Positive shift of the potential of zero total charge of stepped Pt(1 1 1) electrodes decorated by irreversibly adsorbed bismuth

The value of the potential of zero total charge (pztc) of stepped Pt(1 1 1) electrodes, whose step sites have been blocked by irreversibly adsorbed bismuth, has been determined by means of the CO displacement experiment. It has been observed that the pztc of the decorated surfaces shift positively with respect to that of the substrate stepped surface electrode. In this way the electrode total charge at constant potential diminishes by effect of the adatom adsorption. The oxidation of adsorbed CO takes place at higher potentials on the decorated surfaces, pointing out a direct effect of the pztc shift on their reactivity as electrocatalyzers.