Adsorbate and Electrode Reactions on Pt Single Crystal Electrode -What is the Real Reaction Intermediate? -

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1. Hydrogen Electrode Reaction. The usually observed hydrogen atom on the electrode surface (Upd-H) cannot be the reaction intermediates for the hydrogen evolution reaction. The real reaction intermediate was the On-top H which is unstable.2. Nitrogen Oxide Reactions. Among a series of nitrogen oxides, No, NH_2OH and N_2H_4 are active in the electro-oxidation and/or -reduction on Au single crystal electrode. These reactions are structure-insensitive in contrast to the case on the Pt single crystal electrode. The reaction products are confirmed directly by the "One point touch" DEMS developed in our laboratory which is applicable to a small electrode of 3-5 mm in diameter.3. Oxygen Electrode Reaction. The oxygen reduction reaction appears sensitive on the surface atomic structure of the electrode but not in a direct manner ; i.e., the specific adsorption of anion is structure sensitive and affects the electrode reaction. In addition, it was found that the oxygen reduction reaction does … More not require so much reaction sites of the surface, being at most 0.03% of the total Upd-H sites.4. Oxidation of C_1 compounds. The formic acid oxidation shows the structure dependence and Pt (100) reveals the highest activity. The reaction proceeds via two routes ; one is predominant in a less positive potential region occurs with a small number of reaction sites, and the other is predominant in a more positive potential region. However, the reaction is almost completely suppressed at a highly positive potential region (>1.0V), indicating the formation of the retarding species on the surface.5. Role of Water Molecules. The above retarding phenomenon is observed on the other electrode reactions studied and must be attributed to a common factor. The present work concludes that the water molecule is now tightly bound on the surface in the highly potential region and prohibits the interaction of the reactant with the surface. This will be a key information to solve, for example, the high overpotential of the oxygen reduction on the most efficient electrocatalyst of Pt, which is used in the fuel cell. Less