PERIODIC VARIATION OF EXCHANGE CURRENT DENSITY OF HYDROGEN ELECTRODE REACTION WITH ATOMIC NUMBER

The works on hydrogen electrode reaction have been increasingly accumulated during the last decade. These works are much more reliable than earlier ones, in­ asmuch as the special precaution has been taken against contaminations of solution and electrode surface. Survey of the results shows that the activity of metals for the reaction in terms of the exchange current density, io (Acm -2), varies in a wide range, namely from log io = -1.2 on Pd to -12.9 on Pb and even on the same metal, from -3.15 to -7.04 on Au (ef Table 1). Such variations in the activity may be caused by several factors such as bulk property of electrode material, surface state of the electrode and solution. The present note is concerned with the relation of the exchange current density of various metals to their position in the Periodic Table and with the decision of the determining factor of the activity.