Electrochemical double layers (EDL) form at electrified interfaces. Whereas the Gouy-Chapman model describes moderately charged EDL, the formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by X-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer was confirmed by glancing-incidence in-plane diffraction measurements.

Ultramicroelectrodes (UMEs) are important in electrochemistry and electroanalysis because of the special mass transfer conditions observed with respect to those at electrodes of normal dimensions. [1] This property has been used to facilitate the measurement of very fast electron transfer kinetics, a well-known example being the electrooxidation of ferrocene. [2] On the other hand UMEs made from metals in the usual way are necessarily polycrystalline in nature. As a the center of one of the two cyclopentadienyl rings (0.124 ). The C g -Ln-C g angles of the less constrained five-atom-bridged bis(indenyl)lanthanocenes [{O(CH 2 CH 2 C 9 H 6 ) 2 }LnCl(thf)] [12] (131.48 Ln Nd, 132.38 Gd, 132.68 Ho) are larger and show little dependence on the size of the central metal cation.It is expected that 1 and 2 will be useful as reducing agents due to the presence of minor quantities of uncoupled acene radical anionic species in solution, detected by ESR spectroscopy. Reactiviy studies of both complexes are in progress. Experimental SectionAll manipulations were performed under nitrogen atmosphere or in vacuum. Elemental analyses were obtained by using a Perkin-Elmer Series II CHNS/O 2400 Analyzer, NMR spectra were recorded on a Bruker ARX 200 instrument. The commercially available acenaphthylene (Aldrich; purity 75 %) was purified further to 85 % (10 to 15 % acenaphthene as impurity) by sublimation (80/10 À1 Torr). The given quantities of acenaphthylene and the yields of the products refer to pure acenaphthylene.

Strain is known to enhance the activity of the oxygen reduction reaction in catalytic platinum alloy nanoparticles, whose inactivity is the primary impediment to efficient fuel cells and metal−air batteries. Bragg coherent diffraction imaging (BCDI) was employed to reveal the strain evolution during the voltammetric cycling in Pt−Ni alloy nanoparticles composed of

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We used in situ Se K-edge X-ray spectroscopy to characterize Ru nanoparticles chemically modified with submonolayers of selenium (Se/Ru) [Cao et al. J. Electrochem. Soc. 2006, 153, A869]. X-ray powder diffraction verified that the Se/Ru catalyst had metallic Ru cores. The in situ X-ray absorption near edge structure taken at the open circuit potential showed that there were both elemental and oxidized selenium on the as-prepared Se/Ru samples. All selenium oxide was reduced to the elemental form of selenium by applying negative potentials. By applying positive potentials, selenium was subsequently reoxidized. The analysis of the extended X-ray absorption fine structure shows the appearance of selenium hydration (Se-OH 2 ) in a deaerated solution, which was not observed during the oxygen reduction reaction. We present evidence that Se-free Ru atoms play an important role in the ORR activity of the Se/Ru catalyst studied in this paper.