The metal-organic framework MIL-100(Al) has been used as a host to synthesize Pd nanoparticles (around 2.0 nm) embedded within the pores of the MIL, showing one of the highest metal contents (10 wt %) without degradation of the porous host. Textural properties of MIL-100(Al) are strongly modified by Pd insertion, leading to significant changes in gas sorption properties. The loss of excess hydrogen storage at low temperature can be correlated with the decrease of the specific surface area and pore volume after Pd impregnation. At room temperature, the hydrogen uptake in the composite MIL-100(Al)/Pd is almost twice that of the pristine material. This can be only partially accounted by Pd hydride formation, and a "spillover" mechanism is expected to take place promoting the dissociation of molecular hydrogen at the surface of the metal nanoparticles and the diffusion of monatomic hydrogen into the porosity of the host metal-organic framework.

[20] Calculations of optical densities at 313 nm suggest that all photochromic molecules absorb light in the 4 lm SmC* films, assuming a liquid crystal density of 0.8 g cm ±3 : OD = 0.33 at 3 mol-%, 1.09 at 10 mol-% and 2.14 at 20 mol-%.[21] P. Kloess, J. McComb, H.

Hydrogen sorption properties of ultrasmall Pd nanoparticles (2.5 nm) embedded in a mesoporous carbon template have been determined and compared to those of the bulk system. Downsizing the Pd particle size introduces significant modifications of the hydrogen sorption properties. The total amount of stored hydrogen is decreased compared to bulk Pd. The hydrogenation of Pd nanoparticles induces a phase transformation from fcc to icosahedral structure, as proven by in situ XRD and EXAFS measurements. This phase transition is not encountered in bulk because the 5-fold symmetry is nontranslational. The kinetics of desorption from hydrogenated Pd nanoparticles is faster than that of bulk, as demonstrated by TDS investigations. Moreover, the presence of Pd nanoparticles embedded in CT strongly affects the desorption from physisorbed hydrogen, which occurs at higher temperature in the hybrid material compared to the pristine carbon template.

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The synthesis of mesoporous boron nitride, using an aminoborazine as the boron nitride source, with silica (SBA-15) or mesoporous carbon (CMK-3) as the template is compared. Tri(methylamino)borazine (MAB) is converted to BN inside the mesopores of silica or carbon molecular sieves through a mild thermal process. Boron nitride is obtained after the removal of the hard template using an ammonia thermal treatment (carbon template) or an HF treatment (silica template). X-Ray diffraction, TEM and pore size analysis show that the structure of the BN molecular sieves synthesized from the carbon template consisted of a 2D regular array of uniform mesopores 3.4 nm in diameter. The hydrophilic nature of the silica template prevents successful pore filling with the aminoborazine precursor. Ordered BN molecular sieves are obtained at 1000 uC with a specific surface area of 500 m 2 g 21 using mesoporous carbon molecular sieves as a hard-template.

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Highly ordered two-dimensional (2D) mesoporous silicoboron carbonitride (SiBCN) materials were prepared by a double nanocasting approach using mesoporous SBA-15 silica as starting template. The latter was converted into its negative replica CMK-3 carbon template, which was subsequently impregnated with a boron-modified polysilazanes of the type [B(C2H4SiCH3NCH3)3] n ([C14.4H31.4N4.1B1.0Si3.0] n ) using a liquid-phase impregnation (LPI) process. The derived [B(C2H4SiCH3NCH3)3] n -carbon composite was cross-linked under ammonia at 200 °C and then thermolyzed under nitrogen at 1000 °C to generate a SiBCN-carbon composite. The carbon template was subsequently removed through thermal treatment at 1000 °C in an ammonia atmosphere to generate ordered mesoporous structures. XRD and TEM analyses revealed that as a negative replica of the CMK-3 template, the obtained amorphous mesoporous material exhibited open, continuous, and ordered 2D hexagonal frameworks, whereas elemental analyses indicated the formation of materials with an empirical formula of Si3.0B1.0C4.2N3.5. The ordered mesoporous Si3.0B1.0C4.2N3.5 material displayed high surface area (600 m2 g−1), high pore volume (0.61 cm3 g−1), and narrow pore size distribution (around 3.4 nm) and exhibited a relatively good thermal stability in air through heat-treatment to 1400 °C.

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