Although Au catalysts can be readily prepared on titania via the deposition-precipitation (DP) method, the direct application of the method similar to the preparation of silica-supported Au catalysts only results in diminished success. This paper reports a novel, efficient method to synthesize highly active Au catalysts supported on mesoporous silica (SBA-15) through a gold cationic complex precursor [Au(en)2]3+ (en = ethylenediamine) via a wet chemical process. The gold cationic precursor was immobilized on negatively charged surfaces of silica by a unique DP method that makes use of the deprotonation reaction of ethylenediamine ligands. The resulting mesoporous catalyst has been demonstrated to be highly active for CO oxidation at room temperature and even below 273 K, the activity of which is much superior to that of silica-supported Au catalysts previously prepared by various solution techniques. The pH value of the gold precursor solution plays a key role in determining the catalytic activity through the regulation of [Au(en)2]3+ deprotonation reaction and the surface interaction of silica with the gold precursor. This mesoporous gold silica catalyst has also been shown to be highly resistant to sintering because of the stabilization of Au nanoparticles inside mesopores.

An ionothermal process was employed to synthesize the hierarchical structures of zinc oxide with diverse morphologies. The key to this synthesis methodology was the use of metal-containing ionic liquids that acted both as solvents and as metal precursors in the ionothermal process. The growth environment was highly homogeneous, allowing facile control over reaction conditions. The morphologies of zinc oxide were strongly dependent on the nature of the corresponding ionic-liquid precursors, providing unique methodologies to control growth conditions.

No abstract

Highly ordered large mesopore organosilicas have been obtained by direct liquid crystal templating in acid media using bridged silsesquioxane (EtO)3Si−CH2−CH2−Si(OEt)3 [bis(triethoxysilyl)ethane, BTSE] precursor and triblock copolymers as structure-directing species. The degree of long-range ordering of the structure as determined from X-ray diffraction and transmission electron microscopy, and the most probable pore diameter, in the range 4−8 nm, were observed to depend on the concentration of triblock copolymer used in the synthesis. Further pore-wall functionalization was achieved by co-condensation with Cu(II)-complexed N,N‘-bis[3-(trimethoxysilyl)propyl]ethylenediamine (BTSPED). Surfactant extraction produces periodic mesoporous organosilicas functionalized with this complex in the framework, from which the Cu(II) can then be removed by acid leaching. Such hybrid bridged bifunctional organosilicas are homogeneously mesoporous, and the pore diameter increases in the range 11−21 nm as the mole ratio of BTSPED to BTSE is increased from 0.1 to 0.3. 29Si MAS NMR shows that under the conditions used, no cleavage of the Si−C bond occurs, and suggests that the degree of condensation is higher in the bridged bifunctional organosilicas than in the bridged monofunctional organosilicas.