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

研究了氢在铂界面上的动力学性质。用原始的电化学方法研究了H的化学势，并讨论了H浓度的波动。从温度依赖关系出发，对氢的释放过程等动力学过程进行了评价，并测量了同位素效应。研究结果如下：(1)氢在铂上的起伏：测量了铂氢电池电动势的起伏及其与温度的关系。这种波动可以归结为马尔科夫过程。电动势的起伏是由于铂上的氢浓度起伏引起的。从标准差对温度的依赖关系，估算了该过程的活化能。(2)H在铂上的界面反应：研究了H在铂界面上的界面反应。测量了铂氢电池的电动势和短路电流。讨论了表面电动势与功函数的关系，并用H吸附位置的关系解释了电流的关系。从表面驰豫或重构的角度讨论了电动势和电流对温度的依赖关系。(3)同位素效应：用质量法测定了氢同位素对铂的电解分离因子(S因子)。S因子得分为5.0。在过渡态方法的基础上讨论了它的值。观察了其与温度的关系，得到了其活化能。结果表明，铂上的析氢过程属于慢复合机制。结合电化学研究，讨论了欠压区的S因子。结果(1)正在准备中，(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.