Effect of the Pt/Pt Electrode Roughness on the Interaction of CO with Oads

Transients of potential E during the CO-O_ads interaction on Pt/Pt electrodes of different roughness (f = 20-1200), measured in 0.5 M H₂SO₄ under open-circuit conditions, slow down with increasing f. Dependence of specific activity of Pt/Pt on f cannot be described by one CO-O_ads interaction mechanism in a wide range of f. At f < 100, more acceptable is the mechanism suggested earlier for polycrystalline (smooth) Pt, and at larger f—mechanism of conjugated reactions. Presumably, increasing f at small f reduces intrinsic electrocatalytic activity of the Pt surface, while at large f inner-diffusion limitations can arise.