Dynamical Properties of Hydrogen and Concentration Fluctuation of Hydrogen on a Metal

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Dynamical properties of H on Pt interface have been studied. By means of original electrochemical method, the chemical potential of H was investigated and the fluctuation of H concentration was discussed. From the temperature dependence, dynamical processes such as the released processes of H were evaluated and the isotope effect was also measured. Detals of research results are shown as follows.(1) Fluctuation of H on Pt : Fluctuation of the electromotive force (EMF) of a Pt-H cell and its temperature dependence were measured. The fluctuation can be grouped in a Markoff process. The origin of the EMF fluctuation is due to the H concentration fluctuation on Pt. From the temperature dependence of the standard deviation, the activation energy of the process was evaluated.(2) Interfacial reactions of H on Pt : Interfacial reactions of H on Pt interfaces have been studied. The EMF of a Pt-H cell and the current in a short circuit of the cell were measured. The surface orientation dependence of the EMF was discussed on that of the work function, and the dependence of the current was interpreted by that of H adsorption sites. The temperature dependence of the EMF and the current was discussed in terms of surface relaxation or reconstruction.(3) Isotope effect : The electrolytic separation factor (S factor) of H isotopes for Pt was measured by means of mass analysis. The value of S factor was 5.0. The value was discussed on the basis of the transition state method. Its temperature dependence was observed and the activation energy was obtained. The results were revealed that the hydrogen evolution process on Pt is assigned to a slow recombination mechanism. The S factor in the undervoltage region was discussed by taking account of electrochemical studies.The result (1) is in preparing, (2) is submitted and (3) is published.