The mechanism for hydrogen adsorption on platinum electrodes from acidic aqueous media: Part I. Potential step relaxation theory for several adsorption mechanisms

Abstract Expressions for the relaxation time constants, equilibrium pseudocapacitances, and equilibrium faradaic resistances are derived for five adsorption mechanisms: (1) Langmuir-like adsorption onto an electrode with only one type of adsorption site, (2) adsorption as in the previous mechanism but with interactions between adsorbed species, (3) independent Langmuir-like adsorption onto each of the different types of sites found on a polycrystalline electrode, (4) adsorption onto an electrode with several different types of adsorption sites, all of which are in rapid surface equilibrium, and (5) adsorption onto a polycrystalline electrode where the movement of the adsorbate between different types of sites is the rate determining step.