CORRELATION BETWEEN THE PROPERTIES OF METAL ATOMS AND THE EXCHANGE CURRENT DENSITIES OF HYDROGEN ELECTRODES.

The hydrogen evolution reaction in water has long been used as a model for studying phenomena of electrocatalysis. The most convenient characteristic of the reaction rate is the exchange current density (i//o). The experimental data for i//o in acidic media were previously analyzed and the results of that work is used by the author. A discussion is presented of the two-electron mechanism of reaction. It is known that Pt and other group-VIII metals are effective catalysts, not only for the hydrogen evolution reaction but also for the oxygen evolution reaction where two-electron models are widely discussed. Therefore, the suggested ability of Pt to function as a two-electron donor (or acceptor) can explain the high activity of platinum in many electrochemical reactions. Possibly the same explanation holds for the high catalytic activity which is displayed by platinum, not only in electrochemical but also in many chemical redox reactions associated with the rupture of covalent two-electron bonds.