Periodic Variation of Exchange Current Density of Hydrogen Electrode Reaction with Atomic Number and Reaction Mechanism

A survey of recent results shows that the activity log io is a periodic function of the atomic number for each long period. It is concluded that the bulk properties of electrode dominate its activity. Also, log io decreases l inearly with heat o ~ adsorption or increases l inearly with work function for the transition metals, but remains unchanged for the metals following them (the ascending metals). These relations are qualitatively interpreted by the catalytic and the electrochemical mechanism for the transition and the ascend-ing metals, respectively. The hydrogen electrode reaction 2H + 4- 2e- = He [1] is one of the simplest and the most fundamental ly important reactions among various kinds of hetero-geneous catalyses, and its solid understanding would be a milestone in the approach toward complicated