Determination of the adsorption energy distribution function of UPD hydrogen on monocrystalline platinum

Hydrogen underpotential deposition (upd) on basal planes of platinum is a complex process. Hydrogen isotherms determined from cyclic voltammetric experiments were modeled using distribution functions. This problem leads to the Fredholm integral equation of the first kind. Hydrogen upd in HClO4 was modeled assuming a local Langmuir isotherm and the distribution function of the adsorption energies was determined. In H2SO4 the isotherms are much narrower so the local Frumkin isotherm was used and the distribution of the interaction parameter was determined. The distribution functions obtained were used to reconstruct the isotherms and a good agreement was obtained between recalculated and experimental isotherms. The proposed method gives good insight into the interactions of H-Pt.