Raspberry-like hollow SiO2 spheres were synthesized successfully through a dual latex−surfactant templating route. In this approach, cationic cetyltrimethylammonium (CTA+) micelles and microscale polystyrene (PS) latex were employed as structure-directing templates for constructing the inorganic hollow SiO2 spheres with hierarchical structures. The final product has been analyzed scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), single-angle X-ray diffraction (SAXRD), Brunauer−Emmett−Teller (BET) measurements, and Hg porosimetry measurements. The as-obtained hollow SiO2 spheres present a novel raspberry-like protruding surface morphology and possess hierarchical porous shells. Moreover, the factors that could impact the surface morphology and hierarchical porous structure are discussed, and the corresponding mechanism was proposed accordingly. This dual templating route is expected to be an effective means to pattern multiscale structures in the shell of the SiO2 microspheres; hence their potential applications could be greatly broadened.

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By using the in situ thermal analysis-mass spectroscopic technique, combined with transmission electron microscopic characterization of the carbon nanotube (CNT) product, we have studied the chemical vapor deposition (CVD) growth of CNTs with Fe-Co/gamma-Al2O3 catalyst and benzene precursor in the range of room temperature to 700 degrees C. The growth process has been clearly illuminated, which starts from the reduction of catalyst around 645 degrees C followed by the dissociation of carbon-hydrogen bonds of benzene and the sequential growth of CNTs. A surprising fact is that no possible hydrocarbon species derived from benzene was detected, indicating that the carbon-carbon bond was not broken under our experimental conditions. All of the experimental results strongly reinforce the six-membered-ring-based growth model, and a schematic elucidation is presented accordingly. This in situ study not only reveals the unique and convincing information directly related to the growth mechanism from the involved chemistry, but also provides a powerful way to clarify the mechanism of CVD synthesis of CNTs with other precursors.

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