SBA-15 mesoporous silica has been functionalized with aminopropyl groups through a simple co-condensation approach of tetraethyl orthosilicate (TEOS) and (3-aminopropyl)triethoxysilane (APTES) using amphiphilic block copolymers under acidic conditions. The organic-modified SBA-15 materials have hexagonal crystallographic order, pore diameter up to 60 A, and the content of aminopropyl groups up to 2.3 mmol g(-1). The influences of TEOS prehydrolysis period and APTES concentration on the crystallographic order, pore size, surface area, and pore volume were examined. TEOS prehydrolysis prior to the addition of APTES was found essential to obtain well-ordered mesoporous materials with amino functionality. The amount of APTES incorporated in the silica framework increased with the APTES concentration in the synthesis gel, while the ordering of the mesoporous structure gradually decreased. Analysis with TG, IR, and solid state NMR spectra demonstrated that the aminopropyl groups incorporated in SBA-15 were not decomposed during the preparation procedure and the surfactant P123 was fully removed through ethanol extraction. The modified SBA-15 was an excellent base catalyst in Knoevenagel and Michael addition reactions.

The surface of CuO is known for its hydrophilicity and exhibits superhydrophilic nature as nanowires are present. When exposed in the air at room temperature or treated by low temperature annealing, however, transition from superhydrophilicity to superhydrophobicity of the CuO nanowire films are observed. Since the chemical structure of the films after treatment remains the same as CuO according to x-ray photoelectron spectroscopy spectra, the superhydrophobicity may be attributed to partial deoxidation of the upmost layer of CuO surfaces into Cu2O-like hydrophobic surfaces. Nonetheless, superhydrophilicity is recovered if the superhydrophobic CuO film is subject to high temperature annealing.

A facile synthesis route for preparing SBA-15 silica of platelet shape and very short mesochannels (150-350 nm) was developed by introducing a small amount of Zr(IV) ions in the synthesis solution.The synthesis route can be easily extended to prepare platelet SBA-15 materials with various organic functional groups up to 1.87 mmol/g loading in one pot. In situ XRD and freeze-fracture replication TEM were found to be powerful techniques for studying the self-assembly processes. The platelet SBA-15 with short mesochannels in 150-350 nm was formed because of the fast self-assembly rate of P123 micelles and TEOS accelerated by the Zr(IV) ions in the synthesis solution. The platelet SBA-15 materials are superior to the conventional SBA-15 of rod or fiber morphologies in facilitating molecular diffusion and less possibility of pore blockage when used in the sorption or reactions of bulky molecules.

An environmentally friendly process of synthesizing Zr-incorporated mesoporous SBA-15 silica materials with the Zr content up to 0.1 Zr/Si atomic ratio and of well-ordered pore structure, high surface area, and narrow pore-size distribution was developed, where no addition of mineral acids was necessary. The main strategy of this method was to utilize the acidity self-generated in the aqueous solutions of the zirconium precursors as the catalyst for TEOS hydrolysis. In addition, the zirconium precursors also contributed to salt effect in increasing the ordering of the mesostructure. SBA-15 materials of highly ordered pores were obtained without the addition of mineral acids when the Zr/Si ratios were around 0.05. For those with the Zr/Si ratios smaller or greater than this value, the introduction of some salts, such as NaCl, in the synthesis gel was found essential in order to obtain mesostructure of high ordering and narrow pore size distribution. The amount of Zr incorporated in SBA-15 synthesized under such a mild condition was greater than that synthesized in a strong acidic environment. Moreover, the Zr content, up to Zr/Si ratio of 0.1, was close to that started with in the gel. The morphology of the Zr-SBA-15 material was found to vary with the acidity of the synthesis gels. Rodlike shape morphology was observed when no mineral acids were used, in contrast to the hexagonal platelet morphology for the material synthesized in a strong acidic environment.

The formation of CoSi and CoSi 2 in Si nanowires at 700 and 800°C, respectively, by point contact reactions between nanodots of Co and nanowires of Si have been investigated in situ in a ultrahigh vacuum high-resolution transmission electron microscope. The CoSi 2 has undergone an axial epitaxial growth in the Si nanowire and a stepwise growth mode was found. We observed that the stepwise growth occurs repeatedly in the form of an atomic step sweeping across the CoSi 2 /Si interface. It appears that the growth of a new step or a new silicide layer requires an independent event of nucleation. We are able to resolve the nucleation stage and the growth stage of each layer of the epitaxial growth in video images. In the nucleation stage, the incubation period is measured, which is much longer than the period needed to grow the layer across the silicide/Si interface. So the epitaxial growth consists of a repeating nucleation and a rapid stepwise growth across the epitaxial interface. This is a general behavior of epitaxial growth in nanowires. The axial heterostructure of CoSi 2 /Si/CoSi 2 with sharp epitaxial interfaces has been obtained. A discussion of the kinetics of supply limited and source-limited reaction in nanowire case by point contact reaction is given. The heterostructures are promising as high performance transistors based on intrinsic Si nanowires.

Large-area, vertically aligned silicon nanowire ͑SiNW͒ arrays have been successfully synthesized in an aqueous solution containing AgNO 3 and HF on ͑001͒Si substrates. The as-synthesized SiNWs were determined to be perfectly single crystalline with the axis of the wire parallel to the ͓001͔ direction. The typical widths of the SiNWs were in the range of 30-200 nm. The lengths of SiNWs could be tuned from several to tens of micrometers by adjusting the synthesis temperature and time. We measured the formation rate at different reaction temperatures. The activation energy for linear growth of the SiNWs, as obtained from an Arrhenius plot, was found to be about 0.36 eV. In addition, the Si substrates with highly oriented SiNW arrays were found to exhibit significant hydrophobic properties. The water contact angles of the HF-treated SiNW arrays were measured to be about 120-148°, much greater than that with a flat silicon wafer surface ͑ϳ85 to 88°͒.

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Three supported Pt/Fe 2 O 3 catalysts were prepared by depositing platinum colloids with discrete particle sizes onto the surface of Fe(OH) 3 powders, which were then calcined at an elevated temperature. Pt nanoparticle colloids with mean diameters of 1.1, 1.9 or 2.7 nm were synthesized in order to investigate the effects of particle size on the structure and CO oxidation properties of these Pt/Fe 2 O 3 catalysts. All Pt/Fe 2 O 3 catalysts demonstrated activity in low-temperature CO oxidation, with the sample containing Pt nanoparticles with a mean diameter of 1.9 nm (designated Pt-Fe 2 O 3 -b) exhibiting relatively higher catalytic activity. Compared with the other two catalysts, Pt/Fe 2 O 3 -b exhibited an increased ability to activate oxygen and maintain the stability of Pt species, correlating with its higher catalytic activity. The results of various characterization techniques revealed that the mean particle size of the Pt nanoparticles could influence the chemical states of Pt species and the strength of metal-support interactions of the Pt/Fe 2 O 3 catalysts. It was observed that the metal-support interactions in Pt/Fe 2 O 3 catalysts were able to adjust the redox properties and the O 2 -activation abilities of the catalysts. Finally, it is proposed that the interacting Pt and Fe species located at the Pt-FeO x interface are the primary active sites for the activation of CO and O 2 , respectively.