Subnanometric metal species (single atoms and clusters) have been demonstrated to be unique compared to their nanoparticulate counterparts. However, the poor stabilization of subnanometric metal species towards sintering at high temperature (>500 o C) under oxidative or reductive reaction conditions limits their catalytic application. Zeolites can serve as an ideal support to stabilize subnanometric metal catalysts, but it is challenging to localize subnanometric metal species on specific sites and modulate their reactivity. We have achieved a very high preference for localization of highly stable subnanometric Pt and Pt-Sn clusters in the sinusoidal channels of purely siliceous MFI zeolite, as revealed by atomically resolved electron microscopy combining high-angle annular dark-field and integrated differential phase contrast imaging techniques. These catalysts show very high stability, selectivity, and activity for the industrially important dehydrogenation of propane to form propylene. This stabilization strategy could be extended to other crystalline porous materials.

Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here we show how the catalytic properties of subnanometric Pt clusters (0.5-0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite modulate upon introduction of partially reduced Sn species that interact with the noble metal at the metal/support interface. The low mobility of Sn in H2 over an extended period of time (>6 h) even at high temperatures (e.g. 600 ⁰C), which is determined by only a few additional Sn atoms added to the Pt clusters. Such structural features, which are not immediately visible by conventional characterization techniques and can be laid out after combination of in situ EXAFS, HAADF-STEM and CO-IR data, is key to provide one-order of magnitude lower deactivation rate in the propane dehydrogenation reaction while maintaining high intrinsic (initial) catalytic activity. Pt foil a12 2.763 ± 0

Polyanionic materials such as Na3V2(PO4)2F3-yOy (0 ≤ y ≤ 2) are of high interest as positive electrode for Na-ion batteries since they offer competitive electrochemical performances compared to sodiated transition metal oxides. The composition Na3V2(PO4)2F3 (y = 0) has the highest theoretical energy density among the series but surprisingly a lot of discrepancies are reported throughout the literature considering its structure and its electrochemical properties. We will show that most of the compounds reported as being Na3V III 2(PO4)2F3 are in fact slightly oxidized due to synthesis conditions resulting in a partial oxygen substitution for fluorine. In order to get an in-depth understanding of this system, a series of compositions Na3V2(PO4)2F3-yOy (0 ≤ y ≤ 0.5, i.e. near the fluorine-rich composition) was synthesized and characterized combining synchrotron X-ray diffraction, X-ray absorption spectroscopy, solid state nuclear magnetic resonance spectroscopy and galvanostatic electrochemical tests. The structural features and electrochemical signatures of these oxidized compounds will be carefully compared to those recently obtained for Na3V III 2(PO4)2F3 by Bianchini et al.

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A multiple-analyser-crystal spectrometer for non-resonant inelastic X-ray scattering spectroscopy installed at beamline ID16 of the European Synchrotron Radiation Facility is presented. Nine analyser crystals with bending radii R = 1 m measure spectra for five different momentum transfer values simultaneously. Using a two-dimensional detector, the spectra given by all analysers can be treated individually. The spectrometer is based on a Rowland circle design with fixed Bragg angles of about 88 degrees . The energy resolution can be chosen between 30-2000 meV with typical incident-photon energies of 6-13 keV. The spectrometer is optimized for studies of valence and core electron excitations resolving both energy and momentum transfer.