far, in spite of many attempts. Here it is demonstrated, that crystalline mesoporous hollow zirconia materials with very high surface areas up to 400 m2 g−1, and in selected cases in the form of CMK-5-like, are indeed accessible via such a surface casting process. The key for the successful synthesis is an increased interaction between the silica hard template surface and the zirconia precursor species by using silanol group-rich mesoporous silica as a hard template. The surface areas of the obtained zirconias exceed those of conventionally hard-templated ones by a factor of two to three. The surface casting process seems to be applicable also to other oxide materials. [ABSTRACT FROM AUTHOR]

About 15 years ago, the Ryoo group described the synthesis of CMK-5, a material consisting of a hexagonal arrangement of carbon nanotubes. Extension of the surface casting synthesis to oxide compositions, however, was not possible so far, in spite of many attempts. Here it is demonstrated, that crystalline mesoporous hollow zirconia materials with very high surface areas up to 400 m2 g−1, and in selected cases in the form of CMK-5-like, are indeed accessible via such a surface casting process. The key for the successful synthesis is an increased interaction between the silica hard template surface and the zirconia precursor species by using silanol group-rich mesoporous silica as a hard template. The surface areas of the obtained zirconias exceed those of conventionally hard-templated ones by a factor of two to three. The surface casting process seems to be applicable also to other oxide materials. [ABSTRACT FROM AUTHOR]

A simple and scalable method for synthesizing Co3O4 nanoparticles supported on the framework of mesoporous carbon (MC) was developed. Benefiting from an ion-exchange process during the preparation, the cobalt precursor is introduced into a mesostructured polymer framework that results in Co3O4 nanoparticles (ca. 3 nm) supported on MC (Co3O4/MC) with narrow particle size distribution and homogeneous dispersion after simple reduction/pyrolysis and mild oxidation steps. The as-obtained Co3O4/MC is a highly efficient catalyst for transfer hydrogenation of α,β-unsaturated aldehydes. Selectivities towards unsaturated alcohols are always higher than 95 % at full conversion. In addition, the Co3O4/MC shows high stability under the reaction conditions, it can be recycled at least six times without loss of activity. [ABSTRACT FROM AUTHOR]

A simple and scalable method for synthesizing Co3O4 nanoparticles supported on the framework of mesoporous carbon (MC) was developed. Benefiting from an ion-exchange process during the preparation, the cobalt precursor is introduced into a mesostructured polymer framework that results in Co3O4 nanoparticles (ca. 3 nm) supported on MC (Co3O4/MC) with narrow particle size distribution and homogeneous dispersion after simple reduction/pyrolysis and mild oxidation steps. The as-obtained Co3O4/MC is a highly efficient catalyst for transfer hydrogenation of α,β-unsaturated aldehydes. Selectivities towards unsaturated alcohols are always higher than 95 % at full conversion. In addition, the Co3O4/MC shows high stability under the reaction conditions, it can be recycled at least six times without loss of activity. [ABSTRACT FROM AUTHOR]

Nanoscopic gold particles have gained very high interest because of their promising catalytic activity for various chemicals reactions. Among these reactions, low-temperature CO oxidation is the most extensively studied one due to its practical relevance in environmental applications and the fundamental problems associated with its very high activity at low temperatures. Gold nanoparticles supported on manganese oxide belong to the most active gold catalysts for CO oxidation. Among a variety of manganese oxides, Mn2O3 is considered to be the most favorable support for gold nanoparticles with respect to catalytic activity. Gold on MnO2 has been shown to be significantly less active than gold on Mn2O3 in previous work. In contrast to these previous studies, in a comprehensive study of gold nanoparticles on different manganese oxides, we developed a gold catalyst on MnO2 nanostructures with extremely high activity. Nanosized gold particles (2-3 nm) were supported on α-MnO2 nanowires and mesoporous β-MnO2 nanowire arrays. The materials were extremely active at very low temperature (-80 °C) and also highly stable at 25 °C (70 h) under normal conditions for CO oxidation. The specific reaction rate of 2.8 molCO•h-1•gAu-1 at a temperature as low as -85 °C is almost 30 times higher than that of the most active Au/Mn2O3 catalyst. [ABSTRACT FROM AUTHOR]

Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio-oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen-doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal ( p6 m) or 3D cubic ( Im [ABSTRACT FROM AUTHOR]

Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio-oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen-doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal ( p6 m) or 3D cubic ( Im [ABSTRACT FROM AUTHOR]

Co3O4 with a spinel structure is a very active oxide catalyst for the oxidation of CO. In such catalysts, octahedrally coordinated Co3+ is considered to be the active site, while tetrahedrally coordinated Co2+ is assumed to be basically inactive. In this study, a highly ordered mesoporous CoO has been prepared by H2 reduction of nanocast Co3O4 at low temperature (250 °C). The as-prepared CoO material, which has a rock-salt structure with a single Co2+ octahedrally coordinated by lattice oxygen in Fm3m symmetry, exhibited unexpectedly high activity for CO oxidation. Careful investigation of the catalytic behavior of mesoporous CoO catalyst led to the conclusion that the oxidation of surface Co to Co3+ causes the high activity. Other mesoporous spinels (CuCo2O4, CoCr2O4, and CoFe2O4) with different Co species substituted with non/low-active metal ions were also synthesized to investigate the catalytically active site of cobalt-based catalysts. The results show that not only is the octahedrally coordinated Co3+ highly active but also the octahedrally coordinated Co2+ species in CoFe2O4 with an inverse spinel structure shows some activity. These results suggest that the octahedrally coordinated Co2+ species is easily oxidized and shows high catalytic activity for CO oxidation. [ABSTRACT FROM AUTHOR]

We describe a solid polyphenylene support that serves as an excellent platform for metal-catalyzed reactions that are normally carried out under homogeneous conditions. The catalyst is synthesized by palladium-catalyzed Suzuki coupling which directly results in formation of palladium nanoparticles confined to a porous polyphenylene network. The composite solid is in turn highly active for further Suzuki coupling reactions, including non-activated substrates that are challenging even for molecular catalysts. [ABSTRACT FROM AUTHOR]

We describe a solid polyphenylene support that serves as an excellent platform for metal-catalyzed reactions that are normally carried out under homogeneous conditions. The catalyst is synthesized by palladium-catalyzed Suzuki coupling which directly results in formation of palladium nanoparticles confined to a porous polyphenylene network. The composite solid is in turn highly active for further Suzuki coupling reactions, including non-activated substrates that are challenging even for molecular catalysts. [ABSTRACT FROM AUTHOR]

The synthesis of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) is a highly attractive route to a renewable fuel. However, achieving high yields in this reaction is a substantial challenge. Here it is described how PtCo bimetallic nanoparticles with diameters of 3.6 ± 0.7 nm can solve this problem. Over PtCo catalysts the conversion of HMF was 100% within 10 min and the yield to DMF reached 98% after 2 h, which substantially exceeds the best results reported in the literature. Moreover, the synthetic method can be generalized to other bimetallic nanoparticles encapsulated in hollow carbon spheres. [ABSTRACT FROM AUTHOR]

In cracking from: Highly engineered bifunctional yolk–shell nanocatalysts with tailored structural configuration, that is, hollow carbon spheres as the matrix, entrapped magnetite nanoparticles in the core, and in situ formed and highly dispersed noble metal nanoparticles within the carbon shells as active catalytic sites, were prepared. These nanocatalysts show high activity, reusability, and good magnetic separation properties. [ABSTRACT FROM AUTHOR]

Porous carbon monoliths with defined multilength scale pore structures, a nitrogen-containing framework, and high mechanical strength were synthesized through a self-assembly of poly(benzoxazine-co-resol) and a carbonization process. Importantly, this synthesis can be easily scaled up to prepare carbon monoliths with identical pore structures. By controlling the reaction conditions, porous carbon monoliths exhibit fully interconnected macroporosity and mesoporosity with cubic Im3m symmetry and can withstand a press pressure of up to 15.6 MPa. The use of amines in the synthesis results in a nitrogen-containing framework of the carbon monolith, as evidenced by the cross-polarization magic-angle-spinning NMR characterization. With such designed structures, the carbon monoliths show outstanding CO2 capture and separation capacities, high selectivity, and facile regeneration at room temperature. At ~1 bar, the equilibrium capacities of the monoliths are in the range of 3.3-4.9 mmol g-1 at 0 °C and of 2.6-3.3 mmol g-1 at 25 °C, while the dynamic capacities are in the range of 2.7-4.1 wt % at 25 °C using 14% (v/v) CO2 in N2. The carbon monoliths exhibit high selectivity for the capture of CO2 over N2 from a CO2/N2 mixture, with a separation factor ranging from 13 to 28. Meanwhile, they undergo a facile CO2 release in an argon stream at 25 °C, indicating a good regeneration capacity. [ABSTRACT FROM AUTHOR]

Mesoporous CoO is prepared by H2 reduction of nanocast Co3O4 at 250 °C for 1.5 h. [ABSTRACT FROM AUTHOR]