Kinetic Study of the hydrogen electrode reaction on Bi-modified Platinum

Abstract

The present work deals with a kinetic study of the hydrogen electrode reaction (HER) on a platinum electrode modified by bismuth adatoms in both cathodic and anodic range of overpotentials. Kinetic expressions previously derived for the Volmer-Heyrovsky-Tafel mechanism were modified in order to take into account the influence of bismuth. Thus, a modification of the adsorption energy of the reaction intermediate, described through the variation of the Frumkin interaction parameter, and a possible effect of inhibition on the active sites were included in the kinetic expressions. On this basis, the experimental results obtained in the overpotentials range -0.20 < h / V < 0.40 were successfully correlated through the variation of only four adjustable parameters, which dependence on the bismuth surface coverage were evaluated and discussed.