Determination of different local potentials of zero charge of a Pd¯Au(111) heterogeneous surface

Local values of potential of zero charge (pzc) and potential of zero total charge (pztc) have been determined for Au(111) surfaces partially covered with palladium at low coverages. The pztc of the palladium islands has been measured with the CO charge displacement procedure. The adsorption of CO only takes place on the palladiumcovered domains allowing us to selectively displace the charge residing in this part of the surface. The resulting pztc values of the palladium islands are located around 0.25 V for the entire range of palladium coverages. The pzc of gold-uncovered areas has been determined by identifying the position of the differential capacity minimum (0.52 V). It appears that this pzc is only slightly affected by the presence of deposited palladium.