Pt nanoparticles supported on Sb-doped SnO2 porous structures: developments and issues.

In this work, high surface area antimony doped tin oxide (Sb-SnO2) has been synthesized using a modified sol-gel synthesis method. The bulk and surface properties of the metal oxide support have been investigated as a function of the processing conditions. A change in the Sb-SnO2 processing conditions, while preserving an overall invariant bulk composition, led to substantial modification of the surface stoichiometry. Accelerated stability test protocols have shown that the surface composition represents a crucial parameter for the electrochemical stability of Sb-SnO2. Model Pt/Sb-SnO2 electrodes have been developed depositing Pt nanoparticles by magnetron sputtering on the optimized Sb-SnO2 porous surface. A significant enhancement in the corrosion stability upon 1000 potential cycles between 0.5 and 1.5 V (RHE) at 50 mV s(-1) has been observed for the Pt/Sb-SnO2 system compared to Pt/carbon.

Phosphorus-31 MAS NMR investigations of pyridine stabilized dithiomonometaphosphoryl halides.

Phosphorus-31 magic-angle spinning NMR spectroscopy was chosen in order to study a series of N-donor stabilized dithiomonometaphosphoryl halides (F, Cl, and Br) and to extract structural and bonding information from their spectra. Additionally, an unusual line splitting was observed in the 31P MAS NMR spectra of pyridine dithiomonometaphosphoryl chloride (Py-->PS2Cl) and the analogous bromide (Py-->PS2Br). It is shown that this effect is due to a residual dipolar coupling between phosphorus and chlorine or bromine, respectively. This work is to our knowledge the first observation of this effect between P and Br in 31P MAS NMR spectra.

Ferromagnetic ordering in alkali-metal iron antimonides: NaFe4Sb12 and KFe4Sb12.

New alkali-metal compounds with the filled-skutterudite structure were synthesized and their chemical and physical properties investigated. X-ray diffraction, microprobe, and chemical analysis established the structure and the composition without defects on the cation site. Magnetization, ac susceptibility, specific heat, resistivity, and NMR or NQR demonstrated NaFe4Sb12 to be ferromagnetic below approximately 85 K and to exhibit an additional magnetic anomaly around 40 K. Band structure calculations find a large density of states at the Fermi energy and a ferromagnetic ground state. Similar behavior was observed for KFe4Sb12.

Pyridinium dihydrogenmonothiophosphate.

By reaction of pyridine dithiomonometaphosphoryl fluoride with ethyldiphenylphosphine in the presence of traces of water, we isolated crystals of the title compound, (I). In the structure of this salt, two kinds of hydrogen bonds were detected. They link N-H (part of the cation), as well as one O-H group (part of the anion), to the phosphoryl O atom of the anion. The donor-acceptor distances are 2.654 (1) and 2.568 (1) A, respectively. The P-O and P-S bond lengths are 1.514 (2) and 1.967 (1) A, respectively, which fall therefore in the range of a 1.5-fold bond.