Hydrogen Overvoltage on Bright Platinum

The effect of hydrogen pressure on the hydrogen overvoltage of bright platinum was determined in acid. From the anodic and cathodic overvoltages, kinetic parameters were determined. A mechanism controlled by slow combination of hydrogen atoms adsorbed on the platinum surface fits the experimental data. From the Langmuir adsorption isotherm it is shown that the surface of the active platinum electrode at equilibrium is sparsely covered with hydrogen atoms.