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

研究了H在Pt界面上的动力学性质。采用原始的电化学方法，研究了氢的化学势，讨论了氢浓度的波动。从温度依赖性出发，评价了氢的释放过程等动力学过程，并测量了同位素效应。研究结果详情如下：(1) H在Pt上的波动：测量了Pt-H电池电动势（EMF）的波动及其温度依赖性。波动可以归为马尔科夫过程。电动势波动的来源是Pt上H浓度的波动。根据标准偏差对温度的依赖，评估了该过程的活化能。(2) H与Pt的界面反应：研究了H与Pt界面的界面反应。测量了Pt-H电池的电动势和短路时的电流。讨论了电动势的表面取向与功函数的关系，并用H吸附位的关系解释了电流的关系。从表面松弛或重构的角度讨论了电动势和电流的温度依赖性。(3)同位素效应：用质谱法测定了Pt的H同位素的电解分离因子（S因子）。S因子值为5.0。在过渡状态法的基础上讨论了该值。观察了其温度依赖性，得到了活化能。结果表明，铂表面的析氢过程属于缓慢的复合机制。结合电化学研究，讨论了欠压区S因子的影响。结果(1)在准备中，(2)已提交，(3)已发表。

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.