Small gold (5 nm) and zirconia (2-3 nm) particles inside the mesopores of SBA-15 were visualized with bright-field electron tomography. Due to the ordered nature of the mesopores and the related diffraction contrast present in the tilt series, the 3D-reconstruction is difficult to interpret. Unequivocal information has been obtained, however, on the presence of the particles in certain pores, while others pores are empty. This nonuniform distribution of particles over the mesopores explains the two-step desorption isotherm in nitrogen physisorption experiments.

The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field.

In our previous study (Wang, Y. Q.; Yang, C.-M.; Zibrowius, B.; Spliethoff, B.; Lindén, M.; Schüth, F. Chem. Mater. 2003, 15, 5029), mesoporous vinyl-functionalized silica (vinyl silica) with hexagonal P6mm and cubic Ia3d structures has been synthesized at different loadings of vinyl groups and at different concentrations of sodium chloride when triblock copolymer P123 was used as a template. Our further investigations presented in this article reveal that at a loading of 10% vinyl groups, well-ordered cubic Ia3d structure was obtained at a low concentration of Na2SO4 (0.5 M) and the hexagonal structure was produced at 1.0 M NaCl. When NaNO3 was used as the inorganic salt, the hexagonal structure was still maintained even at a salt concentration of 2.0 M. The result is in accordance with the Hofmeister series order (salting-out effect): SO4(2-) > Cl- > NO3(-). The lowering of the acidity also induced the formation of the cubic Ia3d structure. At 20% loading, hexagonal structure can be obtained by adding the more hydrophilic Pluronic F127 (EO106PO70EO106) to the acidic solutions of P123, but the hexagonal structure cannot be produced with pure P123 under the synthesis conditions investigated. All of these results can be rationalized through hydrophilic-hydrophobic balance and the change in micellar curvature. Furthermore, 10% mercaptopropyl-functionalized mesoporous silica with cubic Ia3d structure was designed and synthesized successfully with the assistance of an inorganic salt (NaCl) in an acidic solution of P123, which is the first example of mercaptopropyl-functionalized large-pore mesoporous silica with high loadings.