Structural effects in electrocatalysis: oxidation of formic acid and hydrogen adsorption on platinum single-crystal stepped surfaces

Abstract

The oxidation of formic acid and hydrogen adsorption have been measured on platinum single-crystal stepped surfaces with five orientations. A pronounced structural sensitivity of both reactions has been found. They show a sensitivity to the terrace orientation, the density of steps and to the step orientation The surfaces which are blocked for reaction by intermediates formed in the oxidation of formic acid, as the Pt(100) and Pt(110) surfaces are, become more active upon introduction of steps. The surface which are not blocked, i.e. the Pt(111) surface, become less active upon introduction of steps because more active steps increase their activity for the "wrong" reaction - the formation of blocking intermediates. Preliminary data on hydrogen adsorption show the possibility of using this reaction as a check of the degree of order and orientation of sigle-crystal Pt surfaces.