The dual path mechanism for methanol decomposition on well-defined low Miller index platinum single crystal planes, Pt(111), Pt(110), and Pt(100), was studied using a combination of chronoamperometry, fast scan cyclic voltammetry, and theoretical methods. The main focus was on the electrode potential range when the adsorbed intermediate, CO(ad), is stable. At such "CO stability" potentials, the decomposition proceeds through a pure dehydrogenation reaction, and the dual path mechanism is then independent of the electrode-substrate surface structure. However, the threshold potential where the decomposition of methanol proceeds via parallel pathways, forming other than CO(ad) products, depends on the surface structure. This is rationalized theoretically. To gain insights into the controlling surface chemistry, density functional theory calculations for the energy of dehydrogenation were used to approximate the potential-dependent methanol dehydrogenation pathways over aqueous-solvated platinum interfaces.

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We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li(+) storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage.

Oxygen reduction reaction ͑ORR͒ was carried out in a sulfuric acid solution saturated with oxygen on Ru and Rh nanoparticles chemically modified with Se or S. Among the four chalcogen-modified specimens examined, the modification of Ru with Se shows the highest activity. ͓P. Zelenay et al., U.S. Pat. Appl. filed Dec. 5, 2005͔. Therefore, the highlight of this study is the synthesis and use of the Ru/Se catalyst vs the cluster-type Ru x Se y catalysts investigated before, and on providing evidence toward similar reactivity functions between Ru/Se and Ru x Se y . On the nanoparticle Ru/Se electrode, ORR commences at 0.9 V and the diffusionlimiting reduction current is attained at ϳ0.4 V ͑vs a reference hydrogen electrode͒. ORR activity does not decrease in the presence of methanol, showing a full methanol tolerance at methanol concentrations investigated in this study. It is proposed that surface metallic Ru atoms embedded in Se matrices are the catalytic active sites to sustain ORR at a high level. However, the smooth Ru disk surface modified by selenium displays lower activity than a "clean" Ru disk ͑without Se͒ and a noticeably lower activity than the nanoparticle Ru/Se. Possible reasons for this behavior are discussed. Finally, a Ru/S catalyst is slightly more active than a H 2 -reduced Ru black catalyst but is much less active than Ru/Se and Ru x Se y , and is also methanol-tolerant at 0.1 M methanol concentrations. Both Se and S reduce ORR rates on Rh.

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