Surface stress observations during the adsorption and electrochemical oxidation of CO on Pt{111}

The adsorbate-induced surface stress was studied for the system CO/Pt{111}-textured thin films in CO-saturated 0.1 M HClO₄ and characterized through the techniques of cyclic voltammetry and chronoamperometry. A compressive stress of -1.1 N/m was measured for a saturation coverage. It is shown that CO blocks the electrode both electrochemically (charge transfer) and physically (surface stress changes). Additionally, it is demonstrated with surface stress measurements that CO does not desorb with the removal of CO from the electrolyte. The adsorption kinetics of CO are shown to be slow, with a saturation coverage taking more than 65 s to acquire. When driven electrochemically, CO oxidation kinetics are fast, occurring in much less than 1 s.